Percentage Change Calculator (Free). Volume & rate shifts, done right

How to read it

Two kinds of "percent"

The number "5%" behaves very differently when it's a rate than when it's a change. Mixing them up is how a small move gets reported as a big one. Here's how to keep them straight.

Use the left card for volumes

Anything counted in whole units — spend, clicks, impressions, leads, revenue. The relative % change tells you how much bigger or smaller this period is versus last: from 1,000 to 1,250 clicks is +250 and +25%.

Use the right card for rates

Anything already expressed as a percentage — CTR, CVR, ROI, margin. Moving from 2% to 3% is +1 percentage point, but a +50% relative jump. Both are true; each answers a different question.

Points for the board, % for the trend

When reporting a rate, lead with percentage points so no one thinks CTR "grew 50%" out of nowhere. Keep the relative % for spotting momentum — it's the honest way to compare a small rate's movement to a large one's.

Watch the zero baseline

Going from 0 to any number is an infinite percentage increase — mathematically true, but useless in a report. When the previous period is zero, quote the absolute change instead and note it started from nothing.

A quick honesty note

This is pure arithmetic on two numbers you type in — no rounding tricks, no smoothing. The two calculators are fully independent, so you can compare a volume and a rate at the same time without them interfering.

About this tool

Did it really move, or did it just look like it?

The Percentage Change Calculator answers the question behind every "how did we do?" — how much a metric shifted between two periods, in plain terms. Enter last period and this period, and it gives you both the absolute change and the relative percentage change at once, so you can report the move accurately instead of guessing at the maths.

The second calculator exists because rate metrics are where reporting goes wrong. A CTR that goes from 2% to 3% hasn't grown "1%" — it's up 1 percentage point, or 50% relative. Keeping the two separate is the difference between a report people trust and one they don't.

Percentage Change Calculator

Volume & Spend

Rates & Percentages