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Savings and Compound Interest Calculator

Explore how an initial capital and monthly contributions could accumulate under an assumed annual rate. You can add a goal to estimate the minimum monthly contribution.

Educational use. Figures are estimates, not professional advice or offers. Check the actual terms.

Read the full use notice

These tools are for educational purposes. Their results are estimates that depend on the inputs and the assumptions stated in each calculator.

They do not constitute financial, tax or legal advice, personalized recommendations, offers or contractual terms. Check actual costs and contracts and consult a qualified financial professional before deciding.

To the extent permitted by applicable law, we are not responsible for losses or damage arising from decisions made solely on the basis of these estimates. This notice does not exclude or limit rights or liabilities that cannot legally be excluded or limited.

Your data

Project your savings

Format

Currency

The indicated maximums are limits of this tool in USD.

Initial principal (USD)

From 0 to 1,000,000,000.00 USD.

Monthly contribution (USD at the end of each month)

From 0 to 10,000,000.00 USD.

Assumed annual rate (% annual)

Constant assumption from 0 to 100 %. You can write .99.

Term

Use years, months, or both; from 1 to 600 months.

Years

Months

Savings goal (USD, optional)

Blank means no goal. If used, it must be greater than 0 and up to 10,000,000,000.00 USD.

Summary

Your projected balance will appear here

Enter principal, contribution, rate, and term. The goal is optional.

A reproducible example in USD

Fixed editorial example in USD; the currency selector does not convert these figures.

With 1,000.00 USD initial, without contributions, an assumed annual rate of 12 % and 12 months, the projected balance is 1,126.84 USD. In the first month, the return is 10.00 USD (1,000 × 0.12 ÷ 12); it is added to the balance. Each subsequent month uses the new balance and rounds its return to the smallest unit of the chosen currency. If instead you start from zero and contribute 100.00 USD at the end of each month, the balance would be 1,268.25 USD after 12 months with the same rate. That first contribution earns no interest in the month it is made.

How it is calculated

The assumed nominal annual rate is divided by 12. Each month, the yield is calculated on the opening balance and rounded to the smallest unit of the chosen currency; then the contribution is added at the end of the month.
The final balance is the initial capital plus all contributions plus the accumulated yield. The table allows you to check each step.
If there is a goal, the minimum monthly contribution in smaller units is sought using the same simulation. For example, with 1,000.00 USD initial, 0% rate, 12 months and a 2,000.00 USD goal, 83.34 USD per month is needed: 83.33 USD would only reach 1,999.96 USD.

Assumptions and limits

1 to 600 months are allowed, initial capital from 0 to 1,000,000,000 main units of the chosen currency, monthly contribution from 0 to 10,000,000 main units, rate from 0 to 100% annually with up to two decimals and a positive goal up to 10,000,000,000 main units. A balance exceeding that limit is explicitly rejected. A goal may fall outside the allowed monthly contribution or balance.

This is an educational projection, not an offered yield or an investment recommendation. The rate is assumed to remain constant; the balance is not guaranteed. Inflation, taxes, commissions, rate changes or capital losses are not considered.