What it does

The SIP Calculator projects the corpus you'd build by running a monthly Systematic Investment Plan at an expected annual return for a chosen tenure. The summary cards headline the final number; the year-by-year table breaks it down so you can see exactly when compounding starts to dominate over fresh contributions.

How the math works

• Monthly compounding — annual rate ÷ 12, applied to the opening balance each month before that month's deposit lands.
• End-of-month deposits — interest accrues on existing units first, then the new SIP buy adds to the corpus. Mirrors the typical Indian SIP allocation flow.
• Closed-form for a constant SIP: FV = M × ((1+r)^n − 1) / r where M is the monthly contribution, r is the monthly rate, n is the number of months. We compute it month-by-month rather than via the closed form so v2 lumpsums + rate changes + withdrawals can layer in without rebuilding the model.
• Real value — when "Adjust for inflation" is on, real = nominal / (1 + i)^years using the inflation rate you specify.

Basic vs Advanced

• Basic — monthly contribution, expected return, tenure, optional inflation.
• Advanced — adds Started SIP on and Matures on date pickers. Editing maturity writes back into tenure so toggling between modes stays in sync. The schedule table shows absolute calendar years in advanced mode; the Final Corpus card picks up a "matures Mar 2041" hint.

Not modelled (yet)

• Lumpsum injections — one-time / quarterly / yearly extra deposits.
• Mid-tenure rate changes — switching expected-return assumptions partway through.
• Partial withdrawals (SWP) — pulling money out mid-tenure on a schedule.
• Step-up SIPs — annual percentage hike to the monthly amount.
• Taxes — equity LTCG (10% over ₹1 L), STCG (15%), debt-fund slab tax. The corpus shown is pre-tax.

Privacy

All inputs are persisted in your browser's localStorage underchorecrush:sip-calculator:v1. Refresh the page or come back tomorrow — they're still there. Nothing is sent to any server.