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Reverse percentage calculator
What a price was before tax was added or a discount taken off, worked back from what it is now. Free, with no account or uploads.
Find the number before a percentage
Type the number now and the percentage that was added or taken off. It is divided out, not taken off again.
The percentage was
AddedTaken off
After was added, it is
Before the %
85
Before 20% was added, it was 85.
How it is worked out
- Adding 20% multiplies by 1 + 0.2 = 1.2
- So divide by it instead: 102 ÷ 1.2 = 85
- Check: 85 + 20% = 102
- Taking 20% of 102 off would give 81.6, which is not the same: the percentage was of the number before, not after.
Answers that do not end are rounded to this many places, halves up.
Worked out exactly on your device, rounded only to show it. Nothing you type is sent anywhere.
A little help along the way
Follow these steps. Every option is explained underneath. Everything is worked out in your browser; nothing is sent anywhere.
- Say what you want to work outA percentage of a number is the usual. The others are what percent one number is of another, a change, adding or taking off a percentage, the number before a percentage, and marks.
- Fill in the numbersType them into the sentence. You can type 1,250, ₹85, 12.5% or even 1/3.
- Read the answer and the workingThe answer is said in a sentence, with the steps on your own numbers and a grid of 100 squares.
Questions people ask
- How do I find a price before tax was added?
- Divide by 1 plus the tax rate. A price of 118 with 18% tax was 118 ÷ 1.18 = 100 before the tax.
- Why not just take 18% off the price with tax?
- Because the tax was 18% of the price before, not of the price after. Taking 18% off 118 gives 96.76, which is wrong; the page shows both so the difference is plain.
- Can it undo a discount too?
- Yes. Choose Taken off: a price of 80 after 20% off was 80 ÷ 0.8 = 100 before.
This page is the Percentage calculator, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the Percentage calculator's own page.
Read the step-by-step guide