Step-Up SIP Calculator

Your monthly SIP stays the same for 12 months, then rises by the step-up percentage for the next 12, and so on. The increase compounds: with ₹10,000 and a 10% step-up, you invest ₹10,000 a month in year 1, ₹11,000 in year 2 and ₹12,100 in year 3. Each instalment is treated as invested at the start of the month and grows at the expected return divided by 12, compounded monthly.

With the default inputs (₹10,000 a month, 10% step-up, 12% expected return, 15 years):

• Total invested: about ₹38,12,698
• Maturity value: about ₹86,83,849
• Estimated returns: about ₹48,71,152
• Monthly SIP in the final year: about ₹37,975

That last number is not shown on the result card but is worth working out: starting SIP × (1 + step-up)^(years − 1). It tells you whether the plan is realistic for your income 15 years from now.

Starting at ₹10,000 a month with a 12% expected return, here is how different step-up rates compare with a flat SIP:

Read the invested column as carefully as the maturity column. Over 15 years, a 10% step-up produces about ₹36.4 lakh more than the flat SIP, but you also put in about ₹20.1 lakh more. Much of the extra corpus is extra money, not extra compounding. The real advantage is timing: to reach the same ₹86.8 lakh with a flat SIP you would need about ₹17,210 a month from the first month. A step-up lets you start at a level you can afford now and pay more when your income is higher.

Link the step-up to how you expect your income to grow, not to the size of the corpus you want.

• At or below your expected salary growth: the SIP stays roughly the same share of your take-home pay. This is the safest choice.
• Above your salary growth: the SIP eats a larger share of your income every year. Check the final-year amount. At 15% for 20 years, the SIP reaches about ₹1,42,318 a month in the last year; at 5%, about ₹25,270.
• Uneven income: pick a lower step-up you can always meet, and add a lumpsum in good years instead.

Expenses also tend to rise with time, through rent, school fees and loan EMIs, so not every rupee of a raise is free to invest. A modest step-up that you keep for the full term beats an ambitious one you abandon after a few years.

• Treating the return as fixed. 12% is an assumption. Equity returns vary every year, so rerun the plan at 10% and 8% before you commit.
• Reading the maturity in today's money. ₹86.8 lakh in 15 years will buy far less than ₹86.8 lakh today, because prices rise in the meantime.
• Comparing plans at different returns. When you compare a step-up SIP with a flat SIP, keep the return and period identical, or the comparison means nothing.
• Ignoring tax and costs. The result is before fund expenses and before tax on gains.