Calculate percentage increase or decrease from a positive starting value. See the formula, worked examples and how percentage points differ.
Enter the amount you started with and the amount you ended with, in the same units. The answer is the rise or fall measured against the starting amount, rounded to two decimals.
It answers one question: by what proportion of its old self did an amount move? That is the right measure for a price rise, a salary increase, a drop in traffic, or any before-and-after figure where the starting amount is the natural reference point.
The arithmetic runs in your browser and nothing you type is sent anywhere. It compares two numbers you already have; it does not project a trend, and the output is general information rather than financial advice.
Percentage change = (new value − original value) ÷ original value × 100. A positive answer is labelled an increase, a negative answer a decrease, and two identical values return 0.00% (no change).
Under the result, the tool prints the substitution it made. For 80 to 100 the steps read (100 − 80) ÷ 80 × 100 = 25.00%. The signed figure appears there, while the headline result states the direction in words.
Rounding is to two decimals for display only; the division itself is unrounded. That matters at the edges: 1200 to 1200.004 shows 0.00% increase, not "no change", because the change is real but too small to survive two decimal places. The "no change" wording is reserved for an answer that is exactly zero.
A zero original value is refused because the formula would divide by zero: there is no proportion of nothing. If you went from 0 to 60, report the absolute increase of 60 instead, or state the new level on its own.
A negative original value is refused for a different reason: the sign of the answer would stop matching the direction of travel. From −200 to −100 the figure improves by 100, yet the formula returns −50%, which reads as a decrease; from −100 to −200 it returns +100%, which reads as growth while things got worse. Rather than print a contradictory label, the tool asks for a positive start. For debts, losses and sub-zero temperatures, quote the absolute change instead.
A negative new value is fine, since the direction stays unambiguous. A balance of 50 becoming −10 returns 120.00% decrease: it fell by 60, which is 120% of the 50 you started with.
The gap is 20, and 20 ÷ 80 is 0.25, so the result is 25.00% increase. The denominator is the amount you started with, never the amount you ended with.
The gap is −50, and −50 ÷ 250 gives 20.00% decrease. Swapping the two numbers does not swap the percentage: 200 back up to 250 is a 25.00% increase, because the reference point moved.
From 60 to 0 the answer is 100.00% decrease, and that is the largest decrease possible while the figure stays non-negative. Anything you measure can lose all of itself once, but not twice.
A fall and the rise that undoes it are not the same percentage, because the second one is measured from the smaller number. Lose 20% and you are at 80; to get back to 100 you need to add 20 to 80, and 20 ÷ 80 is 25%. So a 20% drop takes a 25% rise to recover.
The rule is: to undo a fall of d, you need a rise of d ÷ (1 − d). Put either pair of numbers into the boxes above and the tool will confirm it.
| Fall | Rise needed to recover | Check with these values |
|---|---|---|
| 10% | 11.11% | 90 to 100 |
| 20% | 25.00% | 80 to 100 |
| 50% | 100.00% | 50 to 100 |
It works the other way too: a 25% rise is undone by a 20% fall, as 125 back to 100 shows.
Successive percentage changes multiply; they do not add. Two 10% increases on 100 give 110 and then 121, and entering 100 and 121 returns 21.00% increase, not 20%. The extra point is the second rise applying to the first rise as well as to the original.
Combine them with (1 + a) × (1 + b) − 1 rather than a + b. Three 5% rises on 100 reach 115.76, reported as 15.76% increase rather than 15%. The effect cuts both ways: a 50% rise then a 50% fall takes 100 to 150 and on to 75, an overall 25.00% decrease, even though the two percentages look like they should cancel.
When the thing that moved is itself a percentage, there are two honest answers and they are far apart. A rate going from 20% to 25% has risen by 5 percentage points, and it has risen by 25% in relative terms, since (25 − 20) ÷ 20 × 100 = 25. Both describe the same event.
Say which one you mean: "rose 25%" and "rose 5 points" are the same fact with very different force. Our guide to percentage change and percentage points works through more cases.
Two numbers, one comparison. There is no series input, no annualising, no CAGR, no inflation adjustment and no chart. Both entries must be finite numbers; blanks and text return a message naming the field, and a result too large to represent returns Result is too large. Please use smaller values. rather than an infinity. Nothing is stored, and editing either box clears the previous answer.
Yes for an increase, with no upper bound: 40 to 200 is a 400% increase. A decrease can also pass 100%, but only if the new value is negative, as with 50 to −10.
Percentage change has a direction and divides by the starting value. Percentage difference compares two values with no before and after, dividing by their average, so it gives one figure whichever order you take them in. This tool computes the first.
Multiply by 1 plus the change as a decimal. A 30% rise on 40 is 40 × 1.3 = 52, and you can confirm it by entering 40 and 52 here.
This tool fixes the display at two decimals. A spreadsheet shows whatever its cell format allows, so the change from 2.4 to 3.1, which is 29.1666…%, may appear there as 29% while this page shows 29.17%. The underlying value is the same.
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Reviewed October 1, 2026. Calculation methods and corrections.