Financial
Compound Interest Calculator with Contributions
Project compound growth with regular contributions, flexible compounding frequency, and a monthly or yearly balance schedule.
Search intent guide
Use this page when you need a fast answer to compound interest calculator
Use this compound interest calculator when you want to project how a balance grows over time with recurring contributions and compounding frequency changes. It is especially useful for savings plans, investing assumptions, and future-value scenario checks.
Editorial review
Best for
- Projecting long-term growth with monthly contributions
- Testing the difference between contribution timing choices
- Comparing conservative vs optimistic return assumptions
Before you start
- Pick one time horizon before you compare scenarios
- Keep contribution amount and frequency realistic
- Re-run the estimate with a lower return to stress-test the plan
Inputs
See how compounding and monthly contributions build over time.
Results
Totals reflect the selected compounding frequency.
Future value
$31,998.32
Total contributions
$22,000.00
Interest earned
$9,998.32
Balance composition
| Component | Amount |
|---|---|
| Starting balance | $10,000.00 |
| Total contributions | $22,000.00 |
| Interest earned | $9,998.32 |
| Ending balance | $31,998.32 |
Growth schedule
View monthly or yearly balance growth.
| Month | Contribution | Interest | Balance |
|---|---|---|---|
| Mar 2026 | $100.00 | $41.67 | $10,141.67 |
| Apr 2026 | $100.00 | $42.26 | $10,283.92 |
| May 2026 | $100.00 | $42.85 | $10,426.77 |
| Jun 2026 | $100.00 | $43.44 | $10,570.22 |
| Jul 2026 | $100.00 | $44.04 | $10,714.26 |
| Aug 2026 | $100.00 | $44.64 | $10,858.90 |
| Sep 2026 | $100.00 | $45.25 | $11,004.15 |
| Oct 2026 | $100.00 | $45.85 | $11,150.00 |
| Nov 2026 | $100.00 | $46.46 | $11,296.46 |
| Dec 2026 | $100.00 | $47.07 | $11,443.53 |
| Jan 2027 | $100.00 | $47.68 | $11,591.21 |
| Feb 2027 | $100.00 | $48.30 | $11,739.50 |
| Mar 2027 | $100.00 | $48.91 | $11,888.42 |
| Apr 2027 | $100.00 | $49.54 | $12,037.95 |
| May 2027 | $100.00 | $50.16 | $12,188.11 |
| Jun 2027 | $100.00 | $50.78 | $12,338.90 |
| Jul 2027 | $100.00 | $51.41 | $12,490.31 |
| Aug 2027 | $100.00 | $52.04 | $12,642.35 |
| Sep 2027 | $100.00 | $52.68 | $12,795.03 |
| Oct 2027 | $100.00 | $53.31 | $12,948.34 |
| Nov 2027 | $100.00 | $53.95 | $13,102.29 |
| Dec 2027 | $100.00 | $54.59 | $13,256.88 |
| Jan 2028 | $100.00 | $55.24 | $13,412.12 |
| Feb 2028 | $100.00 | $55.88 | $13,568.01 |
| Mar 2028 | $100.00 | $56.53 | $13,724.54 |
| Apr 2028 | $100.00 | $57.19 | $13,881.72 |
| May 2028 | $100.00 | $57.84 | $14,039.56 |
| Jun 2028 | $100.00 | $58.50 | $14,198.06 |
| Jul 2028 | $100.00 | $59.16 | $14,357.22 |
| Aug 2028 | $100.00 | $59.82 | $14,517.04 |
| Sep 2028 | $100.00 | $60.49 | $14,677.53 |
| Oct 2028 | $100.00 | $61.16 | $14,838.69 |
| Nov 2028 | $100.00 | $61.83 | $15,000.52 |
| Dec 2028 | $100.00 | $62.50 | $15,163.02 |
| Jan 2029 | $100.00 | $63.18 | $15,326.20 |
| Feb 2029 | $100.00 | $63.86 | $15,490.06 |
| Mar 2029 | $100.00 | $64.54 | $15,654.60 |
| Apr 2029 | $100.00 | $65.23 | $15,819.83 |
| May 2029 | $100.00 | $65.92 | $15,985.74 |
| Jun 2029 | $100.00 | $66.61 | $16,152.35 |
| Jul 2029 | $100.00 | $67.30 | $16,319.65 |
| Aug 2029 | $100.00 | $68.00 | $16,487.65 |
| Sep 2029 | $100.00 | $68.70 | $16,656.35 |
| Oct 2029 | $100.00 | $69.40 | $16,825.75 |
| Nov 2029 | $100.00 | $70.11 | $16,995.86 |
| Dec 2029 | $100.00 | $70.82 | $17,166.67 |
| Jan 2030 | $100.00 | $71.53 | $17,338.20 |
| Feb 2030 | $100.00 | $72.24 | $17,510.44 |
| Mar 2030 | $100.00 | $72.96 | $17,683.40 |
| Apr 2030 | $100.00 | $73.68 | $17,857.08 |
| May 2030 | $100.00 | $74.40 | $18,031.49 |
| Jun 2030 | $100.00 | $75.13 | $18,206.62 |
| Jul 2030 | $100.00 | $75.86 | $18,382.48 |
| Aug 2030 | $100.00 | $76.59 | $18,559.07 |
| Sep 2030 | $100.00 | $77.33 | $18,736.40 |
| Oct 2030 | $100.00 | $78.07 | $18,914.47 |
| Nov 2030 | $100.00 | $78.81 | $19,093.28 |
| Dec 2030 | $100.00 | $79.56 | $19,272.84 |
| Jan 2031 | $100.00 | $80.30 | $19,453.14 |
| Feb 2031 | $100.00 | $81.05 | $19,634.20 |
| Mar 2031 | $100.00 | $81.81 | $19,816.00 |
| Apr 2031 | $100.00 | $82.57 | $19,998.57 |
| May 2031 | $100.00 | $83.33 | $20,181.90 |
| Jun 2031 | $100.00 | $84.09 | $20,365.99 |
| Jul 2031 | $100.00 | $84.86 | $20,550.85 |
| Aug 2031 | $100.00 | $85.63 | $20,736.48 |
| Sep 2031 | $100.00 | $86.40 | $20,922.88 |
| Oct 2031 | $100.00 | $87.18 | $21,110.06 |
| Nov 2031 | $100.00 | $87.96 | $21,298.02 |
| Dec 2031 | $100.00 | $88.74 | $21,486.76 |
| Jan 2032 | $100.00 | $89.53 | $21,676.29 |
| Feb 2032 | $100.00 | $90.32 | $21,866.60 |
| Mar 2032 | $100.00 | $91.11 | $22,057.71 |
| Apr 2032 | $100.00 | $91.91 | $22,249.62 |
| May 2032 | $100.00 | $92.71 | $22,442.33 |
| Jun 2032 | $100.00 | $93.51 | $22,635.84 |
| Jul 2032 | $100.00 | $94.32 | $22,830.15 |
| Aug 2032 | $100.00 | $95.13 | $23,025.28 |
| Sep 2032 | $100.00 | $95.94 | $23,221.22 |
| Oct 2032 | $100.00 | $96.76 | $23,417.97 |
| Nov 2032 | $100.00 | $97.57 | $23,615.55 |
| Dec 2032 | $100.00 | $98.40 | $23,813.95 |
| Jan 2033 | $100.00 | $99.22 | $24,013.17 |
| Feb 2033 | $100.00 | $100.05 | $24,213.23 |
| Mar 2033 | $100.00 | $100.89 | $24,414.11 |
| Apr 2033 | $100.00 | $101.73 | $24,615.84 |
| May 2033 | $100.00 | $102.57 | $24,818.41 |
| Jun 2033 | $100.00 | $103.41 | $25,021.82 |
| Jul 2033 | $100.00 | $104.26 | $25,226.07 |
| Aug 2033 | $100.00 | $105.11 | $25,431.18 |
| Sep 2033 | $100.00 | $105.96 | $25,637.15 |
| Oct 2033 | $100.00 | $106.82 | $25,843.97 |
| Nov 2033 | $100.00 | $107.68 | $26,051.65 |
| Dec 2033 | $100.00 | $108.55 | $26,260.20 |
| Jan 2034 | $100.00 | $109.42 | $26,469.62 |
| Feb 2034 | $100.00 | $110.29 | $26,679.91 |
| Mar 2034 | $100.00 | $111.17 | $26,891.07 |
| Apr 2034 | $100.00 | $112.05 | $27,103.12 |
| May 2034 | $100.00 | $112.93 | $27,316.05 |
| Jun 2034 | $100.00 | $113.82 | $27,529.86 |
| Jul 2034 | $100.00 | $114.71 | $27,744.57 |
| Aug 2034 | $100.00 | $115.60 | $27,960.18 |
| Sep 2034 | $100.00 | $116.50 | $28,176.68 |
| Oct 2034 | $100.00 | $117.40 | $28,394.08 |
| Nov 2034 | $100.00 | $118.31 | $28,612.39 |
| Dec 2034 | $100.00 | $119.22 | $28,831.61 |
| Jan 2035 | $100.00 | $120.13 | $29,051.74 |
| Feb 2035 | $100.00 | $121.05 | $29,272.79 |
| Mar 2035 | $100.00 | $121.97 | $29,494.76 |
| Apr 2035 | $100.00 | $122.89 | $29,717.65 |
| May 2035 | $100.00 | $123.82 | $29,941.47 |
| Jun 2035 | $100.00 | $124.76 | $30,166.23 |
| Jul 2035 | $100.00 | $125.69 | $30,391.92 |
| Aug 2035 | $100.00 | $126.63 | $30,618.56 |
| Sep 2035 | $100.00 | $127.58 | $30,846.13 |
| Oct 2035 | $100.00 | $128.53 | $31,074.66 |
| Nov 2035 | $100.00 | $129.48 | $31,304.14 |
| Dec 2035 | $100.00 | $130.43 | $31,534.57 |
| Jan 2036 | $100.00 | $131.39 | $31,765.96 |
| Feb 2036 | $100.00 | $132.36 | $31,998.32 |
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How this Compound Interest Calculator works
Projects account growth with flexible compounding, contribution timing, and contribution frequency. Includes a monthly or yearly schedule and start date selection for timeline planning.
Quick guide
Jump to the section you need, then return to the compound interest calculator.
Best use cases
- Project long-term portfolio growth for retirement, college savings, or general investing plans.
- Compare how different monthly contributions change the ending balance over the same horizon.
- Stress-test growth expectations with conservative versus aggressive return assumptions.
Inputs
- Starting balance (principal amount)
- Contribution amount and frequency
- Annual interest rate
- Time horizon in years and months
- Compounding frequency (annual, quarterly, monthly, etc.)
- Contribution timing (start or end of period)
- Start month and year for schedule dates
Outputs
- Future value at the end of the period
- Total contributions (principal + deposits)
- Interest earned above contributions
- Monthly or yearly schedule breakdown
- Total number of compounding periods
Assumptions
- Contributions occur at the end of each month
- Rate is constant and compounded at the selected frequency
- Taxes, fees, and inflation are not included
Common mistakes
- Assuming the projected return is guaranteed even though real investment returns vary over time.
- Using an annual rate that already includes fees, then forgetting to model taxes or inflation separately.
- Comparing scenarios with different contribution timing without noticing the start-versus-end effect.
Tips
- Small rate changes compound significantly over long horizons
- Increase contributions to accelerate growth
- Use conservative rates for planning
Compound Interest Calculator formula guide
Use these compound interest calculator formulas to audit the output or explain it to someone else.
4 formulas
Compound Interest Calculator examples
Review a ready-made compound interest calculator scenario, copy it, then tweak inputs to match your case.
Example
Starter investment
Inputs
- Starting balance 10,000
- Monthly contribution 100
- APR 5% for 10 years
Outputs
- Future value about 29,000
- Interest earned about 7,000
Shows how consistent deposits build over time.
Example
Long horizon plan
Inputs
- Starting balance 5,000
- Monthly contribution 200
- APR 7% for 20 years
Outputs
- Future value about 114,000
- Interest earned about 61,000
Higher rates and longer horizons magnify compounding.
Yearly balance sample (10,000 + 100/mo at 5%)
| Year | Balance | Interest earned |
|---|---|---|
| 1 | 11,300 | 1,300 |
| 5 | 19,000 | 3,000 |
| 10 | 29,000 | 7,000 |
Values are rounded to show growth milestones.
Balance growth by year
Focus point
1
$11,300.00
Position
#1 of 3
Original order
Share of total
19.06%
Total: $59,300.00
Sample based on 10,000 starting balance and 100 monthly.
References
- Compound interest formula
- Future value of an annuity
Learn more
Guides connected to the compound interest calculator
Use these short guides when you want the decision framework behind the numbers, not just the raw output.
Category guide
Financial Calculator Guide
Understand when to use payment, return, tax, and budgeting calculators so you can make cleaner money decisions.
FAQ
Compound Interest Calculator FAQ
What does the Compound Interest Calculator do?
Projects account growth with flexible compounding, contribution timing, and contribution frequency. Includes a monthly or yearly schedule and start date selection for timeline planning. It is part of our financial toolkit.
When should I use this calculator?
Use it when you need to Project long-term portfolio growth for retirement, college savings, or general investing plans. Compare how different monthly contributions change the ending balance over the same horizon.
What inputs do I need?
Typical inputs include Starting balance (principal amount), Contribution amount and frequency, Annual interest rate.
How are the results calculated?
We follow the formulas and assumptions outlined in the "How this calculator works" section. You will see outputs like Future value at the end of the period, Total contributions (principal + deposits), Interest earned above contributions.
What mistakes should I avoid?
Common mistakes include Assuming the projected return is guaranteed even though real investment returns vary over time. Using an annual rate that already includes fees, then forgetting to model taxes or inflation separately.
Can I share or download the results?
Use the Copy link or Print buttons to share your results. If a table or chart appears, you can download the data as CSV.
Is my data stored?
No. Calculations run in your browser and we do not store your inputs.
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