Use this percentage change calculator to find how much any value grew relative to where it started. Enter the old value and the new value; the result appears instantly. This page covers the formula, two step-by-step examples, and the mistakes people make most often. This calculator is for informational use only; double-check any value that affects a real decision.
Results update as you type.
Returns a signed percent so increases and decreases are distinguishable, plus the absolute delta and a plain-English direction.
Percentage increase = (New − Old) / Old × 100
| Symbol | Name | Unit | Description |
|---|---|---|---|
| old_value | Old value | number | The starting value. Must not be zero. |
| new_value | New value | number | The ending value to compare against the old value. |
This percentage change calculator lets you estimate the change between an old value and a new value with a plain-English direction. Use it when the percentage matters more than the raw difference.
Calculating a Percentage Increase
Use this calculator any time a number goes up and you want to know how big that jump really was. The raw difference tells you the amount; the percentage tells you the size relative to where you started. Both answers matter, but they answer different questions. When you need to add a set percentage on top of a base amount — like a tip on a restaurant bill — the [Tip Calculator](/calculators/tip-calculator) is the faster choice for that direction.
These three terms cover the same underlying math but point in different directions. Picking the right one means your answer is easy to read and hard to misinterpret.
A percentage increase measures how much a value grew. Use it when the new value is larger than the old one — a price hike, a salary raise, a rising test score.
Percentage increase = ((New value − Old value) / Old value) × 100The result is always positive when the new value is higher.
A percentage decrease measures how much a value dropped. The new value is smaller than the old one — a discount, a falling temperature, a shrinking budget. The Discount Calculator handles this case directly when you're working with sale prices.
Percentage decrease = ((Old value − New value) / Old value) × 100The subtraction is flipped compared to the increase formula. That keeps the answer positive, so a 15% drop reads as 15, not −15.
Percent change handles both directions with one formula. A positive result means the value grew; a negative result means it fell.
Percent change = ((New value − Old value) / Old value) × 100This is the same formula as percentage increase. The difference is that you don't flip the subtraction, so the sign carries the direction for you.
| Your situation | Use this |
|---|---|
| You know the value went up | Percentage increase |
| You know the value went down | Percentage decrease |
| You're not sure of the direction, or you want one formula for both | Percent change |
If you run this calculator and get a negative result, the value actually decreased. Switch to the percentage decrease formula to get a clean positive readout of the drop.
The most common error is putting the numbers in backward. You always divide by the old value, not the new one. If a stock goes from $50 to $60, the base is $50. Using $60 as the base gives you 16.7% instead of the correct 20%.
Correct: ((60 − 50) / 50) × 100 = 20%
Wrong: ((60 − 50) / 60) × 100 = 16.7%If the old value is zero, the formula breaks. You cannot divide by zero, so the result is undefined. This comes up when a product had no sales last month but sold 200 units this month. There is no meaningful percentage increase from nothing — report the change as an absolute number instead.
A negative starting value makes the formula work but the result feels backward. Say a company lost $400 one quarter and earned $100 the next. The formula gives −125%, which looks like a decrease even though the business improved. When your old value is negative, add a note explaining the direction of change so the number is not misread.
These two are not the same. If a savings rate rises from 4% to 5%, that is a 1 percentage-point increase. The percentage increase in the rate itself is 25%, because 1 is 25% of 4. Use "percentage points" when comparing two percentages; use "percentage increase" when comparing two regular values.
Two increases do not add up the way whole numbers do. A 10% increase followed by another 10% increase is not a 20% total increase. The second 10% applies to the already-raised amount, so the real total is 21%.
After first 10%: 100 × 1.10 = 110
After second 10%: 110 × 1.10 = 121
Total increase: ((121 − 100) / 100) × 100 = 21%, not 20%Use this calculator any time a number goes up and you want to know how big that jump really was. The raw difference tells you the amount; the percentage tells you the size relative to where you started. Both answers matter, but they answer different questions. When you need to add a set percentage on top of a base amount — like a tip on a restaurant bill — the Tip Calculator is the faster choice for that direction.
Prices change constantly, and a percentage makes comparisons fair. A $5 jump on a $20 item hits harder than a $5 jump on a $500 item. Use the calculator when comparing price changes across products, budgets, or time periods.
Examples:
A raise sounds better as "10% more pay" than "$400 extra per year." Use the calculator to check whether an offer matches what you expected, or to translate a dollar amount into a percentage your employer quoted.
Examples:
Health metrics only make sense when you track them over time. A single number tells you where you are; a percentage increase tells you how far you've come.
Examples:
Markets quote gains as percentages because the raw dollar amount depends on how much you started with. Use the calculator to check whether a reported return matches the numbers on your statement.
Examples:
Traffic, sales, and signups all grow in ways that need context. A percentage makes it easy to compare months, campaigns, or channels on equal f…