How do I reverse a percentage?

Use whole = part ÷ percent × 100. If 60 is 75% of the whole, 60 ÷ 75 × 100 = 80. A percentage of zero cannot identify the original total.

How do I find the price before a discount?

Use the percentage paid, which is 100 minus the discount. Paying 200 after 20% off means 200 is 80% of the original, giving 250. For 100% off, the zero payment cannot uniquely recover the earlier price.

Does adding the discount back undo it?

No. Adding 20% to 200 produces 240 because that percentage uses the smaller base. Recovering a 250 original after 20% off requires dividing 200 by 0.8.

Can I use a percentage above 100 or a negative percentage?

Yes, for a stated numeric proportion with a nonzero percentage. This is algebra on the supplied part and rate; no currency, tax or institutional conversion is selected.

Reverse Percentage Calculator

When you know a part and the percentage it represents, divide by that percentage and multiply by 100 to recover the whole. This page starts with 200 as 80% of the total, giving 250. After a 20% discount you paid 80% of the original price, so enter 80 as the share paid. Adding 20% to the reduced price answers a different question.

200 is 80% of what number?250200 ÷ 80 × 100

Question

This number

Is this percent

The working
200 ÷ 80 × 100
Computed result
250

Change and difference are not the same thing. Going from 80 to 100 is a 25% increase, measured against where you started. But the percentage difference between 80 and 100 is 22.22%, because that one divides by the average of the two. Change has a direction; difference does not. Reports and spreadsheets mix these up constantly, which is why both are here as separate questions.

Margin and markup are the same profit over two different divisors. Something that costs 40 and sells for 100 earns 60 either way, but the margin divides that by the selling price and is 60%, while the markup divides it by the cost and is 150%. Margin can never pass 100%; markup has no ceiling. The profit margin question above reports both, each beside the number it divided by.

Common questions

How do I reverse a percentage?: Use whole = part ÷ percent × 100. If 60 is 75% of the whole, 60 ÷ 75 × 100 = 80. A percentage of zero cannot identify the original total.
How do I find the price before a discount?: Use the percentage paid, which is 100 minus the discount. Paying 200 after 20% off means 200 is 80% of the original, giving 250. For 100% off, the zero payment cannot uniquely recover the earlier price.
Does adding the discount back undo it?: No. Adding 20% to 200 produces 240 because that percentage uses the smaller base. Recovering a 250 original after 20% off requires dividing 200 by 0.8.
Can I use a percentage above 100 or a negative percentage?: Yes, for a stated numeric proportion with a nonzero percentage. This is algebra on the supplied part and rate; no currency, tax or institutional conversion is selected.

Browser double-precision arithmetic. Decimal results are rounded to twelve significant digits; safe integer results retain their full value. The formula shows the inputs used.