Compound Interest Calculator
Understand your growth, explore goals and compare the choices you can afford.
How this calculator works
1. Choose your contributions
Use SIP for monthly contributions, Lumpsum for an initial investment, or Both. An optional annual SIP increase starts in Year 2.
2. Define the return assumption
The default nominal rate is divided by 12. The annualized option uses (1 + annual rate)^(1/12) − 1. Enter rates as percentages; the formulas use decimal rates.
3. Read the projection
With beginning-of-month contributions, the monthly closing value is (opening value + contribution) × (1 + monthly rate). End-of-month contributions are added after growth.
Life events add investments, request expenses or pause regular SIPs. Event investments and expenses settle at the beginning of the month; regular SIPs retain their chosen timing. Contributions include event investments, while gains include growth on amounts later withdrawn. Unfunded expenses are shown separately. Goal-date and waiting tools use the same assumptions.
Compound growth means that earlier gains can generate further gains. These illustrations use explicit return assumptions, with optional V3 fees. Taxes are not calculated. Real investments can lose value. The calculator helps explore assumptions; it does not recommend an investment.
Questions about the calculator
How do life events change the projection?
Add up to eight extra investments, expenses or SIP pauses. Month 1 is the first modelled month. Extra investments and expenses occur at the beginning of their selected month; regular SIPs follow your timing setting. Amounts are future rupees with no automatic inflation. Money events may repeat every 12 months. Pauses overlap without being counted twice, and the original annual step-up calendar continues. Unfunded expenses are reported and are not treated as paid or as debt.
How is the goal date found?
Using the current investment amount, the tool checks monthly closing balances for up to 50 years and finds the first month reaching your future-rupee goal. It includes life events and stops if an earlier expense cannot be funded or contributions exceed the supported limit. Later expenses can reduce the balance again. This search does not change the duration of the main projection.
What does the cost of waiting comparison mean?
It delays regular SIPs by one, three or five years while preserving the original deadline. Existing capital stays invested and life events retain their dates. Annual SIP increases begin one year after the delayed start. Catch-up SIPs seek to fund events and match the original start-today projected balance; they are separate from the required SIP for your target.
How are SIP and lumpsum investments calculated?
The initial investment is added at Year 0. A SIP adds money each month, at the beginning or end according to your setting. Each month the balance grows at the selected monthly rate; V3 can place weekly, quarterly or annual contributions within that same ledger. Both mode includes the initial investment and monthly contributions. Explicit extra-investment events apply in all modes, including SIP and Lumpsum.
Why does 12% give more than 12% annual growth in the default setting?
The original nominal convention divides 12% by 12 and applies 1% each month. This gives about 12.68% effective annual growth. Select Annualized in Calculation settings to use a monthly rate that produces exactly 12% growth over a full year for money invested throughout that year.
Are these actual mutual fund returns?
No. These are illustrations based on a return assumption or an explicit hypothetical return path you choose. Mutual fund values vary, can fall, and do not pay guaranteed compound interest. The projection is not an actual portfolio return, a fund recommendation or a prediction.
When does the annual SIP increase start?
An annual SIP increase first applies in month 13, at the start of Year 2, and repeats each year. It increases your monthly contribution, not the return rate. The calculator supports contributions up to ₹5 lakh per month, including future increases.
How does inflation affect the result?
The optional inflation view divides the estimated future value by (1 + your annual inflation assumption) raised to the number of years. It shows purchasing power in today’s money. It does not change the nominal projection, monthly contributions or the target amount.
What does Plan a target calculate?
It estimates the starting monthly contribution needed to reach your future target under the selected assumptions, including any initial investment and annual SIP increase. The amount is rounded up to a whole rupee. If the initial investment already covers the hypothetical target, the required monthly contribution is zero.
Are taxes, fees and losses included?
Legacy monthly plans retain their original conventions. Explicit V3 assumptions support negative returns, contribution and compounding frequencies, dated flows, optional fees and deterministic return paths. Taxes are not calculated. Enter gross returns when applying an explicit fee, or net returns with a zero fee. Scenarios are hypothetical, not guaranteed outcomes.
Can I save or share the calculation?
Share plan creates a validated versioned link containing the inputs and calculation assumptions, after a privacy notice. Anyone with that link can see them. Export CSV downloads the yearly breakdown and assumptions. No account is required, and the calculations run in your browser.
Planning for retirement?
Explore a separate illustration of future expenses and a retirement corpus.