Calculating your original amount is straightforward once you know the Reverse Percentage formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Reverse Percentage Calculator.
What is Reverse Percentage?
The Reverse Percentage calculation tells you your original amount from a few simple inputs. The figure you are solving for here is the original amount.
The Reverse Percentage formula
This calculation combines several inputs through a multi-step method rather than a single one-line formula. Enter the values below and the calculator resolves each step in order. The inputs it needs are:
- Final amount — a number. Example: 120.
- Percentage — a percentage, such as an annual rate. Example: 2%.
- Change applied — one of: Was increased by, Was decreased by. Example: Was increased by.
How to calculate it step by step
- Write down the final amount (for example, 120).
- Write down the percentage (for example, 2%).
- Choose the change applied (for example, Was increased by).
- Apply the formula above to get your original amount.
- Double-check the result with the Reverse Percentage Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Final amount | 120 |
| Percentage | 2% |
| Change applied | Was increased by |
| Original amount | 100.00 |
With final amount of 120, percentage of 2% and change applied of Was increased by, the original amount works out to 100.00.
Example 2
With final amount of 240, percentage of 2% and change applied of Was increased by, the original amount works out to 200.00.
| Result | Value |
|---|---|
| Original amount | 200.00 |
Example 3
With final amount of 60, percentage of 2% and change applied of Was increased by, the original amount works out to 50.00.
| Result | Value |
|---|---|
| Original amount | 50.00 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Reverse Percentage Calculator does it instantly, for free, with the formula and a worked example built in.
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