Lumpsum formula
Future value = P × (1 + r)n
₹1 lakh invested at 12% a year for 10 years grows to about ₹3,10,585. At 6% inflation, that's worth about ₹1.73 lakh in today's money. At 12%, money doubles roughly every 6.1 years (the "rule of 72": 72 ÷ 12 = 6).
Questions people ask
Lumpsum or SIP: which is better?
If you already have the money and a long horizon, investing it at once gives it more time to grow. A SIP spreads the risk of investing just before a market fall. Many people invest part as a lump sum and the rest through a SIP or STP.
What return should I assume?
It depends on the investment: around 6–7% for fixed deposits and debt funds, and higher but uncertain returns for equity funds over long periods. Returns are not guaranteed.
Method and sources
Value = amount × (1 + rate)^years, compounded yearly. Today's value divides by (1 + inflation)^years. Doubling time = ln 2 ÷ ln(1 + rate). Returns are assumed, not guaranteed. How we calculate.
Last reviewed 22 Oct 2026 by the WealthFeedz team.