Loan Amortisation Calculator

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Results

Monthly payment is 477.42 $ / months. Total interest paid is 71869.51 $. Total repaid is 171869.51 $.

Monthly payment: $ / months
Total interest paid: $
Total repaid: $

Repayment schedule

Repayment schedule
Month	Payment (USD)	Interest (USD)	Principal (USD)	Balance remaining (USD)
1	477.42	333.33	144.08	99855.92
2	477.42	332.85	144.56	99711.36
3	477.42	332.37	145.04	99566.31
4	477.42	331.89	145.53	99420.78
5	477.42	331.40	146.01	99274.77
6	477.42	330.92	146.50	99128.27
7	477.42	330.43	146.99	98981.28
8	477.42	329.94	147.48	98833.81
9	477.42	329.45	147.97	98685.84
10	477.42	328.95	148.46	98537.37
11	477.42	328.46	148.96	98388.42
12	477.42	327.96	149.45	98238.96
13	477.42	327.46	149.95	98089.01
14	477.42	326.96	150.45	97938.56
15	477.42	326.46	150.95	97787.61
16	477.42	325.96	151.46	97636.15
17	477.42	325.45	151.96	97484.19
18	477.42	324.95	152.47	97331.72
19	477.42	324.44	152.98	97178.74
20	477.42	323.93	153.49	97025.26
21	477.42	323.42	154.00	96871.26
22	477.42	322.90	154.51	96716.75
23	477.42	322.39	155.03	96561.72
24	477.42	321.87	155.54	96406.18
25	477.42	321.35	156.06	96250.12
26	477.42	320.83	156.58	96093.54
27	477.42	320.31	157.10	95936.43
28	477.42	319.79	157.63	95778.81
29	477.42	319.26	158.15	95620.65
30	477.42	318.74	158.68	95461.97
31	477.42	318.21	159.21	95302.77
32	477.42	317.68	159.74	95143.03
33	477.42	317.14	160.27	94982.75
34	477.42	316.61	160.81	94821.95
35	477.42	316.07	161.34	94660.61
36	477.42	315.54	161.88	94498.73
37	477.42	315.00	162.42	94336.31
38	477.42	314.45	162.96	94173.35
39	477.42	313.91	163.50	94009.84
40	477.42	313.37	164.05	93845.79
41	477.42	312.82	164.60	93681.20
42	477.42	312.27	165.14	93516.05
43	477.42	311.72	165.70	93350.36
44	477.42	311.17	166.25	93184.11
45	477.42	310.61	166.80	93017.31
46	477.42	310.06	167.36	92849.95
47	477.42	309.50	167.92	92682.03
48	477.42	308.94	168.48	92513.56
49	477.42	308.38	169.04	92344.52
50	477.42	307.82	169.60	92174.92
51	477.42	307.25	170.17	92004.76
52	477.42	306.68	170.73	91834.02
53	477.42	306.11	171.30	91662.72
54	477.42	305.54	171.87	91490.85
55	477.42	304.97	172.45	91318.40
56	477.42	304.39	173.02	91145.38
57	477.42	303.82	173.60	90971.78
58	477.42	303.24	174.18	90797.61
59	477.42	302.66	174.76	90622.85
60	477.42	302.08	175.34	90447.51
61	477.42	301.49	175.92	90271.59
62	477.42	300.91	176.51	90095.08
63	477.42	300.32	177.10	89917.98
64	477.42	299.73	177.69	89740.29
65	477.42	299.13	178.28	89562.01
66	477.42	298.54	178.88	89383.14
67	477.42	297.94	179.47	89203.66
68	477.42	297.35	180.07	89023.60
69	477.42	296.75	180.67	88842.93
70	477.42	296.14	181.27	88661.65
71	477.42	295.54	181.88	88479.78
72	477.42	294.93	182.48	88297.29
73	477.42	294.32	183.09	88114.20
74	477.42	293.71	183.70	87930.50
75	477.42	293.10	184.31	87746.19
76	477.42	292.49	184.93	87561.26
77	477.42	291.87	185.54	87375.72
78	477.42	291.25	186.16	87189.55
79	477.42	290.63	186.78	87002.77
80	477.42	290.01	187.41	86815.36
81	477.42	289.38	188.03	86627.33
82	477.42	288.76	188.66	86438.67
83	477.42	288.13	189.29	86249.39
84	477.42	287.50	189.92	86059.47
85	477.42	286.86	190.55	85868.92
86	477.42	286.23	191.19	85677.73
87	477.42	285.59	191.82	85485.91
88	477.42	284.95	192.46	85293.45
89	477.42	284.31	193.10	85100.35
90	477.42	283.67	193.75	84906.60
91	477.42	283.02	194.39	84712.21
92	477.42	282.37	195.04	84517.16
93	477.42	281.72	195.69	84321.47
94	477.42	281.07	196.34	84125.13
95	477.42	280.42	197.00	83928.13
96	477.42	279.76	197.65	83730.48
97	477.42	279.10	198.31	83532.16
98	477.42	278.44	198.97	83333.19
99	477.42	277.78	199.64	83133.55
100	477.42	277.11	200.30	82933.25
101	477.42	276.44	200.97	82732.27
102	477.42	275.77	201.64	82530.63
103	477.42	275.10	202.31	82328.32
104	477.42	274.43	202.99	82125.33
105	477.42	273.75	203.66	81921.67
106	477.42	273.07	204.34	81717.33
107	477.42	272.39	205.02	81512.30
108	477.42	271.71	205.71	81306.59
109	477.42	271.02	206.39	81100.20
110	477.42	270.33	207.08	80893.12
111	477.42	269.64	207.77	80685.35
112	477.42	268.95	208.46	80476.88
113	477.42	268.26	209.16	80267.72
114	477.42	267.56	209.86	80057.87
115	477.42	266.86	210.56	79847.31
116	477.42	266.16	211.26	79636.05
117	477.42	265.45	211.96	79424.09
118	477.42	264.75	212.67	79211.42
119	477.42	264.04	213.38	78998.05
120	477.42	263.33	214.09	78783.96
121	477.42	262.61	214.80	78569.16
122	477.42	261.90	215.52	78353.64
123	477.42	261.18	216.24	78137.40
124	477.42	260.46	216.96	77920.45
125	477.42	259.73	217.68	77702.76
126	477.42	259.01	218.41	77484.36
127	477.42	258.28	219.13	77265.22
128	477.42	257.55	219.86	77045.36
129	477.42	256.82	220.60	76824.76
130	477.42	256.08	221.33	76603.43
131	477.42	255.34	222.07	76381.36
132	477.42	254.60	222.81	76158.55
133	477.42	253.86	223.55	75935.00
134	477.42	253.12	224.30	75710.70
135	477.42	252.37	225.05	75485.65
136	477.42	251.62	225.80	75259.85
137	477.42	250.87	226.55	75033.30
138	477.42	250.11	227.30	74806.00
139	477.42	249.35	228.06	74577.94
140	477.42	248.59	228.82	74349.12
141	477.42	247.83	229.58	74119.53
142	477.42	247.07	230.35	73889.18
143	477.42	246.30	231.12	73658.06
144	477.42	245.53	231.89	73426.17
145	477.42	244.75	232.66	73193.51
146	477.42	243.98	233.44	72960.08
147	477.42	243.20	234.22	72725.86
148	477.42	242.42	235.00	72490.87
149	477.42	241.64	235.78	72255.09
150	477.42	240.85	236.57	72018.52
151	477.42	240.06	237.35	71781.17
152	477.42	239.27	238.14	71543.02
153	477.42	238.48	238.94	71304.08
154	477.42	237.68	239.74	71064.35
155	477.42	236.88	240.53	70823.82
156	477.42	236.08	241.34	70582.48
157	477.42	235.27	242.14	70340.34
158	477.42	234.47	242.95	70097.39
159	477.42	233.66	243.76	69853.63
160	477.42	232.85	244.57	69609.06
161	477.42	232.03	245.39	69363.68
162	477.42	231.21	246.20	69117.48
163	477.42	230.39	247.02	68870.45
164	477.42	229.57	247.85	68622.61
165	477.42	228.74	248.67	68373.93
166	477.42	227.91	249.50	68124.43
167	477.42	227.08	250.33	67874.10
168	477.42	226.25	251.17	67622.93
169	477.42	225.41	252.01	67370.92
170	477.42	224.57	252.85	67118.08
171	477.42	223.73	253.69	66864.39
172	477.42	222.88	254.53	66609.85
173	477.42	222.03	255.38	66354.47
174	477.42	221.18	256.23	66098.24
175	477.42	220.33	257.09	65841.15
176	477.42	219.47	257.94	65583.21
177	477.42	218.61	258.80	65324.40
178	477.42	217.75	259.67	65064.73
179	477.42	216.88	260.53	64804.20
180	477.42	216.01	261.40	64542.80
181	477.42	215.14	262.27	64280.53
182	477.42	214.27	263.15	64017.38
183	477.42	213.39	264.02	63753.36
184	477.42	212.51	264.90	63488.45
185	477.42	211.63	265.79	63222.66
186	477.42	210.74	266.67	62955.99
187	477.42	209.85	267.56	62688.43
188	477.42	208.96	268.45	62419.98
189	477.42	208.07	269.35	62150.63
190	477.42	207.17	270.25	61880.38
191	477.42	206.27	271.15	61609.23
192	477.42	205.36	272.05	61337.18
193	477.42	204.46	272.96	61064.22
194	477.42	203.55	273.87	60790.36
195	477.42	202.63	274.78	60515.58
196	477.42	201.72	275.70	60239.88
197	477.42	200.80	276.62	59963.26
198	477.42	199.88	277.54	59685.73
199	477.42	198.95	278.46	59407.26
200	477.42	198.02	279.39	59127.87
201	477.42	197.09	280.32	58847.55
202	477.42	196.16	281.26	58566.29
203	477.42	195.22	282.19	58284.10
204	477.42	194.28	283.13	58000.96
205	477.42	193.34	284.08	57716.88
206	477.42	192.39	285.03	57431.86
207	477.42	191.44	285.98	57145.88
208	477.42	190.49	286.93	56858.95
209	477.42	189.53	287.89	56571.07
210	477.42	188.57	288.85	56282.22
211	477.42	187.61	289.81	55992.42
212	477.42	186.64	290.77	55701.64
213	477.42	185.67	291.74	55409.90
214	477.42	184.70	292.72	55117.18
215	477.42	183.72	293.69	54823.49
216	477.42	182.74	294.67	54528.82
217	477.42	181.76	295.65	54233.17
218	477.42	180.78	296.64	53936.53
219	477.42	179.79	297.63	53638.90
220	477.42	178.80	298.62	53340.28
221	477.42	177.80	299.61	53040.67
222	477.42	176.80	300.61	52740.06
223	477.42	175.80	301.62	52438.44
224	477.42	174.79	302.62	52135.82
225	477.42	173.79	303.63	51832.19
226	477.42	172.77	304.64	51527.55
227	477.42	171.76	305.66	51221.89
228	477.42	170.74	306.68	50915.22
229	477.42	169.72	307.70	50607.52
230	477.42	168.69	308.72	50298.80
231	477.42	167.66	309.75	49989.04
232	477.42	166.63	310.79	49678.26
233	477.42	165.59	311.82	49366.44
234	477.42	164.55	312.86	49053.58
235	477.42	163.51	313.90	48739.67
236	477.42	162.47	314.95	48424.72
237	477.42	161.42	316.00	48108.72
238	477.42	160.36	317.05	47791.67
239	477.42	159.31	318.11	47473.56
240	477.42	158.25	319.17	47154.39
241	477.42	157.18	320.23	46834.16
242	477.42	156.11	321.30	46512.86
243	477.42	155.04	322.37	46190.48
244	477.42	153.97	323.45	45867.04
245	477.42	152.89	324.53	45542.51
246	477.42	151.81	325.61	45216.91
247	477.42	150.72	326.69	44890.21
248	477.42	149.63	327.78	44562.43
249	477.42	148.54	328.87	44233.56
250	477.42	147.45	329.97	43903.59
251	477.42	146.35	331.07	43572.52
252	477.42	145.24	332.17	43240.34
253	477.42	144.13	333.28	42907.06
254	477.42	143.02	334.39	42572.67
255	477.42	141.91	335.51	42237.17
256	477.42	140.79	336.62	41900.54
257	477.42	139.67	337.75	41562.79
258	477.42	138.54	338.87	41223.92
259	477.42	137.41	340.00	40883.92
260	477.42	136.28	341.14	40542.78
261	477.42	135.14	342.27	40200.51
262	477.42	134.00	343.41	39857.10
263	477.42	132.86	344.56	39512.54
264	477.42	131.71	345.71	39166.83
265	477.42	130.56	346.86	38819.97
266	477.42	129.40	348.02	38471.96
267	477.42	128.24	349.18	38122.78
268	477.42	127.08	350.34	37772.44
269	477.42	125.91	351.51	37420.94
270	477.42	124.74	352.68	37068.26
271	477.42	123.56	353.85	36714.40
272	477.42	122.38	355.03	36359.37
273	477.42	121.20	356.22	36003.15
274	477.42	120.01	357.40	35645.75
275	477.42	118.82	358.60	35287.15
276	477.42	117.62	359.79	34927.36
277	477.42	116.42	360.99	34566.37
278	477.42	115.22	362.19	34204.17
279	477.42	114.01	363.40	33840.77
280	477.42	112.80	364.61	33476.16
281	477.42	111.59	365.83	33110.33
282	477.42	110.37	367.05	32743.28
283	477.42	109.14	368.27	32375.01
284	477.42	107.92	369.50	32005.51
285	477.42	106.69	370.73	31634.78
286	477.42	105.45	371.97	31262.82
287	477.42	104.21	373.21	30889.61
288	477.42	102.97	374.45	30515.16
289	477.42	101.72	375.70	30139.46
290	477.42	100.46	376.95	29762.51
291	477.42	99.21	378.21	29384.31
292	477.42	97.95	379.47	29004.84
293	477.42	96.68	380.73	28624.11
294	477.42	95.41	382.00	28242.10
295	477.42	94.14	383.27	27858.83
296	477.42	92.86	384.55	27474.28
297	477.42	91.58	385.83	27088.44
298	477.42	90.29	387.12	26701.32
299	477.42	89.00	388.41	26312.91
300	477.42	87.71	389.71	25923.21
301	477.42	86.41	391.00	25532.20
302	477.42	85.11	392.31	25139.89
303	477.42	83.80	393.62	24746.28
304	477.42	82.49	394.93	24351.35
305	477.42	81.17	396.24	23955.11
306	477.42	79.85	397.56	23557.54
307	477.42	78.53	398.89	23158.65
308	477.42	77.20	400.22	22758.43
309	477.42	75.86	401.55	22356.88
310	477.42	74.52	402.89	21953.98
311	477.42	73.18	404.24	21549.75
312	477.42	71.83	405.58	21144.17
313	477.42	70.48	406.93	20737.23
314	477.42	69.12	408.29	20328.94
315	477.42	67.76	409.65	19919.29
316	477.42	66.40	411.02	19508.27
317	477.42	65.03	412.39	19095.88
318	477.42	63.65	413.76	18682.12
319	477.42	62.27	415.14	18266.98
320	477.42	60.89	416.53	17850.45
321	477.42	59.50	417.91	17432.54
322	477.42	58.11	419.31	17013.23
323	477.42	56.71	420.70	16592.53
324	477.42	55.31	422.11	16170.42
325	477.42	53.90	423.51	15746.91
326	477.42	52.49	424.93	15321.98
327	477.42	51.07	426.34	14895.64
328	477.42	49.65	427.76	14467.88
329	477.42	48.23	429.19	14038.69
330	477.42	46.80	430.62	13608.07
331	477.42	45.36	432.06	13176.01
332	477.42	43.92	433.50	12742.52
333	477.42	42.48	434.94	12307.58
334	477.42	41.03	436.39	11871.19
335	477.42	39.57	437.84	11433.34
336	477.42	38.11	439.30	10994.04
337	477.42	36.65	440.77	10553.27
338	477.42	35.18	442.24	10111.03
339	477.42	33.70	443.71	9667.32
340	477.42	32.22	445.19	9222.13
341	477.42	30.74	446.67	8775.46
342	477.42	29.25	448.16	8327.29
343	477.42	27.76	449.66	7877.63
344	477.42	26.26	451.16	7426.48
345	477.42	24.75	452.66	6973.82
346	477.42	23.25	454.17	6519.65
347	477.42	21.73	455.68	6063.96
348	477.42	20.21	457.20	5606.76
349	477.42	18.69	458.73	5148.04
350	477.42	17.16	460.26	4687.78
351	477.42	15.63	461.79	4225.99
352	477.42	14.09	463.33	3762.66
353	477.42	12.54	464.87	3297.79
354	477.42	10.99	466.42	2831.37
355	477.42	9.44	467.98	2363.39
356	477.42	7.88	469.54	1893.85
357	477.42	6.31	471.10	1422.75
358	477.42	4.74	472.67	950.08
359	477.42	3.17	474.25	475.83
360	477.42	1.59	475.83	0.00

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Solved for	Loan amount	Annual interest rate (APR)	Loan term	Monthly payment	Total interest paid	Total repaid

How to use this calculator

Enter Loan amount
Enter the amount you plan to borrow, in dollars; this is the starting balance the schedule counts down from as you make payments.
Enter Annual interest rate (APR)
Enter the yearly rate as a percent, for example 4 for a 4 percent APR, not as a decimal; the calculator converts it to a monthly rate to work out your payment.
Enter Loan term
Enter the loan's length in months rather than years; for example, a 30-year loan is entered as 360 months.
Read Total repaid

Total repaid ($) vs Loan amount ($)

Total repaid ($) Loan amount ($)

Interest and Principal by Month

Interest ($) Principal ($) Month

What this calculates

Amortization means paying off a loan through regular payments, so the amount you owe decreases with each payment. This page works out your monthly payment, total interest, and total repaid from the amount, rate, and term you enter. ⁵

The calculation assumes your first payment is not due on day one, but one full period into the loan. From there, the same fixed payment repeats every month until the term ends. ¹

What Amortization Means in Practice

Near the end of a loan, you owe far less interest, so most of each payment goes toward principal. This late shift, from paying mostly interest to paying mostly principal, is known as amortization. ⁴

Why Your Early Payments Are Interest-Heavy

At the start of your loan, you owe more interest, because your loan balance is still high. Most of your monthly payment is applied to the interest you owe, and only the remainder goes toward the principal. ⁴

The Formula Behind Your Monthly Payment

The standard formula multiplies the principal by the periodic interest rate. It then divides that result by one minus one plus the rate, raised to the negative number of payments. The result is the fixed payment your loan uses every month. ¹

Converting Your APR to a Monthly Rate

An interest rate is commonly referred to as an annual percentage rate, or APR, but the payment formula needs a monthly rate. When a rate is stated as APR, dividing it by twelve is an appropriate way to get the monthly rate. ¹

A Worked Example

Fixed-rate loan — 30 years: Monthly payment 477.42 $ / months

See inputs and calculation

Starting values

Loan amount: 100000 $
Annual interest rate (APR): 4 %
Loan term: 360 months

Monthly payment: 477.42 $ / months
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360))
Full branch logic
4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) : 100000 / 360
Total interest paid: 71869.51 $
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 - 100000
Full branch logic
(4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 : 100000 / 360 * 360) - 100000
Total repaid: 171869.51 $
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360
Full branch logic
4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 : 100000 / 360 * 360

Original example and source context

Consider a $100,000 loan taken out for 30 years, with monthly payments and an interest rate of 4 percent. The monthly principal and interest payment on that loan comes to $477, and that same $477 payment repeats for all 360 months of the term. ³ ¹

Reading an Amortization Schedule

An amortization schedule is a table listing payment, interest, and balance figures across the loan's duration, in order. Reading down that table shows how much of each payment reduces the balance, month by month. ¹

The Short Answer to What 'Amortized' Means

An amortized loan is one you pay off with regular payments over time, and every payment lowers what you owe. Most home loans work this way. Some don't fully amortize, though — you can make every scheduled payment and still owe money when you're done ⁵.

What's Outside This Page

You may also be looking for today's rates, San Francisco-specific rate tables, down payment or pre-approval programs. Here's what the numbers on this page actually rest on: three inputs — a principal, an annual interest rate, and a total number of payments — produce three outputs: the monthly payment, the total interest paid, and the total repaid. That's all they say ¹.

What You Need to Run the Numbers

What they do tell you is what the annuity formula needs from you before it can produce an answer: a principal amount, net of any down payment, a periodic interest rate, and a total number of payments ¹. If your rate is quoted as an APR rather than an annual interest rate, dividing it by 12 gives you the right monthly rate; if it's stated as an annual interest rate, or annual percentage yield, dividing by 12 isn't enough ¹. For a typical 30-year loan paid monthly, the number of payments is 30 times 12, or 360 ¹.

Key facts

At a 0 percent rate, payment is simply loan amount divided by term: a $1,000 loan over 60 months costs $16.67 a month with $0 interest. ¹
This calculator reads the rate you type as a percent, the recognized symbol for the number 0.01, so typing 4 sets a rate of 4 percent. ² ²
Each month, your remaining balance is multiplied by a growth factor equal to one plus the periodic interest rate, before that month's payment is subtracted. ¹
The formula tracks your balance one payment at a time: each month's balance equals last month's balance times that growth factor, minus your fixed payment. ¹

How this is calculated

Calculate a fixed monthly payment from the amount borrowed, the rate and the number of months. With no interest, divide the amount evenly across the months.

Monthly payment

If R > 0: M
Otherwise: P ÷ N

M = Fixed-payment formula
R = Monthly interest rate
P = Principal ($)
N = Number of payments (months)
loan_amount = Loan amount ($)
annual_interest_rate = Annual interest rate (APR) (%)
loan_term_months = Loan term (months)
monthly_payment = Monthly payment ($ / months)
total_interest = Total interest paid ($)
total_repaid = Total repaid ($)

Understand each part

These names are shorthand for the exact calculations below, not different formulas.

Fixed-payment formula (M)
The standard amortisation calculation for a positive fixed rate and payments at the end of each month.
See the definition of M
P * annual_interest_rate * 0.01 / 12 / (1 - (1 + R) ^ (0 - N))
Monthly interest rate (R)
Convert the annual percentage rate to a decimal monthly rate.
See the definition of R
annual_interest_rate * 0.01 / 12
Principal (P)
The amount borrowed, before interest.
See the definition of P
loan_amount
Number of payments (N)
The loan term measured in months.
See the definition of N
loan_term_months

Follow the calculation with your values

Monthly payment: 477.42 $ / months
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360))
Full branch logic
4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) : 100000 / 360
Total interest paid: 71869.51 $
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 - 100000
Full branch logic
(4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 : 100000 / 360 * 360) - 100000
Total repaid: 171869.51 $
Show arithmetic
100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360
Full branch logic
4 * 0.01 / 12 > 0 ? 100000 * 4 * 0.01 / 12 / (1 - (1 + 4 * 0.01 / 12) ^ (0 - 360)) * 360 : 100000 / 360 * 360

Full formulas, symbols and sources

monthly_payment = annual_interest_rate * 0.01 / 12 > 0 ? loan_amount * annual_interest_rate * 0.01 / 12 / (1 - (1 + annual_interest_rate * 0.01 / 12) ^ (0 - loan_term_months)) : loan_amount / loan_term_months

Total interest paid

total_interest = (annual_interest_rate * 0.01 / 12 > 0 ? loan_amount * annual_interest_rate * 0.01 / 12 / (1 - (1 + annual_interest_rate * 0.01 / 12) ^ (0 - loan_term_months)) * loan_term_months : loan_amount / loan_term_months * loan_term_months) - loan_amount

Total repaid

total_repaid = annual_interest_rate * 0.01 / 12 > 0 ? loan_amount * annual_interest_rate * 0.01 / 12 / (1 - (1 + annual_interest_rate * 0.01 / 12) ^ (0 - loan_term_months)) * loan_term_months : loan_amount / loan_term_months * loan_term_months

loan_amount: Loan amount ($)
annual_interest_rate: Annual interest rate (APR) (%)
loan_term_months: Loan term (months)
monthly_payment: Monthly payment ($ / months)
total_interest: Total interest paid ($)
total_repaid: Total repaid ($)

Frequently asked questions

What is an amortized loan?

Most home loans amortize, meaning every scheduled payment brings the balance closer to zero. Some mortgage loans do not fully amortize, so you can still owe money after every payment on the schedule. ⁵

How does mortgage amortization work?

As you pay down a mortgage, you owe less interest each month because your balance keeps getting lower. That means more of each monthly payment goes toward principal as the loan matures. ⁴

How much of my payment goes to interest and how much to principal?

The combined principal-and-interest payment does not change over the life of a fixed loan. What changes is the split: the amounts going toward principal and toward interest shift from payment to payment. ⁴

What factors affect mortgage amortization?

The payment formula runs on three inputs: the principal owed, the periodic rate, and the total number of payments. Changing any one of these changes the payment the formula produces. ¹

What happens if I make extra payments?

A payment only reduces what you owe once it is larger than the interest that accrued that period. A payment above that minimum makes progress paying off the loan, so a larger payment cuts the balance faster. ¹

Is a shorter loan term better than a 30-year loan?

These sources work through a 30-year loan, equal to 360 monthly payments, and a five-year balloon loan example ³. Enter different values in the term field to see how your own payment and total interest change. ¹

What other borrowing expenses should I expect?

The sourced material behind this calculator addresses a loan's own principal and interest payment. This page's own outputs are limited to the monthly payment, total interest, and total repaid computed from what you enter. ³

What is a balloon payment?

With a five-year balloon loan, you make a set payment for five years, then owe the remaining balance in one lump sum. In the sourced example, that remaining balance comes to $90,448, due at the end of the fifth year. ³

Limitations & common mistakes

This page accepts loan amounts from 1,000 to 2,000,000 dollars; both edges are this page's own limit, not a boundary the payment formula itself requires.
It accepts annual interest rates from 0 to 36 percent; the 36 percent ceiling is this page's own limit, while the formula itself is valid when the rate is greater than zero, with a separate formula for a zero rate.
It accepts loan terms from 1 to 480 months; both edges are this page's own limit, and it refuses to calculate and states the limit for any input outside these three ranges.
The monthly payment, total interest, and total repaid shown here are computed only from the loan amount, rate, and term you enter; they are only as exact as those numbers and are not a substitute for a measurement taken on site or for a professional's judgment where one is required.
The formula assumes one fixed interest rate and one fixed payment amount for the entire term; it does not model a variable rate or extra payments that change the schedule.

By Editorial Team, Assembled from the cited primary sources; not yet expert-reviewed

Last updated September 10, 2026

Sources current as of September 10, 2026

How we review

Formula, sources, and review

This calculation follows the formula published on this page and rests on 5 cited sources, listed under Sources below. Checked by the Editorial Team on September 10, 2026. No reviewer with a finance credential has signed this page.