Payback Period Calculator
How long an investment takes to repay itself.
Calculators
Everyday maths, money and measurements, worked out for you.
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Average Return Calculator
CAGR against the arithmetic mean, and why they differ.
CD Calculator
Certificate of deposit maturity value, APY and early withdrawal.
Finance Calculator
Solve for any of PV, FV, payment, rate or number of periods.
Temperature Calculator
Convert Celsius, Fahrenheit and Kelvin with the formulas shown.
Electricity Cost Calculator
What an appliance costs to run per hour, day, month and year.
Body Surface Area Calculator
BSA by the Du Bois, Mosteller, Haycock and Boyd formulas.
Pregnancy Calculator
Estimate a due date and see the week-by-week pregnancy timeline.
Calorie Calculator
Daily calories to maintain, lose or gain weight at your own pace.
Date Calculator
Add or subtract days, weeks, months and years from any date.
Break-Even Calculator
Find the units and revenue needed to cover your fixed costs.
Profit Margin Calculator
Gross margin, profit and the selling price a target margin needs.
Tip Calculator
Work out the tip and split the bill between any number of people.
GST Calculator
Add or remove GST at any rate, with the net, tax and gross shown.
Conception Calculator
When conception most likely happened, and the window around it.
Long Division Calculator
Long division worked out step by step, as you would write it.
Prime Factorization Calculator
Prime factors, exponent form and a factor tree.
Percent Error Calculator
Percent error, absolute error and relative error together.
Number Sequence Calculator
Arithmetic, geometric and Fibonacci terms and sums.
Sample Size Calculator
How many people you need to survey, and the margin of error.
Right Triangle Calculator
Solve a right triangle from any two known values.
Stair Calculator
Rise, run and stringer length that meet code.
BTU Calculator
Heating and cooling BTU needed for a room.
Percent Off Calculator
Sale price, amount saved and stacked discounts.
Margin Calculator
Solve for margin, markup, cost or revenue from any two.
Lease Calculator
Any lease: payment, implicit rate or present value.
Estate Tax Calculator
Taxable estate after the exemption, and the tax due.
Present Value Calculator
What a future amount or payment stream is worth today.
Standard Deviation Calculator
Sample and population standard deviation with every step shown.
Weight Calculator
Convert weights and work in stones, pounds and ounces.
Running Pace Calculator
Race finish times, split tables and a predictor for other distances.
Healthy Weight Calculator
Your healthy weight range from BMI, height and frame.
Simple Interest Calculator
Work out simple interest with the I = PRT formula and full working.
Matrix Calculator
Add, multiply, transpose, invert and find determinants.
Slope Calculator
Slope, line equation, angle and distance from two points.
Molecular Weight Calculator
Molar mass from a chemical formula, element by element.
Sleep Calculator
Bedtimes and wake times that land between sleep cycles.
Tire Size Calculator
Compare two tire sizes and see the speedometer error.
Engine Horsepower Calculator
Estimate engine power from quarter-mile trap speed or ET.
Time Card Calculator
Weekly timesheet with breaks, overtime and pay.
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