Compound Interest Calculator
Compare reinvested compound growth with non-reinvested earnings using principal, contributions, annual return, years, and a yearly chart.
| Year | Principal invested | Reinvested | Not reinvested |
|---|---|---|---|
| 1 | $13,600 | $14,195 | $14,183 |
| 2 | $17,200 | $18,605 | $18,545 |
| 3 | $20,800 | $23,241 | $23,088 |
| 4 | $24,400 | $28,113 | $27,810 |
| 5 | $28,000 | $33,235 | $32,713 |
| 6 | $31,600 | $38,619 | $37,795 |
| 7 | $35,200 | $44,279 | $43,058 |
| 8 | $38,800 | $50,228 | $48,500 |
| 9 | $42,400 | $56,481 | $54,122 |
| 10 | $46,000 | $63,055 | $59,925 |
| 11 | $49,600 | $69,964 | $65,907 |
| 12 | $53,200 | $77,228 | $72,070 |
| 13 | $56,800 | $84,862 | $78,413 |
| 14 | $60,400 | $92,888 | $84,935 |
| 15 | $64,000 | $101,324 | $91,638 |
| 16 | $67,600 | $110,191 | $98,520 |
| 17 | $71,200 | $119,513 | $105,583 |
| 18 | $74,800 | $129,311 | $112,825 |
| 19 | $78,400 | $139,610 | $120,247 |
| 20 | $82,000 | $150,437 | $127,850 |
About this tool
Compare reinvested compound growth with non-reinvested earnings using principal, contributions, annual return, years, and a yearly chart.
Your principal, rate, contribution, and time inputs are calculated locally in your browser and are not uploaded to a server.
This is a compound-interest estimate, not investment, financial, tax, or legal advice. Actual results can be higher or lower than the estimate.
How to use it
- Choose how earnings are treated: reinvest, withdraw, or compare both.
- Enter the initial principal.
- Enter a regular contribution and choose monthly, quarterly, or yearly contributions.
- Enter annual return, years, and compounding frequency.
- Review final values, total principal invested, the difference between scenarios, the yearly table, and the growth chart.
Common use cases
- Estimate long-term savings growth
- Compare reinvested earnings with withdrawn earnings
- Compare lump-sum and regular contributions
- Check future value under different annual return assumptions
- Plan education, retirement, or medium-term savings goals
Compound Interest Inputs
Compound interest means interest or returns are added back to the balance, so the next period grows from a larger base. This calculator separates the starting principal, regular contributions, and earnings treatment so the result is easier to read.
| Input | Meaning | Reminder |
|---|---|---|
| Initial principal | The amount already saved or invested at the start. | A larger starting balance gives compounding more base to work with. |
| Regular contribution | A monthly, quarterly, or yearly amount added over time. | This calculator treats contributions as end-of-period deposits. |
| Annual return / rate | The average yearly return or interest assumption. | It is an assumption, not a guaranteed result. |
| Compounding frequency | How often interest is compounded in a year. | More frequent compounding can slightly increase the estimate at the same stated rate. |
| Earnings treatment | Whether earnings are reinvested or withdrawn. | Compare both to see the long-term gap. |
Reinvested Versus Non-Reinvested Earnings
Reinvesting means each period's interest or return goes back into the balance. Non-reinvested earnings are tracked separately, closer to a simple-interest or payout scenario.
The short-term gap may look small, but over longer time horizons the reinvested line can pull away. That is why this calculator includes a yearly comparison chart.
| Mode | How the calculator treats earnings | Useful for |
|---|---|---|
| Reinvest earnings | Each period's earnings are added back to principal. | Long-term compound growth and recurring contribution planning. |
| Withdraw earnings | Each period's earnings are accumulated separately. | Payout, simple-interest, or cash-flow style scenarios. |
| Compare both | Shows reinvested value, non-reinvested value, and principal together. | Understanding the long-term difference from reinvesting. |
Monthly Contribution Example
Suppose you start with $10,000, add $300 per month, assume a 5% annual return, and estimate 20 years with monthly compounding. The calculator shows reinvested value, non-reinvested total value, principal invested, the difference between scenarios, and a yearly projection.
This is useful for planning scenarios, but real returns are not fixed. Fees, taxes, currency changes, inflation, and market volatility can change the actual outcome.
| Step | Example | Why it matters |
|---|---|---|
| Starting balance | $10,000 | The amount already available. |
| Regular contribution | $300 per month | The amount added over time. |
| Annual return | 5% | The long-term average assumption. |
| Yearly chart | Year 1 through year 20 | Shows how principal, reinvested value, and non-reinvested value diverge. |
How to Read the Yearly Chart
The invested principal line is the baseline. The reinvested line shows compound growth. The non-reinvested line shows principal plus accumulated withdrawn earnings.
| Line | Meaning | Reminder |
|---|---|---|
| Principal invested | Initial principal plus all regular contributions. | This is the no-earnings baseline. |
| Reinvested | Estimated balance when earnings keep compounding. | Usually shows the clearest compound effect over time. |
| Not reinvested | Principal plus accumulated withdrawn earnings. | Useful for simple-interest or payout-style comparison. |
What This Calculator Can and Cannot Answer
A compound interest calculator is good for asking what could happen under fixed assumptions. It is not good for deciding whether a specific product will perform well.
| Question | Good fit? | What to do next |
|---|---|---|
| What could a fixed rate produce over 10 years? | Yes | Enter principal, rate, and years. |
| What could monthly contributions grow into? | Yes | Set contribution frequency and amount. |
| How much is a loan payment? | No | Use the loan calculator. |
| Should I buy a specific investment? | No | Review risk, fees, taxes, and personal circumstances separately. |
Avoiding Overconfident Estimates
- Compare conservative, moderate, and optimistic annual return assumptions.
- Consider fees, taxes, currency changes, and inflation outside the calculator.
- For long time horizons, small changes in return assumptions can create large differences.
- For short time horizons, market volatility can matter more than a smooth compound-interest curve.
FAQ
What compound interest formula is used?
The tool simulates each compounding period. Reinvest mode adds each period's earnings back to principal. Withdraw mode tracks those earnings separately instead of adding them back.
Are contributions treated as beginning or end of period?
They are treated as end-of-period contributions. Beginning-of-period contributions would usually produce a slightly higher estimate.
What does withdraw earnings mean?
It means each period's interest or return is taken out and does not earn additional interest. This is closer to a simple-interest or payout scenario.
What does the yearly chart show?
It compares principal invested, reinvested final value, and total value when earnings are not reinvested.
Can I enter a negative return?
Yes. You can enter a negative annual return to model a loss scenario.
Is this an investment recommendation?
No. It is a math estimate and does not recommend any product or guarantee returns.
Are my numbers uploaded?
No. The calculation runs locally in your browser.