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Calculators you can cite.
Every result is computed the same way every time, and every constant is traced to its published authority — reference-grade math you can put in a report and defend.
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Construction & Materials
Volumes, quantities, and material estimates you can cite.
1 calculator
Home & Climate
Sizing and efficiency for comfortable, efficient homes.
1 calculator
Statistics
Rigorous, source-cited statistical calculators.
1 calculator
Other
More calculators.
10 calculators
Featured calculators
Home & Climate
Room Air Conditioner Size Calculator
Calculate the BTU cooling capacity a room air conditioner needs based on square footage, sunlight, occupants, and kitchen use, per ENERGY STAR guidance.
Other
BMR Calculator
Estimate BMR and TDEE with Mifflin-St Jeor, Schofield, or Henry (UK SACN) equations, and see whether your age fits the equation you picked.
Construction & Materials
Concrete Calculator
Estimate concrete volume, bags, and weight for slabs, footings, and round columns using Quikrete bag yields and NIST unit conversions.
Every calculator
Every calculator we publish, grouped by field. Each one is deterministic and cites its sources.
Construction & Materials
1Volumes, quantities, and material estimates you can cite.
Concrete Calculator
Estimate concrete volume, bags, and weight for slabs, footings, and round columns using Quikrete bag yields and NIST unit conversions.
Home & Climate
1Sizing and efficiency for comfortable, efficient homes.
Room Air Conditioner Size Calculator
Calculate the BTU cooling capacity a room air conditioner needs based on square footage, sunlight, occupants, and kitchen use, per ENERGY STAR guidance.
Statistics
1Rigorous, source-cited statistical calculators.
Confidence Interval for a Proportion Calculator
Calculate an exact binomial confidence interval for a proportion from observed events, sample size, and confidence level.
Other
10More calculators.
BMR Calculator
Estimate BMR and TDEE with Mifflin-St Jeor, Schofield, or Henry (UK SACN) equations, and see whether your age fits the equation you picked.
Electric Car Charging Cost Calculator
Estimate what a trip or a charging session costs on electricity versus gasoline, using your own rate, efficiency, and battery size.
Heat Index Calculator
Calculate the heat index, how hot it really feels, from air temperature and relative humidity using NWS formulas.
Loan Amortisation Calculator
Enter loan amount, APR, and term to calculate your monthly payment, total interest paid, and total amount repaid.
P-Value Calculator
Turn a Z, t, chi-square, or F statistic into a p-value, see the decision at your significance level, and check if it is borderline.
Rainwater Catchment Yield Calculator
Estimate collected rainwater from catchment area, rainfall depth, and runoff coefficient with staged formulas, examples, and clear limits.
Sample Size Calculator
Work out the minimum sample size per group for comparing an average or a rate, one group against a target or two groups against each other.
Survey Sample Size Calculator
Estimate the survey responses and invitations you need for a percentage or average, based on confidence level, margin of error, and response rate.
Triangle Solver Calculator
Enter three known parts of a triangle — sides or angles, in one of four combinations (three sides, two sides and the included angle, two angles and the included side, or two angles and a non-included side) — and get every side, angle, the area, and the perimeter.
Wind Chill Calculator
Calculate wind chill from air temperature and wind speed, then read source-based guidance on cold, frostbite, and hypothermia.
Why you can cite these
Deterministic
The same inputs always give the same result — no model drift, no surprises.
Sourced
Every constant links to the standard or datasheet it came from.
Watched
Pages are monitored for source changes and rebuilt when they move.