Compound interest calculator.
Use this free compound interest calculator to watch a balance grow over time — with any compounding frequency, optional regular deposits, the effective APY, and a year-by-year deposits-vs-interest breakdown.
Use the Personal Loan Calculator.
Results update automatically as you type. No account is required.
Enter your savings details
Starting balance
The principal you begin with and the annual interest rate it earns.
Compounding & time
How often interest is added, and how long the money grows.
Regular deposits (optional)
Add money on a schedule to see contributions stack alongside interest. Leave at 0 for pure compound growth.
A $10,000 deposit at 5% compounded monthly for 10y grows to $16,470 — $10,000 deposited and $6,470 earned in interest (APY 5.12%).
Amortization schedule
Every payment split into principal and interest, with your balance falling to zero. Switch between the month-by-month view and a yearly summary.
| Month | Deposit | Interest | Balance |
|---|---|---|---|
| 1 | $0.00 | $41.67 | $10,041.67 |
| 2 | $0.00 | $41.84 | $10,083.51 |
| 3 | $0.00 | $42.01 | $10,125.52 |
| 4 | $0.00 | $42.19 | $10,167.71 |
| 5 | $0.00 | $42.37 | $10,210.08 |
| 6 | $0.00 | $42.54 | $10,252.62 |
| 7 | $0.00 | $42.72 | $10,295.34 |
| 8 | $0.00 | $42.90 | $10,338.24 |
| 9 | $0.00 | $43.08 | $10,381.31 |
| 10 | $0.00 | $43.26 | $10,424.57 |
| 11 | $0.00 | $43.44 | $10,468.00 |
| 12 | $0.00 | $43.62 | $10,511.62 |
| 13 | $0.00 | $43.80 | $10,555.42 |
| 14 | $0.00 | $43.98 | $10,599.40 |
| 15 | $0.00 | $44.16 | $10,643.56 |
| 16 | $0.00 | $44.35 | $10,687.91 |
| 17 | $0.00 | $44.53 | $10,732.44 |
| 18 | $0.00 | $44.72 | $10,777.16 |
| 19 | $0.00 | $44.90 | $10,822.07 |
| 20 | $0.00 | $45.09 | $10,867.16 |
| 21 | $0.00 | $45.28 | $10,912.44 |
| 22 | $0.00 | $45.47 | $10,957.91 |
| 23 | $0.00 | $45.66 | $11,003.57 |
| 24 | $0.00 | $45.85 | $11,049.41 |
| 25 | $0.00 | $46.04 | $11,095.45 |
| 26 | $0.00 | $46.23 | $11,141.68 |
| 27 | $0.00 | $46.42 | $11,188.11 |
| 28 | $0.00 | $46.62 | $11,234.72 |
| 29 | $0.00 | $46.81 | $11,281.54 |
| 30 | $0.00 | $47.01 | $11,328.54 |
| 31 | $0.00 | $47.20 | $11,375.74 |
| 32 | $0.00 | $47.40 | $11,423.14 |
| 33 | $0.00 | $47.60 | $11,470.74 |
| 34 | $0.00 | $47.79 | $11,518.53 |
| 35 | $0.00 | $47.99 | $11,566.53 |
| 36 | $0.00 | $48.19 | $11,614.72 |
| 37 | $0.00 | $48.39 | $11,663.12 |
| 38 | $0.00 | $48.60 | $11,711.71 |
| 39 | $0.00 | $48.80 | $11,760.51 |
| 40 | $0.00 | $49.00 | $11,809.51 |
| 41 | $0.00 | $49.21 | $11,858.72 |
| 42 | $0.00 | $49.41 | $11,908.13 |
| 43 | $0.00 | $49.62 | $11,957.75 |
| 44 | $0.00 | $49.82 | $12,007.57 |
| 45 | $0.00 | $50.03 | $12,057.60 |
| 46 | $0.00 | $50.24 | $12,107.84 |
| 47 | $0.00 | $50.45 | $12,158.29 |
| 48 | $0.00 | $50.66 | $12,208.95 |
| 49 | $0.00 | $50.87 | $12,259.82 |
| 50 | $0.00 | $51.08 | $12,310.91 |
| 51 | $0.00 | $51.30 | $12,362.20 |
| 52 | $0.00 | $51.51 | $12,413.71 |
| 53 | $0.00 | $51.72 | $12,465.44 |
| 54 | $0.00 | $51.94 | $12,517.37 |
| 55 | $0.00 | $52.16 | $12,569.53 |
| 56 | $0.00 | $52.37 | $12,621.90 |
| 57 | $0.00 | $52.59 | $12,674.49 |
| 58 | $0.00 | $52.81 | $12,727.30 |
| 59 | $0.00 | $53.03 | $12,780.34 |
| 60 | $0.00 | $53.25 | $12,833.59 |
| 61 | $0.00 | $53.47 | $12,887.06 |
| 62 | $0.00 | $53.70 | $12,940.76 |
| 63 | $0.00 | $53.92 | $12,994.68 |
| 64 | $0.00 | $54.14 | $13,048.82 |
| 65 | $0.00 | $54.37 | $13,103.19 |
| 66 | $0.00 | $54.60 | $13,157.79 |
| 67 | $0.00 | $54.82 | $13,212.61 |
| 68 | $0.00 | $55.05 | $13,267.66 |
| 69 | $0.00 | $55.28 | $13,322.95 |
| 70 | $0.00 | $55.51 | $13,378.46 |
| 71 | $0.00 | $55.74 | $13,434.20 |
| 72 | $0.00 | $55.98 | $13,490.18 |
| 73 | $0.00 | $56.21 | $13,546.39 |
| 74 | $0.00 | $56.44 | $13,602.83 |
| 75 | $0.00 | $56.68 | $13,659.51 |
| 76 | $0.00 | $56.91 | $13,716.42 |
| 77 | $0.00 | $57.15 | $13,773.57 |
| 78 | $0.00 | $57.39 | $13,830.96 |
| 79 | $0.00 | $57.63 | $13,888.59 |
| 80 | $0.00 | $57.87 | $13,946.46 |
| 81 | $0.00 | $58.11 | $14,004.57 |
| 82 | $0.00 | $58.35 | $14,062.93 |
| 83 | $0.00 | $58.60 | $14,121.52 |
| 84 | $0.00 | $58.84 | $14,180.36 |
| 85 | $0.00 | $59.08 | $14,239.45 |
| 86 | $0.00 | $59.33 | $14,298.78 |
| 87 | $0.00 | $59.58 | $14,358.35 |
| 88 | $0.00 | $59.83 | $14,418.18 |
| 89 | $0.00 | $60.08 | $14,478.26 |
| 90 | $0.00 | $60.33 | $14,538.58 |
| 91 | $0.00 | $60.58 | $14,599.16 |
| 92 | $0.00 | $60.83 | $14,659.99 |
| 93 | $0.00 | $61.08 | $14,721.07 |
| 94 | $0.00 | $61.34 | $14,782.41 |
| 95 | $0.00 | $61.59 | $14,844.00 |
| 96 | $0.00 | $61.85 | $14,905.85 |
| 97 | $0.00 | $62.11 | $14,967.96 |
| 98 | $0.00 | $62.37 | $15,030.33 |
| 99 | $0.00 | $62.63 | $15,092.96 |
| 100 | $0.00 | $62.89 | $15,155.84 |
| 101 | $0.00 | $63.15 | $15,218.99 |
| 102 | $0.00 | $63.41 | $15,282.40 |
| 103 | $0.00 | $63.68 | $15,346.08 |
| 104 | $0.00 | $63.94 | $15,410.02 |
| 105 | $0.00 | $64.21 | $15,474.23 |
| 106 | $0.00 | $64.48 | $15,538.71 |
| 107 | $0.00 | $64.74 | $15,603.45 |
| 108 | $0.00 | $65.01 | $15,668.47 |
| 109 | $0.00 | $65.29 | $15,733.75 |
| 110 | $0.00 | $65.56 | $15,799.31 |
| 111 | $0.00 | $65.83 | $15,865.14 |
| 112 | $0.00 | $66.10 | $15,931.24 |
| 113 | $0.00 | $66.38 | $15,997.62 |
| 114 | $0.00 | $66.66 | $16,064.28 |
| 115 | $0.00 | $66.93 | $16,131.22 |
| 116 | $0.00 | $67.21 | $16,198.43 |
| 117 | $0.00 | $67.49 | $16,265.92 |
| 118 | $0.00 | $67.77 | $16,333.70 |
| 119 | $0.00 | $68.06 | $16,401.75 |
| 120 | $0.00 | $68.34 | $16,470.09 |
About the Compound Interest Calculator
Compound interest is interest earned on both your original money and the interest already added — “interest on interest.” This calculator shows how a starting balance, plus any regular deposits, grows over time at the compounding frequency you choose. You get the end balance, the interest earned, the effective annual yield (APY), a year-by-year chart of deposits versus interest, and a full schedule.
How compounding works
Each period, interest is calculated on the current balance and added back, so the next period earns interest on a slightly larger amount. The more often interest compounds — annually, monthly, daily, or continuously — the faster it grows, because earnings start earning sooner. The growth chart makes this visible: the blue (deposited) portion stays steady while the green (interest) portion accelerates in later years.
Nominal rate vs. APY
The nominal rate is the stated annual rate. The effective annual yield (APY) is what you actually earn once compounding is included — always equal to or higher than the nominal rate. For example, 5% compounded monthly produces an APY of about 5.12%. APY is the fair way to compare savings accounts, CDs, and bonds that compound on different schedules.
The power of time and regular deposits
Time is compound interest’s biggest lever — the longer money stays invested, the larger the interest share becomes. Adding regular deposits accelerates this further: each deposit starts its own compounding journey. Try raising the time horizon or adding a small monthly deposit to see how dramatically the end balance changes.
Important disclaimer
⚠ Disclaimer: This compound interest calculator is for general education and planning only and is not financial advice. It assumes a constant rate and regular compounding, and does not account for taxes, fees, or inflation unless you adjust the rate. Real savings and investment returns vary and may be lower. Verify account terms with your bank or provider.
Related calculators
Investment Calculator · 401(k) Calculator · Roth IRA Calculator · Amortization Calculator
Compound Interest Calculator FAQ
What is compound interest?
It is interest earned on both your original principal and the interest already accumulated. Over time this “interest on interest” effect makes a balance grow faster than simple interest, which is paid only on the principal.
How does compounding frequency affect growth?
More frequent compounding produces a slightly higher balance at the same nominal rate, because interest is added and starts earning sooner. Daily and continuous compounding give the most; annual gives the least.
What is APY and how is it different from the interest rate?
APY (annual percentage yield) is the effective yearly return once compounding is included. It is equal to or higher than the nominal rate and is the best figure for comparing accounts that compound on different schedules.
Can I include regular deposits?
Yes. Enter a deposit amount and choose monthly or annual. Each deposit begins compounding from when it is added, so regular saving can dwarf the starting balance over long periods.
How is the end balance calculated?
The calculator grows the balance period by period: it adds each period’s interest, then any deposit, and repeats to the end of the term, totalling what you deposited and the interest earned on top.
Does this account for taxes or inflation?
No. To approximate them, lower the rate — for instance subtract your expected inflation rate to see the result in today’s purchasing power.
Is this compound interest calculator free?
Yes. It is free, requires no sign-up, and runs entirely in your browser.