How does compound interest work here?

Interest is calculated monthly at one-twelfth of the annual rate and added to the balance. The next month's interest is then calculated on the new, higher balance — this is compounding.

Is the rate nominal or effective (APY)?

It is nominal annual, divided by 12 each month. To use an APY, convert it first: nominal rate = 12 × ((1 + APY)^(1/12) − 1).

Are taxes and fees included?

No. The result is gross — before any taxes on interest income or account fees. Deduct those from the rate or final value as appropriate.

What if I have no initial deposit?

Set the initial deposit to 0. The calculator works entirely from the monthly contributions.

Can I share a calculation?

Yes. Use the share button to copy a link that reopens the calculator with the same inputs.

Savings Calculator

Enter an initial deposit, monthly contribution, annual interest rate, and number of years. The calculator shows the total future value, what you put in, and how much of it is interest.

Use it to see how a regular savings habit, combined with compound interest, grows into a future balance — and how much of that balance is earned interest versus your own contributions.

Future value

$41,872.85

Contributions Interest earned

Total contributions: $29,000.00
Total interest earned: $12,872.85

The result updates as you type. The bar splits the future value into your contributions (blue) and earned interest (amber) so you can see the power of compounding at a glance.

How does it work?

When the annual rate is 0%, the formula simplifies to FV = PV + PMT × n. Interest compounds monthly.

Future value of savings formula

FV = PV \cdot (1+r)^n + PMT \cdot \frac{(1+r)^n - 1}{r}

FV: Future value — the total balance at the end.
PV: Present value — the initial deposit.
PMT: Monthly contribution.
r: Monthly interest rate (annual rate ÷ 12 ÷ 100).
n: Number of months (years × 12).

A $5,000 initial deposit with $200/month at 6% annual interest over 10 years grows to about $42,435.

Method & sources

Interest compounds monthly at one-twelfth of the annual rate. Monthly contributions are made at the end of each month (ordinary annuity). The annual interest rate is nominal, not effective (APY).

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

Savings basics — U.S. Securities and Exchange Commission (Investor.gov), verified 2026-06-10

How we calculate

Interest compounds monthly at one-twelfth of the annual rate.
Monthly contributions are made at the end of each month (ordinary annuity).
The annual interest rate is nominal, not effective (APY).
Taxes, fees, and inflation are not included.
The currency shown follows the site language; the maths is the same in every market.
When the annual rate is 0% the future value is simply the sum of all contributions.

Rounding

All monetary outputs are rounded to two decimal places for display. The calculation uses full floating-point precision throughout.

What the calculator does

It applies the standard future-value formula for a growing annuity: your initial deposit earns compound interest every month, and each monthly contribution does the same from the date it is made. The result is the total pot at the end of the period.

How to use it

Enter the initial deposit (or 0 if starting from scratch).
Enter the amount you will add each month.
Enter the annual interest rate as a percentage.
Enter the number of years you plan to save.
Read the future value, total contributions, and total interest earned.

An example

A $5,000 deposit with $200 added monthly at 6% per year for 10 years grows to about $42,435. You contribute $29,000 ($5,000 + $200 × 120 months) and the rest — about $13,435 — is earned interest. That is the compounding effect in action.

Tips for better results

Even a small regular contribution makes a large difference over time — try increasing the monthly amount by $50 and see how the future value jumps.
The rate field is nominal annual. For a high-yield savings account, use the stated APY. For stocks, a historical average of 7–8% (inflation-adjusted) is often used as a rough guide.
Taxes on interest income are not included. For tax-advantaged accounts the displayed number is closer to reality.

When it is useful

Planning for a down payment, an emergency fund, retirement, or any other financial goal with a known time horizon.

FAQ

How does compound interest work here?: Interest is calculated monthly at one-twelfth of the annual rate and added to the balance. The next month's interest is then calculated on the new, higher balance — this is compounding.
Is the rate nominal or effective (APY)?: It is nominal annual, divided by 12 each month. To use an APY, convert it first: nominal rate = 12 × ((1 + APY)^(1/12) − 1).
Are taxes and fees included?: No. The result is gross — before any taxes on interest income or account fees. Deduct those from the rate or final value as appropriate.
What if I have no initial deposit?: Set the initial deposit to 0. The calculator works entirely from the monthly contributions.
Can I share a calculation?: Yes. Use the share button to copy a link that reopens the calculator with the same inputs.

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