★ COMPARISON · MONEY · SAVINGS
On $10,000 over 5 years, a 4.10% APY high-yield savings account reaches $12,225.13 while a 3.85% APY money market account reaches $12,079.04 — a $146.09 gap from a quarter-point rate difference, compounded. Enter your own deposit, rates, and years below: the calculator runs both accounts side by side and names the winner.
Enter one deposit, both APYs, how many years the money stays put, and any monthly contribution. The calculator grows both accounts with the same model and reports both balances, both gains, and the gap. APY already includes compounding, so the model is balance = principal × (1 + APY)years — no extra compounding step is added on top.
Balance = principal × (1 + APY)years. APY, annual percentage yield, already includes the effect of compounding within the year, so this model does not add a separate compounding frequency: a 4.10% APY means $10,000 becomes $10,410.00 after one year, period. Gain = balance − principal − total monthly contributions. When a monthly contribution is entered, each month's contribution grows at the monthly rate (1 + APY)1/12 − 1, and the contributions accumulate as an ordinary annuity: contribution × ((1 + monthly rate)months − 1) / monthly rate. The model assumes both rates stay fixed for the whole period, no fees, no taxes, no withdrawals, and no minimum-balance penalties.
Setup: $10,000, HYSA 4.10% APY, money market 3.85% APY, 5 years, $0 a month.
Line 1 — the high-yield balance. $10,000 × (1.0410)5 = $12,225.13, a gain of $2,225.13.
Line 2 — the money market balance. $10,000 × (1.0385)5 = $12,079.04, a gain of $2,079.04.
Line 3 — the gap. $12,225.13 − $12,079.04 = $146.09 to the high-yield account. A quarter of a percentage point, compounded for five years, is worth about one and a half percent of the deposit.
A bigger deposit: $25,000, same rates, 5 years. The high-yield account reaches $30,562.84 against the money market account's $30,197.61, a gap of $365.23. The percentage gap is identical; the dollars scale with the deposit.
A short horizon: $10,000 for 1 year. High-yield savings gives $10,410.00 and the money market account $10,385.00 — only $25.00 apart. Over one year the rate gap barely matters; over ten it compounds.
A long horizon: $10,000 for 10 years. High-yield savings reaches $14,945.39 against $14,590.33, a gap of $355.07. Doubling the horizon more than doubles the gap, because each year's extra interest earns interest of its own.
Rates flipped: HYSA 3.85% vs money market 4.10%, $10,000, 5 years. Now the money market account wins: $12,225.13 against $12,079.04, the same $146.09 gap in the other direction. The label never wins; the rate does.
Adding $100 a month: $10,000 plus $100 a month for 5 years. The high-yield account ends at $18,859.22 (contribution growth $6,634.08) and the money market account at $18,672.74 (contribution growth $6,593.70), a gap of $186.48 on $16,000 paid in. Regular contributions widen the gap, because the higher rate applies to every deposit, not just the first one.
The $0 vs $100 a month lesson. With no monthly contribution the 5-year gap is $146.09; with $100 a month it is $186.48. The rate advantage compounds on everything you add, so steady savers benefit more from chasing the higher APY than one-time depositors do.
| Output | Formula | What it means |
|---|---|---|
| High-yield balance | principal × (1 + HYSA APY)years | $12,225.13 at the defaults — what the savings account holds after 5 years. |
| Money market balance | principal × (1 + MMA APY)years | $12,079.04 at the defaults — the same money in the money market account. |
| Gain, each account | balance − principal − contributions | $2,225.13 vs $2,079.04 at the defaults — the interest each account actually earned. |
| The gap | HYSA balance − MMA balance | $146.09 at the defaults — what the higher rate is worth over the chosen horizon. |
| Contribution growth | monthly × ((1 + monthly rate)months − 1) / monthly rate | $6,634.08 vs $6,593.70 with $100 a month for 5 years — growth on the added deposits alone. |
The arithmetic is exact for the inputs, but real accounts move: banks change APYs, often monthly, and the model holds both rates flat. Advertised APYs sometimes apply only above a minimum balance or for a promotional period, and fees, withdrawal limits, and taxes are not modeled — a fee-heavy account can lose a rate advantage quickly. Money market accounts at banks are FDIC-insured like savings accounts, but money market funds sold by brokerages are investments, not deposits, and are not FDIC-insured; confirm which product any quoted rate belongs to. Error policy: negative deposits or contributions, APYs outside 0–30%, and years outside 0–50 are reported as errors rather than modeled.
Bright Side Kit. "HYSA vs Money Market Account Calculator." https://brightoolbox.com/high-yield-savings-vs-money-market/ Accessed October 24, 2026.A high-yield savings account is built for saving; a money market account adds transaction features. Money market accounts often come with checks or a debit card, while savings accounts usually do not. The calculator compares only the money outcome — the features decide the rest.
$2,225.13 in interest, for a $12,225.13 balance. That is $10,000 × (1.0410)5. At 3.85% APY the same deposit reaches $12,079.04, so the quarter-point gap is worth $146.09 over five years.
Not quite: APY already includes compounding. A 4.10% APY means $10,000 becomes $10,410.00 after one year, whatever the bank's internal compounding schedule. Compare APYs to APYs, never an APY to a nominal rate.
Whichever advertises the higher APY. Flip the calculator's rates and the winner flips too: at 3.85% vs 4.10% the money market account wins by the same $146.09. Shop the rate, not the label.
Bank money market accounts are, up to the FDIC limit. Money market funds from a brokerage are investments and are not FDIC-insured, even though the names sound alike. Check which product a rate belongs to before comparing.
No, but it widens the gap. With $100 a month for 5 years the high-yield account ends at $18,859.22 vs $18,672.74, a $186.48 gap instead of $146.09, because the higher rate compounds on every deposit.
Because interest earns interest. The 5-year gap is $146.09; the 10-year gap is $355.07. Each year's extra interest becomes next year's principal, so the gap accelerates with time.
Rate changes, fees, minimums, withdrawal limits, and taxes. Banks move APYs regularly, so treat the result as a comparison at today's rates, not a promise of what either account will pay over the full period.