Backtest a SIP or lumpsum in any mutual fund

The question it answers

"What would I have now if I had started a SIP in this fund five years ago?" A SIP calculator answers that with a return you assume. The backtest on every fund page answers it with the fund's own NAV history, day by day, so the result includes every fall the fund actually went through. It needs no account.

This post walks through the card using one fund, UTI Nifty 50 Index Fund Direct Growth, with NAVs up to Wednesday 15 October 2026.

Step 1: find the card

On any fund page, use the Backtest tab in the strip that pins under the header, or scroll to the card titled "Backtest this fund". It sits after Rolling returns and before Calendar-year returns. The card appears for any fund with at least two NAV points.

Step 2: choose SIP or Lumpsum and an amount

Two tabs sit at the top: SIP and Lumpsum. The SIP tab takes a "Monthly investment (₹)", set to ₹10,000 when the page loads, up to ₹10 crore. The Lumpsum tab takes a "Lumpsum amount (₹)", set to ₹1,00,000, up to ₹100 crore.

Step 3: pick a period

The Period buttons are 1Y, 3Y, 5Y, 10Y and Max. A button is greyed out when the fund is younger than that period, and the card opens on the longest of 5Y, 3Y or 1Y that the fund's history covers. Max starts at the first NAV the site holds. For Direct plans that is no earlier than January 2013, when Direct plans began.

What it computes

For a SIP, the card buys on the same day of the month as the latest NAV, going back one month at a time, at the first NAV on or after each date. All units are valued at the latest NAV. Four tiles show Invested, Current value, Absolute return and XIRR. XIRR annualises the result while allowing for each instalment's date. A chart titled "Value vs. invested" plots both lines month by month.

For a lumpsum, the card buys once at the first NAV on or after the start date and shows Invested, Current value, Absolute and CAGR. A line under the chart gives the buy date and the units bought. CAGR shows a dash for periods under one year, where annualising would mislead.

A worked example: UTI Nifty 50 Index Fund

Same fund, same end date, both modes, as the card on the UTI Nifty 50 Index Fund page shows them. SIP of ₹10,000 a month:

Lumpsum of ₹1,00,000:

The 3-year row is the one worth stopping on. A lumpsum invested in October 2023 was up 19.94%. A SIP over the same three years was slightly under water. Both are correct. The lumpsum bought everything at the 2023 price. The SIP bought much of its units in 2024 and 2025 at higher prices, and the index fund was down 11.29% in 2026 by 15 October. A SIP is always most exposed to the last stretch of its own period, which is the point made in a SIP started at the January 2026 peak.

Over ten years the gap closes: 10.15% XIRR for the SIP against 11.49% CAGR for the lumpsum. Choosing between the two is a question about when you have the money, covered in the SIP vs lumpsum guide.

Reading it next to the rest of the page

A backtest is one start date per period. Change the start by a month and the answer changes. The Rolling returns card on the same page (free account needed) shows every 3-year window instead of one, and every 5-year Nifty 50 SIP since 1999 shows how wide that spread can be. The XIRR guide explains why the SIP figure is an XIRR and the lumpsum figure a CAGR.

What the backtest does not do

• It does not deduct stamp duty, exit load or capital gains tax. The NAV already has the expense ratio taken out.
• It does not model a step-up SIP, a pause or a missed instalment. Each SIP instalment is the same amount every month.
• It covers one fund only. A compare page puts a 5-year SIP XIRR for two funds side by side.
• It is history. A good backtest says the fund did well over a stretch that has already happened, and nothing about the next one.

The formulas are on the methodology page. None of this is a recommendation to buy or sell any fund.