sip-calculator
A SIP (systematic investment plan) calculator estimates the future value of a recurring monthly investment in a mutual fund or index fund using the future-value-of-annuity formula FV = P × [((1+r)^n − 1) / r] × (1+r), where P is the monthly contribution, r the monthly return, and n the number of months. The ZTools SIP Calculator runs in the browser, lets you compare multiple expected return scenarios (conservative 8% / moderate 12% / aggressive 15%), shows the principal-vs-returns split visually, and is for educational planning — actual mutual-fund returns vary, past performance does not predict future performance, and tax / fee impact is not included.
Use cases
Long-term retirement planning
Person investing $500/month for 30 years at 12% expected return — calculator shows ~$1.5M end value, with $180K contributions and $1.32M returns from compounding.
Goal-based saving
Targeting $100,000 in 10 years at 10% expected return — calculator works backward to required monthly SIP.
Comparing scenarios
Side-by-side 8% / 12% / 15% to see how return assumptions dramatically swing end value over decades.
Educational impact illustration
Showing students or new investors how compounding works on real numbers — visceral demonstration of why starting early matters.
How it works
- Enter monthly investment — How much you can invest each month (your SIP amount).
- Enter expected annual return — Your assumption — equity index funds historically returned ~10–12% over very long periods, but past performance is not a guarantee.
- Enter tenure — Number of years you plan to invest.
- Compute future value — Future-value-of-annuity formula. Monthly compounding. Returns total invested + total returns + grand total.
- Visualise — Stacked bar showing principal vs returns across time. Optional comparison of 3 scenarios.
Examples
Input: $500/month, 12% annual, 30 years
Output: Invested $180,000 · Returns ~$1.32M · End value ~$1.5M
Input: $1,000/month, 10% annual, 20 years
Output: Invested $240,000 · Returns ~$485K · End value ~$725K
Input: Goal: $100K in 10 years at 10%
Output: Required SIP ≈ $483/month
Frequently asked questions
Are these returns guaranteed?
No. Returns are an assumption. Equity returns vary widely over short periods. Long horizons (20+ years) historically smooth out, but past performance does not guarantee future results.
What return rate should I use?
Conservative: 8%. Moderate: 10–12% (broad equity index historical average). Aggressive: 15% (rarely sustainable long-term). Run multiple scenarios.
Does it factor inflation?
No — by default, the future value is in nominal currency. To see "real" purchasing power, deflate by expected inflation (e.g., subtract 3% from your return assumption to approximate real return).
Are taxes included?
No — the calculator shows pre-tax future value. Capital-gains and other taxes vary by jurisdiction and product structure (e.g., tax-advantaged accounts vs taxable). Plan accordingly.
What about fund fees?
Not included by default. Subtract the expense ratio from your return assumption — a 1% expense ratio on a 10% return reduces compound growth meaningfully over decades.
Can I model variable contributions?
The calculator assumes fixed monthly amounts. For step-up SIPs (increasing contributions yearly), use the "annual increase" option if available; otherwise approximate by averaging.
Tips
- Start early — a 10-year head start often beats double the contribution started later.
- Run conservative AND aggressive scenarios; reality usually lies between.
- Subtract expected inflation and fees to think in real terms.
- Stay consistent — monthly contributions through bear markets are when SIPs build the most value.
- Rebalance and review yearly, but resist the urge to time the market.
Try it now
The full sip-calculator runs in your browser at https://ztools.zaions.com/sip-calculator — no signup, no upload, no data leaves your device.
Last updated: 2026-05-05 · Author: Ahsan Mahmood · Edit this page on GitHub