Investing
Compound interest and SIP calculator
Project lump-sum and monthly investment growth with compound interest. Include rising contributions, inflation and the first-million milestone.
Content updated . Assumptions reviewed .
Your inputs
Showing the example. Edit your inputs, then calculate.
Projected value
10,000 USD
Projected balance from your assumed return and beginning-of-month contributions.
- Contributed
- 10,000
- Interest
- 0
- Real Value
- 10,000
- First Million Month
- Not reached
- First Million Date
- Not reached
Illustrative result from your inputs and the dated assumptions shown; not a forecast, recommendation or offer
KlarFort is not financial, investment, tax, or legal advice. Verify outputs before making material decisions. Read the disclaimer.
Personal and commercial use is free with credit to KlarFort. See usage and credit.
About this calculator
Explore how a starting balance and regular monthly contributions grow under a constant return assumption. SIP means systematic investment plan, modeled here as contributions at the beginning of each month.
You can grow the contribution amount over time, compare the ending balance with its inflation-adjusted value and check whether the projection reaches one million units of the selected currency.
How to use this calculator
- Enter the starting balance, projection length in months and assumed effective annual return.
- Choose SIP for monthly contributions or lump sum for the starting balance alone.
- For SIP, enter the monthly contribution and its annual growth rate. Add inflation and a starting month.
- Calculate to compare the ending balance, total contributed, modeled gains and value in today's money.
Understand your result
Projected value includes the starting balance, contributions and modeled growth. Real value adjusts the ending balance for the inflation rate you entered; it is expressed in starting-period purchasing power.
The first-million milestone appears only if the balance reaches 1,000,000 in the selected currency within the projection. It is a numerical milestone, not a currency conversion or a forecast.
Questions about this calculator
When are monthly contributions invested?
Contributions enter at the beginning of each month and earn that month's modeled return. Annual contribution growth is converted to a monthly factor, so increases occur gradually each month.
Does lump-sum mode include the monthly contribution?
No. Lump-sum mode uses only the starting balance and assumed return. Select SIP when you want regular monthly saving included.
Are investment fees and taxes included?
This calculator shows growth and an inflation adjustment without fees or tax deductions. The investment growth calculator provides separate fee, tax, withdrawal and simulation inputs.
Where do my figures go?
Your page calculations run in this browser. The API and connected assistants send the inputs supplied to them to our Cloudflare Worker. See Privacy.
How can I reproduce this result?
Use the same inputs and assumptions shown here. Simulation seeds reproduce the same paths. Read the calculation documentation.
Your calculation table
| Month | Balance |
|---|---|
| 1 | 10,000 |
| 2 | 10,000 |
| 3 | 10,000 |
| 4 | 10,000 |
| 5 | 10,000 |
| 6 | 10,000 |
| 7 | 10,000 |
| 8 | 10,000 |
| 9 | 10,000 |
| 10 | 10,000 |
| 11 | 10,000 |
| 12 | 10,000 |
Citable worked example
Compound interest and SIP calculator: fixed public worked-example outputs using the calculator’s published default inputs. Project lump-sum and monthly investment growth with compound interest. Include rising contributions, inflation and the first-million milestone. These illustrative figures are independent of visitor inputs and live market feeds. The table contains 12 rows and is available as CSV and JSON. Formula and assumptions reviewed 2026-09-07.
These are fixed public examples. Your calculation above does not change this table.
| Month | Balance |
|---|---|
| 1 | 10,000 |
| 2 | 10,000 |
| 3 | 10,000 |
| 4 | 10,000 |
| 5 | 10,000 |
| 6 | 10,000 |
| 7 | 10,000 |
| 8 | 10,000 |
| 9 | 10,000 |
| 10 | 10,000 |
| 11 | 10,000 |
| 12 | 10,000 |
Computed with KlarFort Calculators, https://klarfort.com/
Calculator reference: https://klarfort.com/tools/compound-interest-calculator/. Usage and credit.
Formula and assumptions
balance[m] = (balance[m-1] + contribution[m]) × (1 + annual return)^(1/12); real value = final balance / (1 + inflation)^(months/12).
- Contributions are made at the beginning of each month. Annual returns are effective rates converted to monthly compound factors. All figures use one entered currency.
- Contribution growth compounds monthly from its entered effective annual rate. Lump-sum mode ignores the monthly contribution. The first-million threshold is 1,000,000 units of the selected currency.
Assumptions reviewed:
Sources
- KlarFort calculation methodology. Free to use with the credit line; vintage 1.
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