Percentage Change Calculator

Percentage changes trip people up more than they should. Your rent goes from $450 to $490 a week and you know it hurts, but is that a 9% increase or an 11% increase? This tool does the maths instantly so you don't have to second-guess yourself.

It works in three directions. Plug in two numbers and get the percentage change between them. Or start with a number and a percentage to find the result. You can even work backwards from a final value to figure out what the original was before the change happened.

A real example with real numbers

Say you're negotiating a pay rise. Your current salary is $78,000 and your employer offers $83,500. Pop both numbers in and you'll see that's a 7.05% increase. Now you've got a concrete figure to compare against CPI (which ran at about 3.6% over the past year) or the average wage growth rate of 4.1%. A 7.05% bump sounds generous until you realise you haven't had a raise in two years, which means you're really only 3.3% ahead after inflation.

Works for price tracking too. That $1,200 fridge you were eyeing dropped to $899 during an EOFY sale? That's a 25.1% discount. Compare it against the retailer's claimed "30% off" and you'll spot the inflated original price trick straight away.

Getting the most out of this calculator

Use the mode toggle at the top to switch between the three calculation types. If you're comparing prices over time, run the numbers in "% change between two numbers" mode. If you're budgeting a raise or a discount, "new value after % change" gives you the dollar figure directly. And if someone tells you a price went up 15% to reach $345, the "original value" mode works backwards to tell you it was $300 before the hike.

Tip: bookmark this page. Percentage questions pop up more than you'd think, from splitting bills to checking whether that "sale" is actually worth your time.

Reverse percentage examples

This is the one people usually butcher in their head. If a jacket is now $120 after a 20% discount, the original price was not $144 because you guessed. It is $120 divided by 0.8, which gives you $150. Same deal with pay rises, fee increases, and sale stickers.

Another common one: if a bill rises 12% to $448, the original was $448 divided by 1.12, which is $400. Working backwards properly saves a lot of fake bargains and bad budgeting.

Percentage change vs percentage points

These get mixed up constantly in finance, news, and property talk. If a mortgage rate moves from 5.80% to 6.10%, that is a 0.30 percentage point increase. But the percentage change is roughly 5.17% because you are measuring the increase relative to the original 5.80%.

Use percentage points when comparing rates, margins, or poll numbers. Use percentage change when comparing how much bigger or smaller a number became.

Frequently asked questions

What's the difference between percentage change and percentage points?

If an interest rate moves from 4% to 5%, that's a 1 percentage point increase but a 25% change. They measure different things. This calculator gives you the percentage change, which is what most people need when comparing prices, salaries, or investment returns.

Does the order of the numbers matter?

The original value always goes first. If you swap them around, you'll get a different result because you're measuring the change from a different starting point. Going from 100 to 150 is a 50% increase, but going from 150 to 100 is a 33.3% decrease.

Why do I get a negative number?

A negative result means the value dropped. If your portfolio went from $12,000 to $10,800, the calculator shows -10% because that's how much value you lost. Negative isn't bad in every context though. A -15% on your power bill means you saved money.