Reverse Percent
Reverse a Price Raise: 25% Up, What Was It?
A subscription says "you've been upgraded, value +25%, now $125." What was the honest cost? Countless people subtract 25% of 125 and get $93.75 — and they are wrong. Reversing an increase is a division, not a subtraction. Check the exact original in the calculator.
The mistake that trips everyone
If $100 rises by 25%, you get $125. To go back, you must undo that multiplication: $125 ÷ 1.25 = $100. Taking 25% off the new price ($31.25) wrongly lands at $93.75. The difference is the tax you pay for solving a reverse problem like a forward one.
The divide-by-1+percent rule
Turn the percentage into its decimal and add one, then divide:
- 25% → 0.25 → denominator 1.25
- 40% → 0.40 → denominator 1.40
- Divide the current price by that denominator.
An item now $49 at 40% above cost was $49 ÷ 1.40 = $35.
Why this matters for real budgets
Reversing an increase correctly is the difference between negotiating from a real baseline and arguing with a phantom. When a vendor announces "we raised rates 30% and your new bill is $143," the old bill was $110, not the $100 a naive reverse suggests. The percent-change mode and a little division keep your mental books honest.
Apply it to discounts, taxes and growth
The same reverse works everywhere: pre-tax price from a tax-inclusive total, pre-sale price from a discounted one, and the underlying revenue behind a "member milestone +50%." Memorize one-line "÷ 1 + percent" and you never recompute it again.