Percentage Increase Calculator

Everything hinges on the base. The change is measured against the starting value, never the ending one: that's why an increase and its reverse decrease don't match. Keep percentage change apart from percentage-point change too: a conversion rate moving from 2% to 3% is a one-point change and a 50% increase at once. And for values that start at or below zero, the percentage is undefined; the absolute change is the honest number to report.

With this month's and last month's figures already sitting in a Ferra table, a change column keeps every row's percentage current as new data lands.

Give it the before and the after. It returns the percentage change, positive for growth, negative for a drop, alongside the absolute change, the raw difference between the two numbers.

A metric moves from 250 to 300. Absolute change: 300 − 250 = 50. Divide by the original value, 50 ÷ 250 = 0.20, then multiply by 100 for a 20% increase.

Run it downhill and the base flips. Falling from 300 back to 250 is a change of −50 against a base of 300: −50 ÷ 300 ≈ −16.7%. That asymmetry is why a 20% gain followed by a 20% loss never returns home, 250 grown 20% is 300, but 300 cut 20% is 240.

Dividing by the wrong base, the new value instead of the original, is the error that shows up most. Right behind it: confusing percent change with percentage points. A conversion rate moving from 10% to 12% rises 2 percentage points but jumps 20%, since 2 ÷ 10 = 0.20. Reports that mix the two can overstate or understate change dramatically.

Relative size is the point. A $5,000 raise on a $50,000 base and a $5,000 bump on a $500,000 base are the same dollars and wildly different events, 10% versus 1%, and percentages are what put them in honest proportion. That's the lens for comparing revenue growth across products of different sizes, or for judging if this month's jump in signups is out of line. It also puts a raise into terms you can weigh against inflation, and does the same for a price hike or a fee change.

Small bases lie. Going from 2 customers to 8 is a 300% increase, which sounds dramatic and means almost nothing. When the original value is small, report the absolute change alongside the percentage. And for a series of changes over time, chain them by multiplying, or use a CAGR, rather than adding the percentages up.

One-line formula, endless ways to misread it. These habits keep percentages honest.