Free Online Calculators

Calculators that run on your computer — BMI, calories, loans, percentages, ages, dates, units. Instant results. Nothing uploads. Works on bad wifi or no wifi.

Instant calculators for everyday math — BMI, calorie needs, loan payments, compound interest, mortgage amortization, GPA, tip splits, discounts, age, date differences, and unit conversions. Every calculation runs in the browser with no data sent to a server, so you can plug in real financial or health numbers without worrying about how they are stored or tracked. Results appear as you type. The full calculator collection is below.

Math

Percentage Calculator

Calculate percentages: what is X% of Y, X is what % of Y, and percentage change.

Scientific Calculator

Free online scientific calculator with trig, logarithms, exponents, and more. Supports keyboard input.

Fraction Calculator

Add, subtract, multiply, and divide fractions. See step-by-step solutions with simplified results.

Finance

Loan Calculator

Calculate monthly payments, total interest, and view a full amortization schedule for any loan.

Mortgage Calculator

Calculate monthly mortgage payments with principal, interest, taxes, and insurance. See a full amortization schedule.

Compound Interest Calculator

Calculate compound interest with monthly contributions. See how your savings grow over time with a visual chart.

Tip Calculator

Calculate tip amount, total bill, and per-person split. Preset and custom tip percentages.

Discount Calculator

Calculate discount savings, final price, and optionally add tax. Supports percentage and fixed amount discounts.

Salary Calculator

Convert between annual, monthly, biweekly, weekly, and hourly pay. Estimate take-home pay after federal taxes.

Invoice Generator

Create professional invoices and download as PDF. Add line items, tax, and your business details.

Health

BMI Calculator

Calculate your Body Mass Index. Supports metric and imperial units with health category breakdown.

Calorie Calculator

Calculate your daily calorie needs based on age, weight, height, and activity level.

Personal

Age Calculator

Calculate your exact age in years, months, and days. See your next birthday countdown.

GPA Calculator

Calculate your semester and cumulative GPA. Add courses, select grades, and see your grade point average instantly.

Reference

Unit Converter

Convert between units of length, weight, temperature, volume, speed, and more.

Date Calculator

Calculate the number of days between two dates, or add and subtract days from a date.

Time

Stopwatch & Timer

Stopwatch with lap times and countdown timer with alarm sound. Precision timing using requestAnimationFrame.

Pomodoro Timer

Focus timer with 25-minute work sessions and 5-minute breaks. Track your productivity.

Frequently asked questions

Are the financial calculations accurate enough for real decisions?: The loan, mortgage, and compound-interest calculators use standard actuarial formulas and are accurate for planning purposes. For legally binding contracts, verify outputs with your lender or a licensed financial advisor.
Do you store the numbers I enter?: No. All calculator inputs live only in your browser tab. Nothing is logged, stored, or associated with your account.
Can I share a calculation result with someone?: Most calculators keep inputs in the URL query string, so you can copy the URL from your address bar to share a pre-filled result. Check the address bar after entering values — if it updates, the link is shareable.