SIP Calculator

Created by Arunangshu DasReviewed Nov 9, 2026

Estimate how fixed monthly investments could build up under a supplied effective annual return.

Compare beginning and end of month contributions and see how much of the ending value comes from contributions.

Projected ending value

Enter a monthly plan or load the worked example.

Index 0 is the start of the first month. The final value is measured at the end of the last month. The model uses equal periods and a constant assumed return.

Understand what drives the projection

Walk through the monthly rate conversion, payment timing and signed gains.

Read the complete SIP guide

Formula and methodology

Ending value = monthly contribution × sum of the remaining monthly growth factors.

Convert the effective annual return A (as a decimal) to monthly factor f = (1 + A)^(1/12). For n months, multiply each contribution at index k by f^(n − k). Sum these terminal contributions and subtract invested principal to define the signed gain or loss.

Definitions

A systematic investment plan (SIP) is a schedule for investing a fixed amount at regular intervals. This projection models monthly contributions from a zero opening balance.

Verified worked examples

At 500 per month for 12 months and a 12% effective annual return, 6,000 is contributed. End-of-month investing projects 6,323.25, a gain of 323.25. Beginning-of-month investing projects 6,383.25, a gain of 383.25.

Interpretation

An earlier contribution has one extra month of exposure. It increases the ending value when the assumed rate is positive and reduces it when the assumed rate is negative. At zero return the ending value equals principal.

Inputs and interpretation

Enter one fixed contribution in major currency units, an effective annual percentage and the number of complete months. Choose beginning or end timing and compare principal, gain or loss and projected ending value.

Assumptions and limitations

Months are equal model periods. Index 0 is the opening checkpoint and index n is the valuation checkpoint. Beginning payments run from 0 to n−1 and end payments from 1 to n. No payments occur at zero months or with a zero contribution.

Supported domain and common mistakes

Enter up to 10^12 per month, 0 to 1,200 complete months and an annual percentage above −100% and up to 100%. Decimal inputs support 12 fractional digits. The model uses 80 significant digits and rejects ending values above 10^30. Money display rounds to two places.

Dividing an effective annual percentage by 12 changes its meaning. Keep the input in one currency and match timing when comparing with another calculator. Use separate scenarios to see the effect of changing the return assumption.

Frequently asked questions

How does a SIP calculator work?

It adds the projected value of every fixed monthly contribution at the final month and separates principal from modeled gain or loss.

What rate should I enter?

Enter the effective return over one full year as a percentage. For example, enter 12 for 12%. The equivalent monthly rate is about 0.948879%.

What if I enter zero months?

The schedule is empty. Principal, ending value and gain are zero for either timing option.

Does the last contribution earn a return?

An end-of-month payment at the valuation checkpoint has no growth period. A beginning-of-month payment in the final month has one.

Can the projection show a loss?

Yes. With a negative assumed annual rate, money exposed to growth periods shrinks. The modeled value can be below total contributions.

Can I use this for quarterly contributions?

This calculator models one fixed amount each month. Quarterly payments need a schedule with different payment indices.

Sources and educational scope

Educational constant-return projection. It excludes opening balances, irregular or step-up payments, dates, taxes, fees, inflation, FX and trading details. It provides no guarantee or personalized investment advice.

Reviewed 2026-11-09. AI-assisted content under operator editorial responsibility. No independent expert financial review is claimed.