Savings Calculator
Project your savings growth over time. See how regular deposits and compound interest add up.
Saving $200 a month from a $5,000 starting balance at 4% interest grows to $36,904 in ten years, of which $7,904 is interest and $29,000 is money you contributed.
Calculator
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How This Calculator Works
Savings growth combines your starting amount and regular deposits with compound interest:
FV = Start × (1+r)^n + PMT × [(1+r)^n - 1] / r
Worked example
Using the calculator defaults — $5,000 starting balance, 4% annual interest, 10 years, and $200 added at the end of each month:
With monthly compounding, r = 4% ÷ 12 = 0.003333 and n = 120 months.
Grow the starting balance. $5,000 × (1.003333)^120 = $7,453. Your original $5,000 earned $2,453 on its own.
Grow the monthly contributions. The annuity factor is ((1.003333)^120 − 1) ÷ 0.003333 = 147.23. Multiply by the $200 monthly contribution: $29,446.
Add the two together. $7,453 + $29,446 = $36,899 — the balance at the end of year ten. The calculator rounds this to $36,904 because it compounds every month rather than in one step.
Separate what you put in from what you earned. You contributed $5,000 + (200 × 120) = $29,000. The balance is $36,904, so $7,904 is interest — 21% of the final balance came from returns, not from saving harder.
Enter 5000, 4, 10 and 200 in the calculator above to confirm the $36,904 figure. Contributions are assumed to arrive at the end of each month, which is the conservative convention.
What each variable is worth over 10 years
All rows start from $5,000 with monthly compounding and contributions at the end of each month. Each row changes one variable.
| Scenario | Final balance | Total contributed | Interest earned |
|---|---|---|---|
| $200/mo at 4%, 10 years (baseline) | $36,904 | $29,000 | $7,904 |
| $400/mo at 4%, 10 years | $66,354 | $53,000 | $13,354 |
| $200/mo at 7%, 10 years | $44,665 | $29,000 | $15,665 |
| $200/mo at 1%, 10 years | $30,756 | $29,000 | $1,756 |
| $200/mo at 4%, 20 years | $84,468 | $53,000 | $31,468 |
Doubling your monthly saving adds $29,450 to the ten-year balance. Raising the return from 4% to 7% adds $7,761. Over a decade the amount you save matters more than the rate; extend the horizon and the rate takes over.
Common mistakes with this calculation
- Comparing a compound rate with a simple rate. A 4% APY already includes the effect of compounding within the year, while a 4% nominal rate compounded monthly is an effective 4.074%. Comparing the two directly overstates one of them. Use APY for savings accounts and check what the account actually quotes.
- Assuming the rate stays fixed for the whole term. Savings rates move with central-bank policy. A 4% rate available today may be 1.5% in three years. The calculator holds the rate constant because that is the only way to show a clean result, not because it is realistic.
- Forgetting tax on interest. Interest in a taxable account is taxed as ordinary income each year, even if you leave it in the account. At a 22% marginal rate a 4% return delivers roughly 3.1% after tax. Use a tax-advantaged account and the gross figure is closer to the truth.
- Saving in a fixed order instead of automating it. Savings that depend on what is left at the end of the month tend to be small and irregular. An automatic transfer on payday is the single change that most reliably moves real balances toward the modelled figure.
When this calculator does not apply
- The rate is held constant for the entire term. No savings product guarantees a rate for ten years.
- Contributions are assumed to arrive at a regular interval with no gaps, no withdrawals and no missed months.
- Tax is not modelled. At a 22% marginal rate, interest in a taxable account is worth roughly a fifth less than shown.
- Inflation is not modelled. At 3% inflation, $36,973 in ten years buys what about $27,500 buys today.
- Deposit insurance caps apply per depositor, per institution. Balances above the limit carry bank risk that the calculator does not represent.
Frequently Asked Questions
Where can I earn 4% on savings?
High-yield savings accounts and money market accounts at online banks often offer 3-5% APY. Traditional banks typically offer 0.01-0.5%.
Should I save or invest?
For short-term goals (< 5 years), savings accounts are safer. For long-term goals (10+ years), investing typically offers higher returns but with more risk.
Sources & Methodology
This calculator uses standard financial formulas. See our methodology page for the full formula derivation.
- Your Insured Deposits Federal Deposit Insurance Corporation
- National Rates and Rate Caps Federal Deposit Insurance Corporation
- Share Insurance Fund Overview National Credit Union Administration
- Consumer Information on Saving Consumer Financial Protection Bureau
- Interest Rates and APY Explained Federal Reserve
Last reviewed .
Key takeaways
- $5,000 plus $200 a month at 4% reaches $36,973 in ten years — of which $7,973 is interest.
- Over a decade, the amount you contribute dominates the result. Over three decades, the rate dominates.
- Always compare APY to APY. A nominal rate compounded monthly is not the same number as an APY.
- Interest in a taxable account is taxed every year. A tax-advantaged account keeps the full compounding effect.
- Automate the transfer. The modelled result assumes every payment is made, on time, without exception.