FINANCEVELIX / Investment calculators
Savings interest calculator (monthly savings and fixed deposits)
FINANCEVELIX / CRYPTO
Crypto tools
See how much interest a monthly savings plan or a one-off fixed deposit earns by the end of its term, before and after tax. Choose simple interest or a compounding frequency, and enter the tax rate on interest that applies to you.
Savings interest calculator
Use the same currency for every price, fee and amount. Changing this label does not convert values.
FINANCEVELIX / Your calculation
Your calculation
Enter your assumptions, then select Calculate.
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FINANCEVELIX / Method
How savings interest is calculated
With simple interest, each deposit earns the annual rate ÷ 12 for every month it stays in the account, and interest does not earn interest. For a monthly deposit D over n months: interest = D × (rate ÷ 12) × n × (n + 1) ÷ 2. For a fixed deposit P: interest = P × rate × n ÷ 12.
Example: 1,000,000 a month for 12 months at 5% simple interest earns 1,000,000 × 0.05 ÷ 12 × 78 = 325,000 before tax, because the first deposit is held for 12 months and the last for 1.
With compounding, interest is added to the balance and earns interest itself. A rate compounded m times a year becomes an equivalent monthly rate, (1 + rate ÷ m)^(m ÷ 12) − 1, and the balance grows by that rate every month. CFPB's example: 1,000 at 5% compounded once a year becomes 1,102.50 after 2 years.
Tax = interest before tax × your tax rate. On a monthly plan, interest is a smaller share of the deposits than the stated rate, because later deposits stay in the account for a shorter time.
Frequently asked questions
Why is the interest on monthly savings lower than the annual rate?
Only the first deposit stays for the whole term. In the example, 12,000,000 deposited at 5% earns 325,000, about 2.71% of the deposits, because the average deposit is held for 6.5 months.
What is the difference between simple and compound interest?
Simple interest is paid only on the money deposited. Compound interest is also paid on interest already earned, so the balance grows faster, and more so the more often interest is compounded.
Which tax rate should I enter?
Enter the rate that applies to your interest under your country's rules and your account type, or leave it at 0 to compare amounts before tax. This calculator does not set any country's rate for you.