Investments

Compound Interest Calculator

This calculator projects the future value of an investment using compound interest, plus optional monthly contributions.

How we calculate

Each period, the accumulated balance earns interest, and that interest becomes part of the balance that earns interest in the next period.

M is the final amount, P is the principal, i is the periodic rate, n is the number of periods, and PMT is the periodic contribution.

M = P × (1 + i)ⁿ + PMT × (((1 + i)ⁿ − 1) / i)

R$ 1,000 with no contributions at 1% monthly for 12 months results in about R$ 1,126.83.

'Total invested' is what you put in; 'total interest' is what was earned on top of it.

Assumes a constant rate and fixed contributions. Does not account for inflation, fees, or taxes. Treat the result as an estimate.

Is compound interest always better than simple interest?

For investors, yes — returns compound on themselves over time.

How do I use an annual rate instead of monthly?

Select 'per year' in the rate field; the calculator converts it using compound interest math, not a simple division by 12.

Investments

Calculate returns using simple interest, without compounding.

Converters & indicators

Convert interest rates between monthly and annual using compound equivalence.

Investments

Simulate the net return of a CDB indexed to a percentage of the CDI, after tax.

Financial planning

Find out how long it takes to reach a financial goal with monthly contributions.

Methodology last reviewed: July 15, 2026

This result is an estimate and may not reflect every particularity of your situation.