How to Calculate SIP Returns: A Step-by-Step Guide

When you invest a lump sum in a mutual fund or fixed deposit, calculating returns is straightforward. You input your starting capital, wait a few years, and calculate the growth rate using standard Compound Annual Growth Rate (CAGR).

However, a Systematic Investment Plan (SIP) is different. With a SIP, you do not invest your money all at once. Instead, you make recurring monthly (or weekly) contributions. Because each installment compounds for a different duration, standard CAGR calculations will not give you the correct picture of your returns.

This step-by-step guide explains the math behind SIP returns, shows you how to calculate them manually, and introduces XIRR—the industry standard for tracking recurring investment performance.

1. Why Standard CAGR Fails for SIPs

Before diving into the formulas, let’s understand why standard Compound Annual Growth Rate (CAGR) fails when applied to SIPs.

CAGR measures the growth of a single payment over a specific time horizon. It assumes that the entire amount of capital was working for you from Day 1.

But in a monthly SIP, only your first installment compounds for the full tenure. The second installment compounds for one month less, the third for two months less, and so on. Your last installment (made just before the maturity date) compounds for only a single month.

If you calculate your overall SIP returns using the point-to-point CAGR formula, you will get an artificially low number. To measure the performance of a SIP accurately, you must treat each monthly payment as an independent investment or use cash-flow-adjusted return metrics.

2. The SIP Compounding Formula (Future Value of Annuity)

In finance, a series of equal, periodic payments is known as an annuity. Since a SIP consists of regular monthly contributions, we use the Future Value of an Ordinary Annuity formula to calculate the expected maturity amount.

The Formula:

FV = P × [

(1 + i)ⁿ - 1 i

] × (1 + i)

Where:

FV = Future Value (Maturity Amount of your SIP)
P = Periodic payment (monthly SIP amount)
i = Periodic interest rate. Since SIPs are monthly, we divide the annual rate by 12: i = (Annual Return Rate / 100) / 12
n = Total number of payments (number of months: Years × 12)
Note: The final × (1 + i) term accounts for payments made at the beginning of each month (Annuity Due).

Let’s Work Through a Real Example:

Suppose you start a monthly SIP of ₹10,000 for 1 year (12 months), and the fund returns an average of 12% per annum.

Monthly SIP (P) = ₹10,000
Monthly Interest Rate (i) = (12 / 100) / 12 = 0.01
Number of Payments (n) = 12

Plugging these numbers into the annuity formula:

FV = 10,000 × [

(1 + 0.01)¹² - 1 0.01

] × (1.01)

FV = 10,000 × [

1.126825 - 1 0.01

] × (1.01)

FV = 10,000 × 12.6825 × 1.01 ≈ ₹128,093

Breakdown of the Result:

Total Principal Invested: 12 months × ₹10,000 = ₹120,000
Maturity Value: ₹128,093
Net Wealth Gain: ₹8,093

If you had calculated the absolute return on this SIP, you would see a simple return of (8,093 / 120,000) * 100 = 6.74%. But because your money was deployed gradually (averaging only 6 months of active market exposure), the actual annual rate of return you earned on your cash is indeed 12.0%.

To see how these returns change when compared directly with a one-time deployment, explore our SIP vs Lump Sum Calculator.

3. Calculating Historical SIP Returns: Introducing XIRR

The annuity formula above assumes a perfectly stable, constant rate of return. However, mutual funds and equity markets do not move in a straight line. NAVs (Net Asset Values) fluctuate daily, meaning your ₹10,000 buys a different number of units each month.

To calculate the actual annualized return on your real-life, fluctuating SIP payments, we use XIRR (Extended Internal Rate of Return).

XIRR is a mathematical function that calculates the internal rate of return for a series of cash flows occurring at irregular intervals. It adjusts for both the specific date of each transaction and the varying cash amounts.

How to Calculate XIRR in Excel or Google Sheets:

If you want to track your own mutual fund portfolio, you don’t need to do the calculus by hand. You can set up a simple spreadsheet:

Column A (Dates): Enter the date of each SIP installment. Write the final withdrawal/valuation date at the very bottom.
Column B (Amounts): Enter your SIP payments as negative numbers (e.g., -10000), since they represent cash outflows. Enter the final maturity value as a positive number at the bottom.
The Formula: In a blank cell, type: =XIRR(B1:B13, A1:A13)
Press Enter, and format the cell as a percentage. This will give you your exact annualized SIP return.

4. SIP vs. Recurring Deposits (RD)

Many conservative investors choose bank Recurring Deposits (RD) as a risk-free alternative to mutual fund SIPs. While both require monthly deposits, the compounding mechanics are different:

Recurring Deposits lock in a guaranteed interest rate (usually 6% to 7.5%) compounded quarterly. The math is fixed and predictable.
Mutual Fund SIPs compound annually on average, but are subject to short-term volatility. In exchange for this volatility, equity SIPs have historically delivered 12% to 15% CAGR over 5+ year horizons.

You can run these projections side-by-side using our dedicated SIP vs RD Calculator to see how much more wealth a market-linked SIP can build over different time horizons.