Find a proportion
Use Percentage Calculator for part-of-whole questions and reverse percentage checks.
Calculators
Everyday math and financial calculations with clear assumptions.
These calculators are organized around the decision you need to make, not just a formula name. Use the percentage tools for proportions and changes, the money tools for discounts, tips, and compound growth, and the date tool when the distance between two calendar dates matters. Every result is calculated in your browser and shows the assumptions or substituted method beside the answer.
Similar-sounding percentage tasks are kept separate because their inputs and meanings differ. “What is 15% of 80?” is a proportion, “increase 80 by 15%” applies a rate to a starting value, and “how much did 80 change to 92?” compares two observed values. Choosing the matching workflow prevents the most common denominator and interpretation mistakes.
Choose the right calculation
Compare two values
Use Percentage Change when you know a starting and ending value and need direction plus magnitude.
Apply a rate
Use Percentage Increase, Discount, or Tip Calculator when a rate changes a known starting amount.
Before relying on a result
- Confirm which value is the starting value or denominator.
- Check rounding, compounding frequency, tax, contribution timing, and date-boundary assumptions.
- Treat financial examples as planning math, not personalized financial, tax, or legal advice.
7 tools
Compound Interest Calculator
Estimate a future balance and interest earned from a starting principal, annual rate, time period, and compounding schedule. The projection updates instantly in your browser.
Open tool →Date Duration Calculator
Calculate the calendar years, months, and days between two dates plus exact total days, full weeks, weekdays, and weekend days. Include the end date when your count needs both endpoints.
Open tool →Discount Calculator
Calculate the sale price and amount saved from any percentage discount. Optionally add sales tax after the discount to estimate the final checkout price.
Open tool →Percentage Calculator
Calculate a percentage of a number, find what percent one value is of another, or measure percentage increase and decrease. Results update instantly with no signup required.
Open tool →Percentage Change Calculator
Calculate the percentage increase or decrease between a starting value and an ending value. See the signed percentage, numeric difference, direction, and substituted formula instantly.
Open tool →Percentage Increase Calculator
Increase any non-negative value by a percentage, or measure the percentage increase from a starting value to a higher ending value. Results include the increase amount and multiplier.
Open tool →Tip Calculator
Calculate tip amount, total bill, and the equal per-person share with common tip presets. The calculator starts at 20% and one person, then updates as you type.
Open tool →