How it works
The basic pension amount of the National Pension old-age pension is calculated by adding the average income of all insured members (A value) and your own average income (B value), then multiplying by a proportional constant for the period you contributed. Because the A value is included, the lower your income, the higher the pension relative to your income, which makes it a redistributive structure.
Basic pension (annual) = proportional constant × (A + B) × (1 + 0.05 × years of contribution beyond 20) | Monthly pension = basic pension ÷ 12
The proportional constant depends on when you contributed. It was 2.4 for 1988 to 1998 and 1.8 for 1999 to 2007; from 1.5 in 2008 it falls by 0.015 each year, reaching 1.245 in 2025 (income replacement rate 41.5%), and under the 2025 pension reform 1.29 (income replacement rate 43%) applies from 2026. With a contribution period of 10 years or more but less than 20, you get 50% at 10 years and 5% more for each additional year. With less than 10 years, you receive a lump-sum refund instead of a pension.
Assumptions and simplifications
The 2026 A value is KRW 3,193,511, and the standard monthly income is capped at KRW 6,590,000 and floored at KRW 410,000 (July 2026 to June 2027). The age payments start is 61 for those born 1953 to 1956, 62 for 1957 to 1960, 63 for 1961 to 1964, 64 for 1965 to 1968, and 65 for those born in 1969 or later. Early payment reduces the pension by 6% per year, up to 5 years (30%), and deferred payment increases it by 7.2% per year, up to 5 years (36%). (Source: National Pension Service notice on the 2026 upper and lower limits of standard monthly income, pension reform Q&A, checked October 2026)
The actual pension takes into account the revaluation rate that converts past income into present value, income changes during your contribution period, a separate formula for contributions made before 1998, childbirth and military service credits, dependent family pension supplements, and annual inflation adjustments. This calculator is a simple estimate that takes average income in present value and assumes a continuous contribution period. For an exact estimate, check "Find out my pension" on the National Pension Service website.