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Cash Back Calculator

Enter a purchase amount and a cash back rate to see how much you earn back and what the purchase effectively costs.

  • Free
  • No sign-up
  • Updated for 2026

Purchase & rate

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Enter a purchase amount and cash back rate to see your reward.

Worked example

With these example inputs:

  • Purchase amount$500
  • Cash back rate2%

Effective cost: $490

  • Cash back earned$10
  • Purchase amount$500

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What this cash back calculator does

This calculator shows your effective cost after cash back. You enter a purchase amount and a cash back rate. The tool then works out what you earn back. So you see the true cost of the buy. It also shows the cash back earned. The result uses the currency you choose.

How cash back works

Cash back is a small reward on a purchase. A card or app pays back a percent. So part of your spend comes back to you. It lowers the real cost of the buy. The rate is often one to five percent. This tool puts a figure on it.

How it is calculated

The tool takes your purchase amount. It works out the cash back at your rate. It then subtracts that from the price. So a higher rate cuts the cost more. The result is your effective cost. The calculator does the math for you.

What the result tells you

The result shows your effective cost. A five hundred buy at two percent costs four hundred ninety. A higher rate lowers it. A bigger purchase raises it. So it shows what you really pay. It is a straightforward figure.

The purchase amount

Your purchase amount is what you spend. It is the price before any reward. A bigger purchase earns more back. So this number sets the base. Use the total you plan to pay. It is the base the rest builds on. Enter your purchase amount.

The cash back rate

Your cash back rate is the percent you earn. It is set by your card or app. A higher rate gives more back. So this number drives the reward. Use the rate for that category. Some cards pay more on certain buys. Enter your cash back rate.

The cash back earned

The tool also shows the cash back earned. It is the money that comes back. Here it is ten on a five hundred buy. So you see the reward in plain dollars. A higher rate lifts it. It is the gap you save.

Why effective cost matters

The effective cost is the true price you pay. It nets out the reward you earn. So it helps you compare offers fairly. A big cash back rate can beat a discount. It shows the deal in real terms. Use it to judge a card or sale.

How to use it

Enter your purchase amount first. Add your cash back rate. Read the effective cost in your currency. Then see the cash back earned. Compare a few rates. Try a different card. Use it to pick the best reward.

The limits of this calculator

It has a few clear limits. It uses one rate on the whole buy. Real cards may cap the reward. Some have tiers or rotating categories. It ignores fees and interest. So treat the figure as a guide. So check your card's terms.

A final tip

Use this to see the real cost of a buy. Remember cash back is not free money. Carrying a balance can wipe out the reward. Pay the card in full each month. A reward only helps if you avoid interest. Do not spend more to earn more. A smart buy beats a big reward.

Frequently asked questions

How is cash back calculated?

Multiply the purchase by the cash back rate. A 2% rate on a 500 purchase earns 10 back, so the effective cost is 490.

Does cash back make a purchase free money?

Only if you would have spent anyway and pay the balance in full. Carrying a balance means interest can quickly outweigh any cash back earned.