Take ₹5,000 a month for 10 years at an assumed 12% a year. You pay ₹6,00,000 in total. The SIP calculator shows a future value near ₹11.6 lakh. The gap is not a bonus added at the end. It is the assumed growth on each instalment from the month it is paid.
Earlier money has longer to grow
The first instalment is assumed to earn the monthly rate for all 120 months. The last instalment has just been paid, so it has barely grown. That is why the yearly table’s “gain” column starts small and then steepens. The same ₹5,000 does not do the same work in year 1 and year 10.
How the page turns the rate into a month
An annual rate of 12% is split into a monthly rate of 1%. Each instalment is treated as paid at the start of the month. The future value is the monthly amount, times the growth of that series, times one extra month of growth. Invested amount is simply the monthly figure times the number of months. Gain is future value minus invested amount.
- Change the return and only the gain changes. The invested column stays put.
- A higher return does not make the plan safer. It makes the illustration larger.
- Costs, tax, and a missed month are outside this sum.
Use the yearly table to see the path, not just the last cell. If the path only looks acceptable at a return you do not believe, the last cell is the wrong number to plan around.