Smart calculators for everyday life
Mortgage, auto loan, 401(k), BMI, tip, sales tax and more — accurate, instant, and built for the U.S. market.
Featured calculators
Mortgage Calculator
Estimate your monthly mortgage payment, total interest, and total cost for any home loan amount, rate, and term.
FinanceAuto Loan Calculator
Calculate your monthly car payment, total interest, and total cost for any auto loan — new or used.
FinanceCompound Interest Calculator
See how savings, a 401(k), IRA, or brokerage account grows with compound interest and monthly contributions.
FinanceSales Tax Calculator
Calculate U.S. sales tax on any purchase — or work backwards from the total to find the pre-tax amount.
Health & FitnessBMI Calculator
Calculate your adult Body Mass Index (BMI) and its CDC weight category from your height and weight in U.S. or metric units.
MathPercentage Calculator
Quickly calculate X% of Y, what percentage one number is of another, or the percentage change between two values.
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Finance
Mortgage, auto loan, investment, retirement, sales tax, and tip calculators to plan your money decisions.
16 calculatorsHealth & Fitness
Body, nutrition and wellness calculators including BMI, calories and pregnancy planning.
8 calculatorsMath
Percentage, fraction, algebra and general-purpose math calculators for students and engineers.
16 calculatorsDate & Time
Calculate your age, date differences, working days and countdowns.
6 calculatorsConversions
Convert between units of length, weight, temperature, currency and more.
6 calculatorsAuto
Fuel economy, gas trip cost, and car lease calculators for everyday driving and road trips in the U.S.
6 calculatorsConstruction
Concrete, paint, and tile calculators for homeowners and contractors planning projects.
6 calculatorsEducation
GPA, grade, and test score calculators for U.S. students, parents, and teachers.
10 calculatorsCooking
Recipe scaling, kitchen unit conversions, oven temperatures, and food math.
9 calculatorsTravel
Flight time, time zones, currency conversion, and trip planning calculators.
9 calculatorsTech
Bandwidth, file size, hex/binary, password strength, and developer-friendly calculators.
9 calculatorsScience
Physics, chemistry, and engineering calculators for students and pros.
9 calculatorsBusiness
Markup, margin, breakeven, ROI, and small-business math calculators.
9 calculatorsPets
Dog age, cat age, pet food portion, and animal-related calculators.
9 calculatorsReal Estate
Cap rate, rental yield, mortgage affordability, property tax, and house-hacking calculators.
6 calculatorsSports
Running pace, marathon training, cycling speed, swimming pace, and heart rate zone calculators.
6 calculatorsPopular right now
From the blog
Pythagorean Triples: Patterns, Generators, and Why They Matter
A Pythagorean triple is three integers (a, b, c) with a² + b² = c². There are infinitely many — and they follow surprisingly clean patterns.
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The section formula generalizes the midpoint formula. Here is how to find the point that divides a segment in any ratio — internally or externally.
MathThe Distance Formula vs the Pythagorean Theorem: They Are the Same Thing
The distance formula looks complicated but it is just the Pythagorean theorem dressed in coordinate notation. Here is the connection.
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Ratios, rates, and proportions all compare two quantities — but each has a specific meaning. Here is how to tell them apart and use each correctly.
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For normal data, 68% of values fall within 1 SD of the mean, 95% within 2 SDs, and 99.7% within 3 SDs. Here is why, and how to use it.
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The Pythagorean theorem has hundreds of proofs. Here are three of the cleanest: by area, by similar triangles, and by algebra.