★ MONEY · SAVINGS · MONEY MARKET
$25,469.76 in 5 years — $3,469.76 of it interest. A $10,000 deposit at 4% APY compounded monthly, with $200 added each month, grows to $25,469.76. The APY is a nominal rate compounded monthly, so the effective yield is 4.07%. Enter your deposit to work out yours.
A money market account pays interest on the balance, and the interest is added to the balance each month. This calculator works out the future value, the interest earned, the effective annual yield, and what the final month earns — with the deposit, the APY, the monthly contribution, and the years you choose.
A money market account pays interest on the balance, and the interest is added to the balance each month, so the next month earns interest on the interest. The APY is treated here as a nominal rate compounded monthly: the monthly rate is the APY divided by 12, and the future value is the deposit grown by the monthly rate for n months, plus each monthly contribution grown for the months that are left. The total contributions are the deposit plus 12 times the years times the monthly contribution, and the interest is the future value minus the contributions. The effective annual yield is (1 + the monthly rate) to the power of 12, minus 1 — a little more than the APY itself, because the monthly compounding adds a month of interest on the interest. The final-month interest is the balance at the start of the last month times the monthly rate.
At the defaults — a $10,000 deposit, 4% APY compounded monthly, $200 a month, 5 years (60 months) — the monthly rate is 4% ÷ 12 = 0.3333%, and the future value is $10,000 × 1.00333360 + $200 × (1.00333360 − 1) ÷ 0.003333 = $25,469.76. The contributions are $10,000 + 60 × $200 = $22,000.00, so the interest is $25,469.76 − $22,000.00 = $3,469.76. The effective annual yield is 1.00333312 − 1 = 4.07% (exact 4.0742%), and the final month earns $83.95 of interest.
| Case | Future value | Interest | Contributions | Effective yield |
|---|---|---|---|---|
| Default ($10,000, 4%, $200/mo, 5 years) | $25,469.76 | $3,469.76 | $22,000.00 | 4.07% |
| $5,000 deposit | $19,364.78 | $2,364.78 | $17,000.00 | 4.07% |
| $25,000 deposit | $43,784.71 | $6,784.71 | $37,000.00 | 4.07% |
| 2% APY | $23,660.26 | $1,660.26 | $22,000.00 | 2.02% |
| 5.5% APY | $26,933.20 | $4,933.20 | $22,000.00 | 5.64% |
| No monthly contribution | $12,209.97 | $2,209.97 | $10,000.00 | 4.07% |
| $500 a month | $45,359.46 | $5,359.46 | $40,000.00 | 4.07% |
| 1 year | $12,851.91 | $451.91 | $12,400.00 | 4.07% |
| 10 years | $44,358.29 | $10,358.29 | $34,000.00 | 4.07% |
| 20 years | $95,580.75 | $37,580.75 | $58,000.00 | 4.07% |
| 30 years | $171,944.86 | $89,944.86 | $82,000.00 | 4.07% |
Setup: deposit $10,000, APY 4% compounded monthly, monthly contribution $200, years 5 (60 months).
Line 1 — the monthly rate. 4% ÷ 12 = 0.3333% a month (0.003333 as a decimal).
Line 2 — the deposit grown. $10,000 × 1.00333360 = $12,209.97 — the deposit alone, with no contributions, in 5 years.
Line 3 — the contributions grown. $200 × (1.00333360 − 1) ÷ 0.003333 = $13,259.80 — the $200 a month alone, with no starting deposit.
Line 4 — the future value. $12,209.97 + $13,259.80 = $25,469.76.
Line 5 — the interest. $25,469.76 − $22,000.00 = $3,469.76, on $22,000.00 put in.
Line 6 — the effective yield. 1.00333312 − 1 = 4.07% (exact 4.0742%) a year, and the final month earns $83.95 of interest.
Reverse: to reach $50,000 the APY would need to be 21.37% (exact 21.3731); at 4% APY it would take 11.32 years (exact 11.3185); the deposit needed is $30,090.34 (exact 30,090.3414); and the monthly contribution needed is $569.99 (exact 569.9942).
$5,000 deposit: the future value is $19,364.78 and the interest is $2,364.78 on $17,000.00 put in. Halving the deposit cuts the future value by $6,104.98, not by half, because the contributions stay the same.
$25,000 deposit: the future value is $43,784.71 and the interest is $6,784.71 on $37,000.00 put in. A bigger deposit earns more interest in the same 5 years.
2% APY: the future value is $23,660.26 and the interest is $1,660.26, with an effective yield of 2.02%. Halving the rate more than halves the interest, because the compounding has less to work with.
5.5% APY: the future value is $26,933.20 and the interest is $4,933.20, with an effective yield of 5.64%. A point and a half more APY adds $1,463.44 to the future value.
No monthly contribution: the future value is $12,209.97 and the interest is $2,209.97 on $10,000.00 put in. The deposit alone is the same $12,209.97 as Line 2 of the worked example.
$500 a month: the future value is $45,359.46 and the interest is $5,359.46 on $40,000.00 put in. The contributions do most of the work: $30,000.00 of the $40,000.00 is the extra $300 a month.
1 year: the future value is $12,851.91 and the interest is $451.91 on $12,400.00 put in. In the first year the interest is small, because the balance has had little time to compound.
10 years: the future value is $44,358.29 and the interest is $10,358.29 on $34,000.00 put in. Doubling the time from 5 to 10 years nearly triples the interest.
20 years: the future value is $95,580.75 and the interest is $37,580.75 on $58,000.00 put in. By year 20 the interest is more than half of what was put in.
30 years: the future value is $171,944.86 and the interest is $89,944.86 on $82,000.00 put in. Over 30 years the interest is more than the deposit and the contributions combined would have been without it.
Reverse — the other way round: to reach $50,000 the APY would need to be 21.37%; at 4% APY it would take 11.32 years; the deposit needed is $30,090.34; and the monthly contribution needed is $569.99.
The model assumes the APY stays the same for the whole term, the monthly contribution is added at the end of each month, and no money is taken out. It assumes the APY is a nominal rate compounded monthly, and it shows the effective annual yield alongside it so the two are never confused. It assumes no fees, no taxes on the interest, and no minimum-balance rules — check the account terms, because money market accounts often need a minimum balance and limit withdrawals. It leaves out inflation: $25,469.76 in 5 years buys less than $25,469.76 today. With a 0% APY the future value is exactly what you put in, $22,000.00, and the interest is $0.00. With 0 years the future value is the deposit itself, $10,000.00. Rounding convention: money is rounded to cents, percents to two decimals, the effective yield and the reverses to two decimals with the exact value to four, and all figures are computed from unrounded values, rounded only for display.
| Output | Formula | What it means |
|---|---|---|
| Future value | deposit × (1 + i)n + contribution × ((1 + i)n − 1) ÷ i | $25,469.76. |
| Total contributions | deposit + 12 × years × monthly contribution | $22,000.00. |
| Interest earned | future value − total contributions | $3,469.76. |
| Effective annual yield | (1 + i)12 − 1, where i is the monthly rate | 4.07% (exact 4.0742). |
| Final-month interest | balance at month n − 1 × the monthly rate | $83.95. |
| APY needed for $50,000 | the APY that grows the same deposit and contribution to $50,000 | 21.37% (exact 21.3731). |
| Years to reach $50,000 | the years that grow the same deposit and contribution to $50,000 at 4% APY | 11.32 (exact 11.3185). |
| Deposit needed for $50,000 | ($50,000 − the contribution part) ÷ (1 + i)n | $30,090.34 (exact 30,090.3414). |
| Monthly contribution needed for $50,000 | ($50,000 − deposit × (1 + i)n) ÷ ((1 + i)n − 1) × i | $569.99 (exact 569.9942). |
| $0 deposit | same model, no starting deposit | Future value $13,259.80, interest $1,259.80. |
| No contribution (edge) | same model, $0 a month | Future value $12,209.97, interest $2,209.97. |
| 0 years | same model, 0 years | Future value $10,000.00 — the deposit itself. |
| 0% APY | same model, no interest | Future value $22,000.00, interest $0.00. |
| $5,000 deposit | same model, $5,000 deposit | Future value $19,364.78, interest $2,364.78, contributions $17,000.00. |
| $25,000 deposit | same model, $25,000 deposit | Future value $43,784.71, interest $6,784.71, contributions $37,000.00. |
| 2% APY | same model, 2% APY | Future value $23,660.26, interest $1,660.26, contributions $22,000.00. |
| 5.5% APY | same model, 5.5% APY | Future value $26,933.20, interest $4,933.20, contributions $22,000.00. |
| No monthly contribution | same model, $0 a month | Future value $12,209.97, interest $2,209.97, contributions $10,000.00. |
| $500 a month | same model, $500 a month | Future value $45,359.46, interest $5,359.46, contributions $40,000.00. |
| 1 year | same model, 1 year | Future value $12,851.91, interest $451.91, contributions $12,400.00. |
| 10 years | same model, 10 years | Future value $44,358.29, interest $10,358.29, contributions $34,000.00. |
| 20 years | same model, 20 years | Future value $95,580.75, interest $37,580.75, contributions $58,000.00. |
| 30 years | same model, 30 years | Future value $171,944.86, interest $89,944.86, contributions $82,000.00. |
The math is exact for the numbers you enter: the monthly rate is the APY divided by 12, the future value is the deposit and the contributions grown month by month, and the interest is the future value minus what was put in. What the model cannot do is know the future rate: check the APY, because money market rates move with the market and the rate you see today is not the rate you will earn in 5 years. It assumes the APY is a nominal rate compounded monthly and shows the effective yield alongside it, and it assumes the contribution is added at the end of each month with no withdrawals, no fees, and no taxes. It leaves out inflation and any minimum-balance or withdrawal limits. For how compounding grows any deposit, see compound growth calculator; for how much to save each month to hit a target, see savings goal calculator.
Bright Side Kit. "Money Market Account Calculator: Interest & Growth 2026." https://brightoolbox.com/money-market-account-calculator/ Accessed October 25, 2026.$3,469.76, on top of $22,000.00 put in. A $10,000 deposit at 4% APY compounded monthly, with $200 added each month for 5 years, grows to $25,469.76. The contributions are $10,000 plus 60 months of $200, which is $22,000.00, so the interest is $25,469.76 minus $22,000.00, which is $3,469.76. The effective annual yield is 4.07%, and the final month earns $83.95 of interest.
Almost — the APY is a nominal rate compounded monthly, so the effective yield is a little higher. A 4% APY compounded monthly pays a monthly rate of 4% divided by 12, which is 0.3333% a month, and over a year that compounds to an effective yield of 4.07% (exact 4.0742%). At 2% APY the effective yield is 2.02%, and at 5.5% APY it is 5.64%. The difference is small at these rates, but it grows with the rate.
The $10,000 alone grows to $12,209.97 in 5 years. With no monthly contribution the interest is $2,209.97, against $3,469.76 with $200 a month. The contributions are the bigger lever here: $200 a month for 5 years is $12,000.00 of the $22,000.00 put in, and it adds $1,259.79 of interest on top of the deposit alone. At $500 a month the future value is $45,359.46, with $5,359.46 of interest on $40,000.00 put in.
11.32 years at 4% APY with the same $200 a month. The exact answer is 11.3185 years. With a bigger deposit the wait shortens: a $25,000 deposit reaches $43,784.71 in 5 years, and a $30,090.34 deposit reaches $50,000.00 in 5 years at the same 4% APY and $200 a month. Or raise the monthly contribution to $569.99 a month, which also reaches $50,000.00 in 5 years.
21.37% — far above any money market rate. The exact APY is 21.3731%. That is the point: a money market account is for safe, liquid savings, not for doubling money in 5 years. At a realistic 5.5% APY the same $10,000 and $200 a month reaches only $26,933.20 in 5 years. If $50,000 in 5 years is the goal, the deposit or the monthly contribution has to do the work, not the rate.
The future value is exactly what you put in: $22,000.00. With a 0% APY there is no interest, so the $10,000 deposit plus 60 months of $200 is $22,000.00, and the interest is $0.00. With 0 years the future value is the deposit itself, $10,000.00. And with a $0 deposit the $200 a month alone grows to $13,259.80 in 5 years, with $1,259.80 of interest.