Time
Percentage Change Calculator
Find the percent increase or decrease between two numbers. Say you charged $50/hr and now charge $65/hr: this tool tells you that's a +30% raise. It also works the other way, applying a percent change to a value or finding what percent one number is of another.
No sign-up and no account: everything runs in your browser, and nothing gets uploaded.
1. From A to B
Tidied result
Enter both values to see the change.
2. A changed by D%
3. What is D% of A
How do I calculate percentage increase between two numbers?
Subtract the old value from the new value, divide by the old value, then multiply by 100: percent change = (new − old) / old × 100. Say you charged $50/hr and raised your rate to $65/hr. That's (65 − 50) / 50 × 100 = +30%. The calculator above does this instantly for any two numbers in either direction, and it tells you in plain words whether it's an increase or a decrease, so you never have to eyeball the sign.
Why is percent change from zero undefined?
Percent change divides by the starting (old) value, so when that value is zero the formula becomes "divide by zero." That has no defined result: it isn't a very large number or a zero, it's simply undefined. If you went from charging $0 (a free trial period, say) to charging $50, the absolute change is a clear +$50. But there's no meaningful percentage to attach to it, because there was nothing to measure the increase against. The calculator above shows the absolute change in that case and explicitly says the percentage is undefined, instead of showing a broken "Infinity%" or "NaN%" result.
Is a change from 50 to 65 the same percent as 65 to 50?
No, percentage change is asymmetric. Going from 50 to 65 is +30% (a 15-unit increase over a base of 50), while going from 65 back down to 50 is about −23.08% (the same 15-unit decrease, but now measured over a larger base of 65). The absolute difference is identical either way. But because percent change is always calculated relative to the starting number, a bigger starting number spreads the same absolute change over a smaller percentage. This matters for freelancers tracking rate changes: raising your rate by X% and then cutting it by the same X% won't bring you back to where you started.
How do I apply a percent change to a rate or find what percent one number is of another?
Use mode 2 above when you already know the percent and want the resulting value: for example, a $200 project fee cut by 15% becomes $170. Use mode 3 when you want to know what a given percentage of a number actually is: for example, a 12% referral fee on an $850 invoice is $102. Both modes calculate live as you type, and neither needs a submit button.
How do I calculate percentage increase between two numbers?
Percent change = (new − old) / old × 100. For example, going from $50/hr to $65/hr is (65 − 50) / 50 × 100 = +30%. Use the calculator above to do this instantly for any two numbers.
Why is percent change from zero undefined?
Percent change divides by the starting value. When the starting value is zero, that division is undefined. There's no meaningful percentage to attach to the change, even though the absolute change is still a real number.
Is a change from 50 to 65 the same percent as 65 to 50?
No. 50 to 65 is +30%, but 65 to 50 is about −23.08%. Percent change is always measured against the starting number, so the same absolute difference produces a different percentage depending on which direction you're calculating.
How do I apply a percent change to a value, or find what percent one number is of another?
Use mode 2 above to apply a signed percent to a starting value (e.g. $200 changed by −15% = $170). Use mode 3 to find what a percentage of a number is (e.g. 12% of $850 = $102). Both calculate live as you type.