SIP Calculator — Estimate Your Mutual Fund Returns
Calculate how much your monthly investments could grow over time. Works in GBP, EUR, USD, or INR — built for investors in the UK, Europe, US, and globally.
How the SIP Calculator Works
A Systematic Investment Plan, or SIP, is simply a fixed amount invested at regular intervals — most commonly monthly — into a mutual fund, index fund, or similar investment. Instead of trying to time the market with a lump sum, you invest the same amount every month whether prices are high or low. Over years, this approach tends to smooth out volatility and lets compounding do the heavy lifting.
This calculator works in GBP, EUR, USD, or INR — pick your currency above and enter three numbers: how much you plan to invest each month, the annual return rate you expect, and how many years you'll keep investing. The calculator then shows your estimated maturity value, split between what you actually put in and what came from growth.
The SIP Formula
| Symbol | Meaning |
|---|---|
| M | Maturity value — what your investment grows to |
| P | Monthly investment amount |
| i | Monthly return rate (annual rate ÷ 12 ÷ 100) |
| n | Total number of monthly investments (years × 12) |
A Quick Example
Say you invest £200 a month for 15 years, expecting an average annual return of 10% — a fairly typical long-term assumption for a diversified equity index fund. Over those 15 years, you'd put in £36,000 of your own money. At 10% average growth, the calculator estimates a maturity value of roughly £82,000 — meaning compounding contributed around £46,000 on top of what you actually paid in.
What Counts as a "Realistic" Return Rate?
This is where a lot of online calculators get used unrealistically — people plug in 15% or 20% because it makes the result look exciting. Here's a more grounded view based on long-term historical averages for diversified equity index funds:
| Investment Type | Typical Long-Term Annual Return | Risk Level |
|---|---|---|
| Global equity index fund | 7% – 10% | Medium-High |
| UK/European blue-chip index | 5% – 8% | Medium |
| Balanced fund (60/40) | 4% – 6% | Medium-Low |
| Bond-heavy fund | 2% – 4% | Low |
Honestly, running the calculation twice — once at a conservative rate (say 5-6%) and once at a more optimistic rate (8-10%) — gives you a realistic range rather than a single number you might anchor on too heavily. The truth will land somewhere in between, and probably won't follow either line exactly.
Why Time Matters More Than the Monthly Amount
Here's something the numbers make obvious but people underestimate: starting earlier matters more than investing more. Someone investing £150/month for 25 years at 8% ends up with considerably more than someone investing £300/month for 12 years at the same rate — despite putting in roughly the same total amount. The extra years of compounding do more work than the extra monthly contribution. Try both scenarios in the calculator above and see for yourself.
Frequently Asked Questions
What is a good monthly SIP amount to start with?
There's no universal "right" amount — what matters is that it's sustainable. A common approach is starting with whatever you can invest consistently without affecting essential expenses, even if that's a relatively small amount, and increasing it as income grows. Consistency over a long period matters far more than the starting amount.
Is SIP better than investing a lump sum?
It depends on timing and discipline. A lump sum invested at the right moment can outperform a SIP — but predicting the right moment is notoriously difficult. SIP removes that guesswork by spreading investment over time, which tends to reduce the impact of buying at a market peak. For most people investing from regular income rather than a windfall, SIP is also simply more practical.
Can I change my SIP amount later?
Yes — most platforms allow you to increase, decrease, pause, or stop a SIP at any time. Many investors increase their monthly amount annually in line with salary increases, sometimes called a "step-up SIP." Our Step-up SIP Calculator models this if you want to see the impact of gradually increasing contributions.
Does this calculator account for inflation?
No — this calculator shows the nominal maturity value based on your inputs. To understand what that amount is worth in today's money, you'd need to separately account for inflation. Our Inflation Calculator can help you see how purchasing power changes over the same time period.
What's the difference between SIP and lumpsum calculators?
This calculator assumes regular monthly contributions over time. If you're investing a single amount upfront instead — say, a bonus or inheritance — use our Lumpsum Calculator instead, which compounds a one-time investment rather than recurring ones.