Calculators

Everyday calculation tools

27 tools in this category.

Each calculator answers one number question and shows the arithmetic on the page. The Percentage Calculator does three jobs: 15% of 80 is 12, 12 is 30% of 40, and increasing 200 by 10% is 220. Percentage Change compares two finished values, so 80 to 100 is a 25% rise and 100 back to 80 is a 20% drop. Discount, sales tax, and tip start from a price. Age counts calendar years, months, and days, including leap days, and it does not divide the span by 365.

Use these when a spreadsheet is more than the job needs. The numbers stay in the browser tab. Loan, mortgage, wage, and tax results are estimates from the figures you type. They are not financial, tax, medical, or legal advice. A “what percent” question with a whole of 0 is rejected, because that divides by zero. Date tools count calendar days or business days between two dates. The unit converter covers length, weight, and temperature, not currency, area, or volume.

Useful starting points

Percentage Calculator

Find percentages, increases, decreases and what percent one number is of another.

Percentage Change Calculator

Compare an original number with a new one and see the percent change. From 80 to 100 is a 25% rise; 100 back to 80 is a 20% drop. An original of 0 is rejected.

Discount Calculator

Take a percent off a price and see the amount saved and what you pay. Type plain numbers. A currency symbol is invalid, and a discount above 100% is rejected.

Age Calculator

Count years, months, and days from a birth date to today or a later date. An earlier date is rejected. Leap days follow the calendar, not a 365-day year.

Unit Converter

Convert length, weight, or temperature between units as you type. Currency, area, and volume are not included. A temperature below absolute zero is rejected.

Random Number Generator

Generate random integers or decimals with crypto.getRandomValues, including unique draws.

Tip Calculator

Split a bill by tip percentage and number of people, including the tip and the total per person.

Sales Tax Calculator

Add a sales tax rate to a price and see the tax amount and the final price.

Date Difference Calculator

Count the days between two dates, then see weeks and a calendar span in years, months, and days.

Compound Interest Calculator

See how a starting amount grows with compound interest, optional monthly contributions, and a simple-interest comparison.

Loan Calculator

Estimate the monthly payment, interest, and payoff schedule for a fixed-rate installment loan, including a personal loan.

Mortgage Calculator

Estimate principal and interest, optional housing costs, a 15-year and 30-year comparison, and an extra-payment payoff.

Auto Loan Calculator

Estimate a car loan payment from vehicle price, down payment, trade-in, tax, fees, and APR.

Home Affordability Calculator

Estimate a home price from income, debts, down payment, rate, and housing costs. This is a budget estimate, not an approval.

Debt Payoff Calculator

Estimate how long several debts take to pay off, and the interest, under a highest-interest or smallest-balance plan.

Credit Card Payoff Calculator

Estimate how long a card balance takes to pay off from the APR and the minimum or fixed payment you enter.

Savings Goal Calculator

Estimate the regular contribution that reaches a savings target from what you have already saved and a rate you choose.

Hourly Wage Calculator

Convert an hourly rate and a weekly schedule into weekly, monthly, and annual pay, or turn a salary into an hourly rate.

Paycheck Estimator

Estimate net pay from gross pay and the pre-tax, withholding, and post-tax amounts you enter.

Rent vs Buy Calculator

Compare estimated rent paid with the estimated cash cost and equity of buying over a period you choose.

Fuel Cost Calculator

Estimate fuel used and the cost of a trip from distance, fuel economy, and the price you enter.

Business Days Calculator

Count weekdays between two dates, and leave out any dates you exclude.

GPA Calculator

Calculate a credit-weighted GPA from letter grades or grade points on a common 4.0 map.

Square Footage Calculator

Multiply each room length by its width, then add the rooms. Totals are in square feet and square meters. It measures rectangles, not closets or triangles.

Aspect Ratio Calculator

Simplify a width and height into a ratio, or find the missing side from a ratio.

Time Calculator

Add or subtract hours and minutes, then read the total as hours, minutes, and total minutes.

Average Calculator

Find the mean, median, and mode of a list of numbers separated by commas or spaces.

Guide

How to Calculate Percentage

How to calculate a percentage: X% of a number, a number as a percent of another, and percent increase or decrease.

Guide

How to Calculate Age

Count age in years, months, and days from a date of birth using the civil calendar, including leap days.

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How to Calculate a Tip

Multiply the bill by the tip rate, add it to the total, and divide by the number of people when the check is shared equally.

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How to Add Sales Tax to a Price

Multiply a pre-tax price by the tax rate you type, round the tax to cents, and add it to the price.

Guide

How to Convert Length, Weight, and Temperature

Convert length and weight by a fixed factor, and temperature with the Celsius, Fahrenheit, and Kelvin formulas.

Guide

How to Count the Days Between Two Dates

Count midnights between two dates, then read weeks and a calendar span in years, months, and days.

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How to Generate a Random Number

Draw 1 to 200 integers or decimals between a minimum and a maximum. Unique mode works for integers only.

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How to Estimate a Fuel Cost

Divide distance by fuel economy, then multiply by the price and the number of trips.

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How to Calculate an Aspect Ratio

Divide width and height by their greatest common divisor, or find the missing side from a ratio.

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How to Add or Subtract Hours and Minutes

Add or subtract hours and minutes by converting both sides to minutes, then splitting the signed total back into hours and a remainder.

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How to Find the Mean, Median, and Mode

Find the mean, median, and mode of a comma-separated list. 1, 2, 3, 4 has a mean of 2.5 and no mode.

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How Compound Interest Grows Your Money

Compound interest adds growth onto a balance over time. See the monthly method this calculator uses, including an optional contribution.

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How a Loan Payment Is Calculated

An installment payment is estimated from the amount, annual rate, and term. A separate fee is not rolled into that payment.

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How a Mortgage Payment Is Estimated

A mortgage estimate starts from home price and down payment, then can add tax, insurance, HOA, and PMI.

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How to Estimate a Car Loan Payment

A car payment estimate starts from vehicle price, then subtracts down payment and trade-in after tax, fees, and add-ons.

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How a Home Price Estimate From Income Works

This estimate sizes a home price from income, debts, and a target ratio. It is not a promise of what you can safely buy.

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How to Compare Renting and Buying Costs

How to compare an estimated rent cost with an estimated buying cost for the same period.

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How to Plan a Debt Payoff

How a payoff timeline is estimated when more than one debt is being paid down.

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How Long a Credit Card Balance Takes to Pay Off

How long one card balance can take to pay off at a chosen payment.

Guide

How Much to Save for a Goal

At 0% interest, divide the gap between the target and what you have saved by the number of deposits.

Guide

How to Turn Hours or a Salary into Pay

How a yearly or weekly salary converts to an hourly rate, including overtime hours.

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What a Paycheck Estimate Includes

What this paycheck estimate includes, and which taxes and deductions it does not calculate.

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How to Calculate a GPA

How a 4.0 GPA is credit-weighted from course grades.

Guide

How to calculate square footage

How to calculate room area in square feet or square meters from length and width.

Guide

How to Count Business Days

How weekdays between two dates are counted, without treating that span as an age.

Text Tools

15 tools

Tools for writing and text processing

Developer Tools

23 tools

Format, encode, minify, and convert data in the browser

Image Tools

18 tools

Browser-based image and PDF tools

SEO & Utilities

12 tools

Links, slugs, QR codes, and passwords

AI Tools

6 tools

Prompt builders and writing tools, with optional Gemini AI