What is the formula for percentage decrease?

Percentage decrease = (old value − new value) ÷ old value × 100. The change is always measured against the value you started from.

What if the new value is bigger?

Then the decrease is negative, which is an increase. The calculator tells you this and reports the percentage increase instead — the formula is the same either way.

Why divide by the original value and not the new one?

A percentage change describes how far the value moved relative to where it began. Going from 200 to 100 is a 50% decrease (100 ÷ 200), while going back from 100 to 200 is a 100% increase (100 ÷ 100) — same gap, different baselines.

Arithmetic & Factors

Percentage Decrease Calculator

From a starting value to a new one — see exactly how big the drop is as a percentage, with each step of the calculation written out.

Your numbers

Starting value

New value

Worked solution

Percentage decrease

25%

240 fell to 180

Going from 240 to 180 is a 25% decrease: the value lost 60, which is 25 out of every 100 of the original.

The working

3 steps

Find the change
Subtract the new value from the starting value.
change = 240 − 180 = 60
Compare the change to the original
Percentages are always measured against where you started — never against the new value.
60 ÷ 240 = 0.2500
Convert to a percentage
Multiplying by 100 turns the ratio into “out of 100”.
0.2500 × 100 = 25%
Starting value
240
New value
180
Change
60
Multiplier
× 0.7500

Works instantly in your browser — nothing is uploaded, and the URL keeps your numbers so you can share the exact worked example.

Where percentage decrease shows up

Price drops, discount codes, falling sales, weight loss, battery drain — any “it used to be X, now it is Y” question is a percentage decrease. The three-step method (find the change, divide by the original, multiply by 100) works for all of them, and it is the same method used for percentage increase, just with the sign flipped.