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Savings calculator

Project the future value of regular savings with compound interest, tax and inflation.

Input
Output

Savings calculator

Enter a starting deposit, a regular contribution, an annual interest rate and a number of years, and this tool projects the final balance with compound interest, the total amount you put in, and the total interest earned. Paste one line per scenario in the format deposit;contribution;rate;years to compare several savings plans side by side — for example a low-risk 3% account against a 7% investment plan over the same 20 years.

The options control how the math actually compounds. Contribution frequency sets how often the regular deposit is added — monthly, quarterly or annually — independently of compounding frequency, which sets how often interest is calculated and added to the balance. Contribution timing decides whether each deposit lands at the start or the end of its period; depositing at the start earns interest for that period too, so it always produces a slightly higher balance. Tax on interest withholds a percentage from every interest payment before it is reinvested, which is how a taxable account actually compounds. Annual inflation discounts the final balance back to today's purchasing power, shown alongside the nominal figure.

Every scenario also prints a year-by-year breakdown: the amount contributed that year, the interest earned that year, and the running balance — useful for spotting the year compounding starts to outpace your own contributions. Choose CSV output to paste the breakdown straight into a spreadsheet, or keep the readable text format for a quick check.

All calculations run locally in your browser using standard JavaScript arithmetic — nothing you type is uploaded anywhere. Copy the result, download it as a .txt file, or send the output back into the input to tweak a scenario further.

FAQ

What does the deposit;contribution;rate;years format mean?
Deposit is your starting balance, contribution is the amount you add each period, rate is the annual interest rate as a percentage, and years is the length of the plan. Separate the four values with semicolons, one scenario per line.
Why do contribution frequency and compounding frequency matter separately?
They model two different real-world schedules: how often you add money and how often the bank calculates interest. A monthly contribution with annual compounding behaves differently from monthly contribution and monthly compounding, even at the same nominal rate.
How is tax on interest applied?
The tax percentage is withheld from each interest payment before it is added back to the balance, so a taxed scenario compounds on a smaller reinvested amount — the same way a taxable savings account works.
What does the inflation-adjusted 'today's value' mean?
It divides the nominal final balance by the compounded inflation rate over the same number of years, showing what that future sum would be worth in today's money.
Are my numbers uploaded anywhere?
No. The calculation runs entirely in your browser using JavaScript — your figures never leave your device.