Sale price → original retail
- Choose “After discount” (reverse decrease) mode.
- Enter the sale price and the percent taken off.
- Copy the original value for tags, markdown audits, or spreadsheets.
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Work out everyday percentage math in one place: a percent of a number, how much two numbers differ in percent terms, growth or decline from an old value to a new one, reverse the last step after a discount or raise, plus markup and profit margin on cost.
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A percentage calculator answers practical questions about parts of a whole, relative growth or decline, comparing two numbers in percent terms, and working backward to a value before a percent was applied.
Percentage calculations are mathematical operations. Results may show minor floating-point rounding (< 0.01%) due to binary floating-point arithmetic — use with appropriate precision for financial reporting.
A percentage is a way of writing a ratio with 100 as the reference (so 18% means eighteen per hundred). In real life you use that idea for discounts, taxes, tips, grades, survey results, and KPIs like 'traffic is up 12% this week.'
This page bundles the calculations people look up over and over: take a percent of a number, express one number as a percent of another, bump a value up or down by a percent, measure percent change from an old baseline to a new result, compare two numbers with a symmetric percentage difference, and reverse the last step to recover an original amount.
Percent change always needs a clear baseline; 'percentage difference' is a symmetric alternative when you only have two peers. Reverse-percentage modes undo the last multiplier — handy for 'sale price was X after Y% off, what was retail?'
Select the question you are really asking (percent of, what percent, increase, decrease, change, difference, or reverse).
Enter values in any order you like; commas are stripped automatically. Leave fields empty until you are ready — the result appears when the mode has enough valid input.
The large number is the main answer. Under it, a short line shows the formula in words and numbers. Extra rows (multiplier, verification) are there when they help confidence.
Use Copy result for a one-line summary you can paste into email, spreadsheets, or notes. On phones and some desktops, Share opens the system share sheet.
Common real-world scenarios where this tool saves time.
Quickly find how much a percent-off saves, or check whether a '20% extra free' claim matches the numbers on the shelf.
Estimate interest-style growth, pay rises as a percent of salary, or how much a bill changed month to month.
Turn points earned into a percent of the total, or see how much you need on a final to hit a target average.
Report week-over-week or year-over-year change, or compare two funnel counts with a difference measure that does not pick sides.
Understand a percent change in weight or pace — always pair with how the baseline was chosen.
Step-by-step chains that connect related tools for common tasks.
Input
Mode: What is X% of Y? · Y = 200 · X = 15Output
30Multiply 200 by 15 ÷ 100. That is the same as 200 × 0.15. Use this for tips, taxes, or any 'take this percent of a total' problem.
Input
Mode: What percent is X of Y? · Part = 43 · Whole = 60Output
71.67%(43 ÷ 60) × 100 ≈ 71.67%. Common for quizzes, assignments, and progress bars.
Input
Mode: Percent change · Old = 42,000 · New = 50,400Output
+20%((50,400 − 42,000) ÷ 42,000) × 100 = 20%. The sign tells you direction; the size tells you how sharp the move was versus last period.
Input
Mode: Percentage difference · First = 40 · Second = 60Output
40%|40 − 60| ÷ ((|40| + |60|) ÷ 2) × 100 = 20 ÷ 50 × 100 = 40%. Handy when two channels or cohorts are peers, not 'before and after.'
Input
Mode: Value after −X% decrease is known · After discount = 80 · Discount = 20%Output
Original ≈ 10080 ÷ (1 − 20/100) = 80 ÷ 0.8 = 100. Use this when you only know the sale price and the percent taken off.
Below is a compact reference for every mode on the tool. Increase and decrease modes multiply the starting value by a factor built from the percent. Reverse modes divide by that same factor to undo the step. Percent change keeps the original value in the denominator so results are comparable when the baseline moves.
Formula
Percent of: R = (p ÷ 100) × Y. What percent: R = (X ÷ Y) × 100. Increase: R = Y × (1 + p/100). Decrease: R = Y × (1 − p/100). Percent change: R = ((new − old) ÷ |old|) × 100. Percentage difference: R = (|A − B| ÷ ((|A| + |B|) ÷ 2)) × 100. Reverse after increase: original = new ÷ (1 + p/100). Reverse after decrease: original = new ÷ (1 − p/100).Each row matches a mode in the calculator at the top of the page.
| Question | Formula | Quick example |
|---|---|---|
| What is X% of Y? | R = (X ÷ 100) × Y | 15% of 200 → 30 |
| What percent is X of Y? | R = (X ÷ Y) × 100 | 30 of 200 → 15% |
| Increase Y by X% | R = Y × (1 + X/100) | 200 + 15% → 230 |
| Decrease Y by X% | R = Y × (1 − X/100) | 200 − 15% → 170 |
| Percent change (old → new) | R = ((new − old) ÷ |old|) × 100 | 150 → 180 → +20% |
| Percentage difference | R = (|A − B| ÷ ((|A| + |B|) ÷ 2)) × 100 | 40 and 60 → 40% |
| Original before +X% | original = new ÷ (1 + X/100) | 120 after +20% → 100 |
| Original before −X% | original = new ÷ (1 − X/100) | 80 after −20% → 100 |
| Markup on cost | sell = cost × (1 + markup/100) | Cost 50 + 40% → sell 70 |
| Margin on sell | sell = cost ÷ (1 − margin/100) | Cost 50, 30% margin → sell ≈ 71.43 |
Symmetric percentage difference is not the same as picking an 'old' and 'new' — use percent change when the story is truly sequential.
| Related tool | Use this tool when | Use related tool when |
|---|---|---|
| Discount Calculator | You need a general-purpose percentage tool covering multiple modes: percent of, percent change, reverse, markup, and margin. | You specifically need to calculate sale price, savings amount, or final price after a % off discount with a focused interface. |
| Tip Calculator | You want to manually compute a custom tip percentage or understand the underlying formula. | You want to split a restaurant bill between multiple people and see per-person amounts alongside the tip. |
| Fraction Calculator | Your value is already expressed as a percentage and you need to compute an increase, decrease, or reverse. | Your value is expressed as a fraction (like 3/4 or 7/8) and you need to add, subtract, multiply, or divide fractions before converting to a percentage. |
If an interest rate goes from 3% to 5%, that is +2 percentage points. The relative increase is about 66.7% because (5 − 3) ÷ 3 ≈ 0.667 — a much bigger headline.
Always label which value is the reference (old, budget, forecast). If neither is clearly first, percentage difference mode may be clearer than percent change.
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Divide X by Y, then multiply by 100: (X ÷ Y) × 100. Example: 15 out of 60 → (15 ÷ 60) × 100 = 25%. If Y is 0, the question is undefined.
New value = original × (1 + rate ÷ 100). The increase amount is original × (rate ÷ 100). Percent change from old to new is ((new − old) ÷ |old|) × 100.
New value = original × (1 − rate ÷ 100). The amount removed is original × (rate ÷ 100). If the rate is negative, you are effectively increasing the value.
Percent change picks an original and asks how far the new value moved relative to that baseline. Percentage difference here is symmetric: it compares the gap between two numbers to their average magnitude, so neither has to be the 'before' value.
If a value went up by r%, you reached new = original × (1 + r/100), so original = new ÷ (1 + r/100). If it went down by r%, new = original × (1 − r/100), so original = new ÷ (1 − r/100) when that divisor is not zero. Example: $80 after 20% off → $80 ÷ 0.8 = $100.
Yes where the math still makes sense. For increase/decrease modes, a negative percent flips the direction. For 'what percent is X of Y,' the sign comes from the numbers themselves.
Relative change divides by the original. When the original is 0, that division has no useful meaning — only the absolute difference (new − 0) is informative.
Percentage points measure the simple gap between two percentages. Example: a rate moving from 10% to 15% is +5 percentage points. The relative increase from 10% to 15% is 50% because (15 − 10) ÷ 10 = 0.5.
20% of 500 = 500 × (20 ÷ 100) = 100. To find any percentage of a number, multiply the number by the percentage divided by 100. Other quick examples: 10% of 500 = 50; 15% of 500 = 75; 25% of 500 = 125.
Multiply the bill total by the tip rate ÷ 100. For a 15% tip on $48: 48 × 0.15 = $7.20. For 20%: 48 × 0.20 = $9.60. Quick mental shortcut: 10% of $48 is $4.80 — double it for 20%, add half for 15%. Use the 'What is X% of Y?' mode on this calculator for any tip amount.
Divide the discounted price by (1 − discount ÷ 100). Example: item is $72 after 20% off → 72 ÷ 0.80 = $90 original. Use the 'Reverse after X% decrease' mode to find this instantly. This is useful when a price tag shows the sale price but not the original retail price.
Percentage difference = (|A − B| ÷ ((|A| + |B|) ÷ 2)) × 100. Example: comparing 40 and 60 → |40 − 60| = 20; average = 50; 20 ÷ 50 × 100 = 40%. This is a symmetric comparison — neither value is the 'baseline.' Use percent change instead if one value clearly comes before the other in time.
Percent change = ((new − old) ÷ |old|) × 100. If revenue grew from $20,000 to $25,000: ((25,000 − 20,000) ÷ 20,000) × 100 = 25% increase. If it fell to $15,000: ((15,000 − 20,000) ÷ 20,000) × 100 = −25%. The sign indicates direction; the magnitude shows how sharp the move was.
Discount % = ((original price − sale price) ÷ original price) × 100. Example: item was $80, now $56 → ((80 − 56) ÷ 80) × 100 = 30% off. Use the 'What percent is X of Y?' mode with X = discount amount and Y = original price, or 'Percent change' with old = original and new = sale price.
Your numbers stay on your device. This calculator does not upload inputs or results to our servers.
Outputs use the same floating-point math as your browser. For everyday percentages that is plenty; for audited financial statements, follow your organization’s rounding and disclosure rules.
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Reviewed by EverydayTools Editorial Team on 2026-05-21.
20% of 500?
500 × 0.20 = 100
Percent change?
((new − old) ÷ |old|) × 100
After 20% off?
Original = sale price ÷ 0.80
Find a portion: multiply Y by X ÷ 100.
Enter values below—your result appears here instantly.
Numbers stay on your device. For tips use Tip Calculator; for margin on revenue see Profit Margin Calculator.
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