Percentage and Everyday Math Calculators: Tips, Discounts, and More
Almost every bit of everyday money math is a percentage wearing a disguise. A tip, a sale price, sales tax, a raise, a test score — all of them come down to "a part out of 100." Learn the one formula underneath and the rest is just knowing which part you're solving for. Here's the map of free tools for each situation, grouped by what you're actually trying to work out.
The one idea underneath all of it
A percentage is a part out of 100, and the base formula is (part ÷ whole) × 100. Everything below is that formula rearranged. If you want the full walkthrough with worked examples, start with how to calculate a percentage, or jump straight to the percentage calculator for a quick answer. To swap between percentages, decimals, and fractions, the decimal to percent converter handles the conversion.
Increases and decreases
When something goes up or down — a price, a salary, a follower count — you want the percentage change, measured against the original value. Our guide to calculating percentage increase and decrease covers the formula and the reversal trap, and the percent change calculator gives the answer with the up-or-down sign handled for you.
Discounts and sale prices
"30% off" is the most common percentage most people meet. The trick is knowing whether you want the saving or the final price. Here's how to calculate a discount step by step, and the discount calculator gives you the sale price instantly. Adding tax on top? The sales tax calculator finishes the job.
Tips
Splitting a restaurant bill and tipping is percentage math under pressure, usually while everyone's waiting. Our guide to calculating a tip shows the mental shortcuts, and the tip calculator works out the tip and the split per person.
| If you want to… | Use | Full guide |
|---|---|---|
| Find a percent of a number | Percentage calculator | How to calculate a percentage |
| Measure an increase or decrease | Percent change calculator | Percentage increase & decrease |
| Work out a sale price | Discount calculator | How to calculate a discount |
| Tip and split a bill | Tip calculator | How to calculate a tip |
How to pick the right one
Ask what you already know and what you're missing. Have a number and a percent, and want the piece? That's the percentage calculator. Comparing a before and an after? Percent change. Shopping? Discount, then tax. Eating out? Tip. Every tool here is free, runs in your browser, and never asks you to sign up.
Start with the basics
If percentages have always felt slippery, begin with how to calculate a percentage — it's the foundation every other tool on this page is built on. Once that clicks, the rest is just knowing which number you're looking for.
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