Deposit profit calculator

What you can set

You enter the amount, the annual interest rate, the term in months (from 1 to 120), how interest is capitalised and the tax rate on interest. The model covers a deposit with a fixed rate and no top-ups or withdrawals during the term. It is not a full savings account calculator with promotions, top-ups and a variable rate.

Gross interest, tax and net profit

Gross interest is the interest before tax. Tax on interest depends on your country and the rules vary, so you enter the rate that applies to you; 0% shows the gross result. For reference, in Poland the tax on account interest is 19% (capital gains tax) and the bank withholds it automatically. Net profit is gross interest minus tax, the amount that actually adds to your balance. The calculator shows these values separately, together with the amount you will have at the end of the term.

Capitalisation at the end of the term and monthly

With capitalisation at the end of the term, interest is calculated on the amount you deposited and paid once. With monthly capitalisation, each month's interest is added to the balance and earns interest itself from the next month, so at the same rate gross interest is slightly higher. Because tax is charged at every capitalisation, net profit grows more slowly than gross.

Interest rate and term

A deposit rate is quoted per year, even when the deposit runs for a shorter time. A 3-month deposit at 5% earns, with capitalisation at the end of the term, gross interest of 5% ÷ 4 = 1.25% of the amount deposited.

Average net profit per month

This is the net profit divided by the number of months. It is an average and does not mean the bank pays interest out every month.

Worked example

10,000 for 12 months at 5%. With tax at 0%, net profit equals gross interest. Capitalisation at the end of the term: gross interest 500.00, net profit 500.00, amount at the end 10,500.00. Monthly capitalisation: gross interest 511.64, net profit 511.64.

With an illustrative tax rate of 20%: capitalisation at the end of the term gives gross interest of 500.00, tax of 100.00, net profit of 400.00 and 10,400.00 at the end. Monthly capitalisation (tax at every capitalisation) gives gross interest of 509.27, tax of 101.91 and net profit of 407.36. For reference, with Poland's 19% the results are 500.00 / 95.00 / 405.00 (end of term) and 509.38 / 96.85 / 412.53 (monthly).

What the calculator does not include

We don't include promotions, top-ups or withdrawals during the term, a variable rate, quarterly or annual capitalisation, foreign-currency deposits or breaking a deposit early. The real result depends on the bank, which may count interest in days and round differently.

Capitalisation at the end of the term: gross interest = amount × (annual rate ÷ 100) × (number of months ÷ 12), paid once; tax is calculated once on the total interest. Monthly capitalisation: each month interest = balance × annual rate ÷ 12, tax is charged on that month's interest, and the net profit goes back into the balance.

Tax is the rate you enter in the form: enter the rate that applies in your country (0% gives the gross result). The calculator rounds the tax up to the next cent, a convention taken from the Polish rules (in Poland the rate is 19%); your bank or country may round differently. We calculate in equal months, at a fixed rate and with no top-ups. This is a model: a real deposit may count interest in days and round differently.