Choose a direction
Percent change compares a new value with an original value. The original is the reference point and belongs in the denominator. Swapping the two values changes that reference, so the reverse comparison is not generally the negative of the first.
A change from 40 to 50 is an increase of 10 units. Those 10 units are one quarter of 40, but only one fifth of 50. Both statements describe the same gap using different bases.
Keep the sign until the end
Subtract original from new, divide by original, then multiply by 100. For positive starting values, a positive result means growth and a negative result means decline.
A starting value of zero cannot be used as a denominator. Describe such a change in units instead of inventing a percentage. Negative starting values also need careful interpretation; this calculator uses the signed original value.
Percentage points are another measurement
A rate rising from 12% to 15% rises by 3 percentage points. Relative to 12%, its percent increase is 25%. Label which measurement you mean when discussing rates.
For several periods, multiply growth factors rather than adding percentage changes. A 10% rise followed by a 10% fall leaves 99% of the original amount.
LET’S WORK IT THROUGH
A weekly total grows from 320 to 368. What is the increase?
- 368 − 320 = 48.
- 48 ÷ 320 = 0.15.
- 0.15 × 100 = 15%.
THE ANSWERThe total increased by 48 units, or 15%.
YOUR TURN
A small check for understanding.
What is the change from 90 to 72?
Reveal the answer
−20%. The loss of 18 is divided by the original 90.
Now try your own numbers.
The percent change includes input guidance and the limits of its supported calculations. Use it alongside the method above.
Open Percent change ↗A note on precision: preserve exact fractions where possible and round numerical results at the end. Found an unclear step? Prepare a correction report.