Free compound interest calculator
Small steps. Long horizons.
See how compound interest can turn today’s savings into tomorrow’s opportunities.
Live preview. Project growth to confirm your scenario.
Future Value · 10 years
- Total Contributions
- $10,000.00
- Total Interest Earned
- $10,096.61
- Effective Annual Rate
- 7.23%
Monthly contributions earn the equivalent monthly yield. Tax is applied once to positive gains at the end; fees are excluded.
Compare your own assumptions
Keep the same amount and duration while comparing compounding frequency or effective annual yield. These are hypothetical, constant-rate scenarios.
Live preview — select Compare scenarios to confirm. Daily minus monthly: $159.17 over 20 years.
$10,000.00 at 7% nominal annual rate for 20 years
Your frequency comparison
| Final amount | Annual yield | |
|---|---|---|
| Annual | $38,696.84 | 7% |
| Quarterly | $40,063.92 | 7.185903% |
| Monthly | $40,387.39 | 7.229008% |
| Daily | $40,546.56 | 7.250098% |
Same inputs and formula as the chart and export. USD; no cash flows.
Monthly ends at $40,387.39 and daily at $40,546.56. The continuous mathematical limit is $40,552.00; it is not an account offer.
With monthly compounding, the second rate of 5% gives $27,126.40. Main minus second scenario: $13,260.99.
Inspect the formula and year-by-year values
A = P × (1 + r/n)^(n × years). Rates in the formula are decimals. Daily uses n = 365. Continuous limit: P × exp(r × years). Fixed-rate examples do not predict investment performance.
| Year | Monthly | Daily | Second rate |
|---|---|---|---|
| 0 | $10,000.00 | $10,000.00 | $10,000.00 |
| 1 | $10,722.90 | $10,725.01 | $10,511.62 |
| 2 | $11,498.06 | $11,502.58 | $11,049.41 |
| 3 | $12,329.26 | $12,336.53 | $11,614.72 |
| 4 | $13,220.54 | $13,230.94 | $12,208.95 |
| 5 | $14,176.25 | $14,190.20 | $12,833.59 |
| 6 | $15,201.06 | $15,219.00 | $13,490.18 |
| 7 | $16,299.94 | $16,322.40 | $14,180.36 |
| 8 | $17,478.26 | $17,505.79 | $14,905.85 |
| 9 | $18,741.77 | $18,774.97 | $15,668.47 |
| 10 | $20,096.61 | $20,136.18 | $16,470.09 |
| 11 | $21,549.40 | $21,596.07 | $17,312.74 |
| 12 | $23,107.21 | $23,161.80 | $18,198.49 |
| 13 | $24,777.63 | $24,841.06 | $19,129.56 |
| 14 | $26,568.81 | $26,642.06 | $20,108.26 |
| 15 | $28,489.47 | $28,573.63 | $21,137.04 |
| 16 | $30,548.97 | $30,645.25 | $22,218.45 |
| 17 | $32,757.36 | $32,867.06 | $23,355.19 |
| 18 | $35,125.39 | $35,249.96 | $24,550.08 |
| 19 | $37,664.61 | $37,805.61 | $25,806.11 |
| 20 | $40,387.39 | $40,546.56 | $27,126.40 |
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CalcMyCompound
AI assistant · Project growth
Ask about compounding, rates, contributions or savings goals. Educational scenarios, not forecasts or investment advice.
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest — which is calculated only on your original deposit — compound interest lets your money earn interest on its interest, creating an exponential growth curve over time.
How to use CalcMyCompound
- 1
Initial Investment (Principal) — P = Initial Investment (Principal)
- 2
Monthly Contribution — Monthly contributions earn the equivalent monthly yield. Tax is applied once to positive gains at the end; fees are excluded.
- 3
Annual Interest Rate (%) — Illustrative assumptions. Rates are constant; results are not a forecast.
- 4
Compounding Frequency — Daily (365/year), Monthly (12/year), Quarterly (4/year), Annually (1/year)
- 5
Investment Period — Project growth
What Is Compound Interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest — which is calculated only on your original deposit — compound interest lets your money earn interest on its interest, creating an exponential growth curve over time.
Formula
A = P(1 + r/n)^(nt)A · P · r · n · t
- A = Future Value
- P = Initial Investment (Principal)
- r = Annual Interest Rate (%) ÷ 100
- n = Compounding Frequency
- t = Investment Period (years)
Quick Examples
Initial Investment (Principal): 10,000 USD · Annual Interest Rate (%): 7% · Investment Period: 10 · Monthly (12/year) → 20,096.61 USD. Illustrative assumptions. Rates are constant; results are not a forecast.
Simple Interest Calculator / Free compound interest calculator
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest — which is calculated only on your original deposit — compound interest lets your money earn interest on its interest, creating an exponential growth curve over time.
Investment Period: 20 · Annual Interest Rate (%): 7% · Initial Investment (Principal): 10,000 USD. Simple Interest Calculator: 24,000 USD; Free compound interest calculator: 38,696.84 USD.
Read more → What Is Compound Interest?
72 ÷ Annual Interest Rate (%)
Dividing 72 by a positive annual rate gives an approximate doubling time in years. This is a shortcut, not an exact calculation or a forecast.
72 ÷ Annual Interest Rate (%)72 ÷ 8 ≈ 9 years
Read more → The Rule of 72: An Approximation, with Exact Comparisons
Quick Examples
Illustrative assumptions. Rates are constant; results are not a forecast.
Initial Investment (Principal): 10,000 USD · Annual Interest Rate (%): 7% · Investment Period: 10 · Monthly (12/year)
- 1Formula:
A = P(1 + r/n)^(nt) - 2Future Value:
10,000 × (1 + 0.07 / 12)^(12 × 10) ≈ 20,096.61 USD
Monthly contributions earn the equivalent monthly yield. Tax is applied once to positive gains at the end; fees are excluded.
Frequently Asked Questions
How are monthly contributions and tax calculated?
Monthly contributions earn the equivalent monthly yield. Tax is applied once to positive gains at the end; fees are excluded.
Are these returns guaranteed?
Illustrative assumptions. Rates are constant; results are not a forecast.
Which input values are supported?
Enter valid amounts. Rate: greater than −100% to 100%; inflation and tax: 0–100%.