Reverse percentage: how to find the original number

Divide the total by (1 + percent / 100). If 1,200 already includes 20%, the original is 1,200 / 1.2 = 1,000. Subtracting 20% from the total is wrong: it gives 960.

Original number—

Formula: Total / (1 + Percent / 100)

Open the full tool: Percentage calculator →

Divisor chart for reverse percentages

Percent includedDivisorShare of total1,200 without it
5%÷ 1.054.76%1,142.86
10%÷ 1.19.09%1,090.91
12%÷ 1.1210.71%1,071.43
13%÷ 1.1311.5%1,061.95
15%÷ 1.1513.04%1,043.48
18%÷ 1.1815.25%1,016.95
20%÷ 1.216.67%1,000
22%÷ 1.2218.03%983.61
25%÷ 1.2520%960
30%÷ 1.323.08%923.08
50%÷ 1.533.33%800

What it is for

It answers “what was it before the increase?” Price with tax → price before tax, price with markup → cost, salary after a raise → before it. The percentage was applied to the original number, so you remove it by dividing, not subtracting.

If the number was reduced

For a sale price the formula is similar: original = sale price / (1 − discount/100). If an item costs 750 after 25% off, it was 750 / 0.75 = 1,000. In the calculator enter a negative percentage: −25.

How much of the total is the percentage

In a total that includes 20%, the added part is 20/120 = 16.67% of the total. That column of the chart lets you pull tax or markup out of a total directly.

FAQ

How do I find the number before a percentage was added?

Divide the total by (1 + percent/100). For example, 1,150 including 15% → 1,150 / 1.15 = 1,000.

How do I find the price before a discount?

Sale price / (1 − discount/100). 750 after 25% off → 750 / 0.75 = 1,000.

Why can’t I just subtract the percentage?

The percentage was taken from the smaller original, while subtracting takes it from the larger total. 1,200 − 20% = 960, but the original was 1,000.

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