Every calculator on NPSCalculator.org.in uses the formulas below. We publish them so you can check our work, and so you know exactly what each result assumes.
General conventions
- Monthly investments are added at the start of each month and compounded monthly at the annual rate / 12 (annuity-due), the convention used by most SIP and NPS calculators.
- Step-up applies once every 12 months.
- Results are in nominal (future) rupees unless the calculator says otherwise.
- All calculation happens in your browser. Inputs are not sent to our server; the share link stores them only in the URL.
NPS
Corpus = sum over months of (contribution x (1 + r/12)^(months remaining)) [simulated month by month] Annuity = Corpus x annuity share; Monthly pension = Annuity x annuity rate / 12; Lumpsum = Corpus - Annuity
Exit rules follow the PFRDA (Exits and Withdrawals) Amendment Regulations, 2025: non-govt up to 80% lumpsum; full withdrawal up to Rs. 8 lakh; Rs. 6 lakh lumpsum plus SUR for Rs. 8 to 12 lakh; premature exit 20:80 above Rs. 5 lakh; govt sector 60:40. Government NPS uses 10% employee and 14% Government on Basic + DA. Auto Choice glide paths are approximated linearly from age 35 to 55.
UPS
Payout = 50% x average basic (last 12 months) x min(service, 25) / 25, minimum Rs. 10,000 (service 10+ years) Dearness Relief = Payout x DR%; Family pension = 60% of payout + DR Lumpsum = (basic + DA) / 10 x completed six-month periods; Payout reduced pro rata for corpus withdrawn
Old Pension, EPS-95, gratuity
OPS pension = 50% of last basic (min Rs. 9,000); commutation = 40% x pension x 12 x 8.194 EPS pension = pensionable salary (max Rs. 15,000) x (service + 2 if 20+ yrs) / 70 Gratuity (Act) = Basic + DA x 15/26 x years (6+ months rounds up), cap Rs. 20 lakh Gratuity (Central Govt) = emoluments / 4 x half-years, max 16.5 x emoluments, cap Rs. 25 lakh
Savings schemes
- PPF and SSY: yearly deposit at the start of the year, compounded annually. SSY deposits for 15 years, maturity at 21.
- NSC: annual compounding for 5 years. KVP: doubling period from the notified rate.
- RD: each instalment compounded quarterly for its remaining months.
- FD: P x (1 + r/n)^(n t) with the chosen compounding.
- EPF: employee 12%; employer 12% minus EPS (8.33% of wages up to Rs. 15,000).
- Rates are taken from our settings, updated each quarter from official notifications.
Tax
Income tax uses FY 2026-27 slabs (new regime unchanged from FY 2025-26), standard deduction (Rs. 75,000 new, Rs. 50,000 old), section 87A rebate with marginal relief in the new regime, surcharge and 4% cess. Surcharge marginal relief is not modelled.
Limitations
Market-linked returns are assumptions, not forecasts. Annuity rates vary by insurer. Rules for specific cases (state governments, armed forces, disability, etc.) may differ. Always confirm with official sources before acting.