Every calculator you need, in one place.
Crictron Calculators gives you fast, accurate, ad-light tools for mortgages, loans, health, school, and everyday math — built to U.S. conventions ($ and imperial units) and free forever.
Quick percentage calculator
X is what percent of Y?
Need more modes (percent of a number, percent change)? Open the full percentage calculator.
All calculators
Pick a tool below — every calculator opens instantly, works on mobile, and needs no download.
Finance
Mortgage Calculator
Estimate your monthly mortgage payment, interest, and amortization schedule.
FinanceLoan Calculator
Calculate monthly payments and total interest on any personal or business loan.
FinanceAuto Loan Calculator
Work out your car payment including trade-in, down payment, and sales tax.
FinanceCompound Interest Calculator
See how savings and investments grow with compounding and contributions.
FinanceSales Tax Calculator
Find sales tax, total price, or the pre-tax price for any U.S. state rate.
FinanceDiscount Calculator
Find the sale price and savings for any percentage-off discount.
FinancePaycheck Calculator
Estimate your take-home pay after 2026 federal tax and FICA.
FinanceInflation Calculator
See how inflation affects the future value of money.
FinanceMargin Calculator
Calculate gross margin, markup, or a target selling price.
FinanceRoth IRA Calculator
Project your Roth IRA balance at retirement.
FinanceCD Calculator
Calculate certificate of deposit growth at maturity.
Math & Date
Percentage Calculator
Solve any percentage problem: percent of a number, percent change, and more.
MathAge Calculator
Find your exact age in years, months, and days from your date of birth.
MathDate Calculator
Calculate the days between two dates, or add/subtract days from a date.
MathGPA Calculator
Calculate your weighted grade point average from courses, grades, and credits.
MathFraction Calculator
Add, subtract, multiply, or divide fractions with automatic simplification.
MathTriangle Calculator
Solve a triangle's side, angles, and area with the Law of Cosines.
MathHours Calculator
Total weekly work hours, overtime, and estimated pay.
MathUnit Conversion Calculator
Convert length, weight, volume, and temperature units.
Why use Crictron Calculators?
Every tool on this site runs entirely in your browser: nothing you type is uploaded or stored, so your numbers stay private. Each calculator is built around the formulas professionals actually use — standard amortization math for loans and mortgages, the CDC's BMI formula for health tools, and the Mifflin-St Jeor equation for calorie needs — and is checked for accuracy before publishing.
Have a calculator you'd like to see added? Let us know.