The calculator for everything, in one place.
Finance, math, health and everyday calculators in one place. Fast, free and simple.
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See all →Scientific calculator
Free online scientific calculator: sine, cosine, tangent, root, power, log, ln, π and parentheses.
Paycheck (take-home)
Estimate US take-home pay after federal income tax, FICA and state tax.
Mortgage
Calculate your monthly mortgage payment (PITI) and total interest for a US home loan.
401(k)
Project your 401(k) balance with annual contributions, employer match and growth.
Compound interest
See how your money grows over time with monthly contributions and an evolution chart.
BMI
Calculate your Body Mass Index (BMI) and see the WHO classification.
Interactive lessons
A calculator hands you the number. These lessons show you why — with a guess that exposes your intuition, a simulator you drag, and a lesson that goes against common sense. They are built here and exist nowhere else.
The 8th wonder of the world
Guess what $200/month becomes in 30 years, watch the snowball grow in an animated chart, and see the cost of waiting.
Start → DebtThe debt that never ends
Paying every month while the balance stays put isn't your imagination. Find the invisible line between paying and progressing.
Start → HealthWhy diets stall
Only 7% of your burn comes from the gym. See your metabolism from the inside and why the scale slows down.
Start →By category
Finance
32 calculatorsMath
27 calculatorsHealth
16 calculatorsConversion
14 calculatorsStudents
9 calculatorsDate & Time
9 calculatorsConstruction
8 calculatorsPhysics
11 calculatorsEvents
5 calculatorsStatistics
6 calculatorsEveryday
15 calculatorsFood
5 calculatorsSports
10 calculatorsChemistry
5 calculatorsWeather
4 calculatorsTech / IT
10 calculatorsPractical guides
See all →Learn how the math works: direct formulas and examples, linked to the calculators.
How to calculate compound interest
The compound interest formula with examples and why time makes money grow.
How to calculate percentage
Learn how to calculate percentages: X% of Y, increase, discount and change.
BMI: what it is and how to calculate
Understand Body Mass Index, the formula, the WHO ranges and its limitations.
Simple vs compound interest
The difference between simple and compound interest, with formulas and a side-by-side example.
How to calculate the average (mean)
The arithmetic and weighted mean, with examples, and how it differs from the median.
How to calculate a tip
How to calculate a tip, how much to give and how to split the bill.