Percentage / Tip Calculator

Percentage math shows up constantly in small, situational forms — splitting a restaurant bill with tip across a group, working out a discount at checkout, calculating a commission on a sale, or figuring out what percentage one number represents of another. This tool covers all of those directions: tip and bill-splitting, straightforward “what is X% of Y,” percentage increase/decrease between two numbers, and “what percentage is A of B,” each with its own simple input rather than forcing every calculation through the same generic form.

Why local processing matters here

Most percentage math is genuinely low-stakes, but this tool gets pulled up in some specific, real moments where the numbers matter more than they look: working out a commission split during an active negotiation, calculating a discount on a deal before quoting a client, or splitting a bill in a way that reveals exactly what each person spent. None of those numbers are catastrophic if seen by someone else, but they’re also not anyone else’s business, and there’s no reason a simple percentage calculation needs a live number typed into a server to get an answer back. Everything computes instantly in the browser.

How to use it

1. Choose the calculation type first — tip/bill split, basic percentage of a number, percentage increase/decrease, or “what percent is A of B” — since each uses a slightly different input layout.
2. For tip and bill splitting, enter the bill total, choose a tip percentage (or enter a custom one), and set the number of people splitting the bill — the tool shows both the tip amount and each person’s total share.
3. For a basic percentage calculation, enter the percentage and the number, and it returns the result immediately as you type.
4. For percentage increase or decrease, enter the original and new values — useful for things like a price change, a raise, or a discount — and the tool returns both the dollar/unit difference and the percentage change.
5. For “what percent is A of B,” enter both numbers directly — common when you know a part and a whole and need the percentage that connects them, like a completion rate or a pass rate.
6. Adjust rounding if you need a clean number for a real payment (rounding a tip to the nearest dollar, for instance) versus an exact figure for a calculation that needs precision.

Common situations this solves

• Splitting a restaurant bill with tip evenly, or unevenly if people ordered noticeably different amounts.
• Working out the final price of an item after a percentage discount, or the pre-discount price if you only know the sale price and the discount percentage.
• Calculating a commission or bonus that’s defined as a percentage of a sale or deal value.
• Figuring out a percentage change between two numbers — a price increase, a metric that moved period over period, a weight change.
• Determining what percentage a part represents of a whole, like a score out of a total, or how much of a budget has been spent so far.

FAQ

Why does 20% off followed by another 20% off not equal 40% off?

Sequential percentage discounts apply to the reduced price each time, not the original — 20% off $100 leaves $80, and a further 20% off $80 is $64, not $60. Compounding always produces a smaller total discount than simply adding the two percentages together, which is a common source of confusion at checkout.

What’s the difference between percentage increase and percentage points?

Percentage increase describes a relative change (going from 50 to 60 is a 20% increase), while “percentage points” describes an absolute difference between two percentages (going from 50% to 60% is a 10 percentage point increase, but still a 20% relative increase). Mixing these up is one of the most common sources of miscommunication with percentage figures, especially in reporting contexts.

How should I split a tip fairly if people ordered very different amounts?

The tool supports both even splitting (dividing the total tip equally regardless of who ordered what) and proportional splitting, where each person’s share is based on their portion of the total bill — worth deciding which convention the group prefers before splitting, since the two methods can produce noticeably different individual totals.

Why do I get a different answer calculating “20% of 50” versus “50% of 20”?

You actually don’t — both equal 10, since percentage multiplication is commutative (20% × 50 = 50% × 20). If your two calculations are producing different results, double-check which number is meant to be the percentage and which is the base value, since it’s easy to swap them by mistake.

Is there a standard tip percentage I should use?

Tipping conventions vary significantly by country and even by service type, so there’s no single correct number — the calculator defaults to a few common presets (15%, 18%, 20%) as a starting point, but a custom percentage field is there for anywhere those defaults don’t apply.

How do I reverse-calculate the original price before a discount, if I only know the sale price?

Use the percentage increase/decrease mode in reverse — enter the sale price as the “new” value and set the known discount percentage, and the tool works backward to the original pre-discount price.

If the percentage work you’re doing is actually a pricing or margin decision for a business rather than a one-off calculation, the Markup vs Margin Calculator handles that distinction more directly, since markup and margin percentages are calculated differently even though they sound similar.