How much do I need to save monthly to reach Coast FIRE by age 35?
Scenario
Priya, age 25, software engineer in Bengaluru, current annual expenses ₹3.5 lakh
Inputs
- Coast age
- 35
- Current age
- 25
- Inflation %
- 6
- Retirement age
- 55
- Safe withdrawal rate %
- 3.5
- Annual expenses today INR
- 3,50,000
- Assumed equity return %
- 12
Calculation
- 1.
Inflation-adjust annual expenses to age 55 (30 years of 6% inflation)
₹3.5L × (1.06)^30 → ₹20.10 L
- 2.
Target retirement corpus at 3.5% safe withdrawal rate
₹20.1L ÷ 0.035 → ₹5.71 Cr
- 3.
Coast corpus at age 35 (must compound for 20 years at 12%)
₹5.71Cr ÷ (1.12)^20 → ₹59.20 L
- 4.
Monthly SIP for 10 years at 12% to reach ₹60L
₹60L ÷ 230 (SIP-FV factor) → ₹26,087
Conclusion
₹26,000/month SIP for 10 years (age 25 to 35) to reach the coast point of ₹60 lakh, which then compounds untouched to ₹5.71 crore by age 55.
Tradeoffs
Assumes 12% nominal equity return and current expenses staying flat in today's money. Each 10% real rise in expenses inflates the required coast SIP by ~10%. A market drawdown in year 8–10 of accumulation extends the SIP phase.