Split each salary raise between investing and lifestyle. Watch wealth compound year on year.
Net take-home = gross × (1 − tax). All investing happens from net income.
How much of your current net salary already goes to SIP.
= Gross × (1 − tax) × (1 − base invest %). The amount you actually live on today.
Year 40 spend: —
Each raise is compounded: a higher salary next year means a bigger raise, of which the invested % gets added to your monthly SIP permanently.
Orange line: corpus remaining. Green dashed line: what you're spending that year (inflated). When orange hits zero, money runs out.