Compound Interest Calculator

Compound interest means profit is added to the deposited amount, and the next interest is charged on the increased amount. Monthly contributions accelerate growth.

Each month: Amount = Amount × (1 + Rate ÷ 12) + Contribution

Time is the main factor: the longer compound interest works, the stronger the growth becomes, because interest is charged on interest.

Invest 50,000 UAH upfront and add 5,000 UAH at the end of every month at 14% per year. After 5 years the account holds ≈ 531,256.12 UAH: your own contributions are 350,000.00 UAH (50,000 + 60 × 5,000) and interest is ≈ 181,256.12 UAH. These are the values the calculator shows when the page opens.

Now regular contributions only: 5,000 UAH a month from zero at 14% per year. After 10 years you get ≈ 1,295,344.56 UAH from 600,000.00 UAH contributed; after 20 years ≈ 6,505,830.03 UAH from 1,200,000.00 UAH. Twice the time gives about five times the result — that is interest earning interest.

With simple interest the gain is the same every year: S = P × (1 + r × n). With compound interest each period’s gain is calculated on the already grown amount. For a 100,000 UAH deposit at 14% per year with no contributions:

The longer the term, the wider the gap: over 5 years compounding adds 30,560.98 UAH more, over 20 years 1,238,027.01 UAH more.

Capitalization means adding accrued interest to the deposit. With m compounding periods per year: S = P × (1 + r ÷ m)^(m × n). Here is what 100,000 UAH at 14% per year grows to in 10 years:

The calculator uses monthly compounding: each month the amount is multiplied by (1 + rate ÷ 12) and then the contribution is added. The effective annual yield of 14% compounded monthly is about 14.93%.

Divide 72 by the annual rate in percent to estimate the years to double. At 14% that is about 5.1 years (the exact figure with monthly compounding is 4.98 years). At 6% about 12 years, at 10% about 7.2 years, at 20% about 3.6 years. The rule is approximate and most accurate for rates of 6–10%.

Without contributions:

S = P × (1 + r ÷ 12)^(12 × n)

With a monthly contribution at the end of each month (as the calculator does):

S = P × (1 + i)^m + PMT × ((1 + i)^m − 1) ÷ i

Here i = rate ÷ 12, m is the number of months, P is the starting amount and PMT is the monthly contribution. For the example above: 50,000 × (1 + 0.14 ÷ 12)^60 + 5,000 × ((1 + 0.14 ÷ 12)^60 − 1) ÷ (0.14 ÷ 12) ≈ 531,256.12 UAH.

The calculator shows a nominal result: hryvnia at the rate you enter. Prices rise over time, so the purchasing power of savings grows more slowly. You can estimate the real rate as (1 + nominal rate) ÷ (1 + inflation) − 1. Illustrative example: at 14% per year and 8% inflation, the real return is about 5.6%, not 6%. Use current official figures for taxes and inflation — the calculator does not include them.