Free calculator

Free financial calculators

Free tools to understand your debt and your savings. No sign-up, and your figures never leave your browser.

Debt and credit cards

What paying the minimum on your card really costs With your real balance and rate: how many years it would take, how much extra you would pay, and the payment below which the debt never goes down at all.

Saving and investing

How much your savings grow with compound interest With monthly deposits and all five compounding frequencies. Matches the SEC calculator at investor.gov to the cent, and explains why other calculators disagree.

These calculators are free, need no sign-up, and do the maths inside your browser: none of the figures you type ever leave your device. They use exactly the same maths as the AI Money app, so the number you see here and the number you would see inside the app are the same.

Most of the financial calculators on the internet live on the websites of banks and lenders, who have no incentive for the result to frighten you. These do the opposite: they give you the figure as it comes out, even when it stings. It usually stings.

How they are built

Three things that matter to us and that other calculators do not always get right:

The rate conversion is the exact one. Turning an effective annual rate into a monthly one is not dividing by twelve: it is (1 + rate)^(1/12) − 1. The difference looks small and over a multi-year debt it is hundreds of dollars. Dividing by twelve is only valid for nominal rates, and here you can choose which one you have.

Nothing is stored. The calculation happens in your browser with JavaScript. There is no form, no sign-up and no server receiving your balance. You can disconnect from the internet after the page loads and they will keep working.

They are the same formulas as the app. Not a simplified version for the web. If the two numbers ever disagreed, that would be a bug on our side and we would want to hear about it.

Are the calculators free?

Yes, all of them. There is no sign-up, no usage limit and nothing to download in order to use them.

Do you store what I type?

No. The calculation happens entirely in your browser and none of the figures you enter are sent to any server or saved anywhere.

Where do the formulas come from?

They are the same ones the AI Money app uses to project debts and savings, not a simplified version. Each calculator explains the method step by step so you can check it in a spreadsheet if you want to.

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Updated August 14, 2026