The useful bit: Check whether the annual return is effective or nominal, and whether contributions arrive at the beginning or end of each month.
The amount is only one part of the model
If two tools show different future values for the same monthly deposit, neither difference should be ignored. A SIP projection also needs a return convention, contribution dates, a number of periods and rules for fees or withdrawals. A number without those assumptions is difficult to interpret.
CalculateKro treats the annual return in its SIP tool as an effective annual assumption. It converts that rate to a monthly equivalent using (1 + annual return) to the power of one-twelfth, minus one. This makes twelve consecutive model months compound back to the stated annual rate.
Dividing by twelve is a different convention
An annual nominal rate divided by 12 produces a monthly periodic rate. Once that rate compounds twelve times, its effective annual rate is a little different. Both conventions can be useful in their proper context; the mistake is comparing them as if they describe the same assumption.
For an easy check, set the return to zero. A ₹5,000 monthly contribution for 12 months produces ₹60,000 of contributions and a final balance of ₹60,000. Any fees aside, there should be no modelled gain. This is a useful baseline when checking a tool.
Timing changes time in the market
A contribution at the beginning of a month earns that month’s assumed return. A contribution at the end does not. Under a positive constant return, beginning-of-month payments therefore finish with a higher modelled balance. Under a negative return, they experience one more period of loss.
The page lets you choose that timing explicitly. It assumes equal contributions with no skipped months. A real contribution history with changing payments and dates is a different cash-flow problem.
A smooth chart is not a promise
A projection draws a smooth path because the input is a constant rate, not because markets behave that way. Actual returns vary and can be negative. The displayed gain also excludes fund costs, exit charges, tax and inflation unless a tool explicitly says otherwise.
Use scenarios to understand sensitivity. Compare a lower return, a zero-return case and your own assumption. The tool does not recommend a fund or provide a personalised investment plan. Its job is to make the arithmetic and assumptions visible.