Mutual Fund Calculator
This mutual fund calculator projects the future value of a fund investment that combines a one-time lump sum with monthly systematic-investment-plan (SIP) contributions, and it isolates how much the fund's expense ratio quietly costs you. It compounds your money monthly at the expected return, then re-runs the projection at the return net of the expense ratio so the gap between the two reveals the fee drag. The output shows the projected net value, the lifetime expense impact, and your net gains over what you actually contributed.
Formula
FV = P(1 + i)ᴺ + PMT · [((1 + i)ᴺ − 1) / i], i = (return − expense)/100/12
- P
- Initial lump-sum investment
- PMT
- Monthly SIP contribution
- i
- Monthly net rate = (expected return − expense ratio) ÷ 100 ÷ 12
- N
- Total months = years × 12
- FV
- Projected fund value net of the expense ratio
How it works
- Enter your initial lump-sum investment, the fixed monthly SIP amount, the expected annual return, the fund's expense ratio, and the number of years. Contributions are compounded monthly (12 periods per year) at the end of each month.
- The calculator runs the future-value projection twice: once at the gross expected return and once at the net return (expected return minus expense ratio). The difference between the two is the cost the expense ratio imposes.
- It reports the projected fund value net of fees, the total expense impact in dollars, and your net returns, calculated as the net value minus everything you put in (the initial amount plus all SIP contributions).
Worked example
A $10,000 initial investment plus $500 monthly SIP, an expected 12% return, a 1% expense ratio, over 20 years.
- Net return: 12% − 1% = 11%, so the monthly rate is 0.11 ÷ 12.
- Total contributions: 10,000 + 500 × 12 × 20 = $130,000.
- Compounding the lump sum and monthly SIPs at the net rate over 240 months gives the projected net value.
Projected net value is about $522,169, net gains over contributions are about $392,169, and the 1% expense ratio costs roughly $81,384 over the 20 years compared with paying no fee.
Frequently asked questions
- What is an expense ratio and why does it matter so much?
- The expense ratio is the annual percentage a fund charges to cover management and operating costs. Because it is deducted from your return every year and the lost amount no longer compounds, even a 1% ratio can cost tens of thousands of dollars over a multi-decade horizon.
- What is a SIP?
- A systematic investment plan (SIP) is a fixed amount invested at regular intervals, here monthly. It spreads purchases over time, smoothing out the effect of market swings and building the position steadily alongside any initial lump sum.
- Are returns guaranteed?
- No. The expected return is an assumption you provide, not a promise. Real mutual fund returns vary year to year and can be negative, so treat the projection as an illustration of compounding under a steady assumed rate rather than a forecast.
- Does this calculator account for taxes or sales loads?
- No. It models only the expense ratio against your assumed return. Capital gains taxes, dividend taxes, front-end or back-end sales loads, and inflation are not included and would further reduce your real take-home result.