How Social Security Calculates Your Monthly Benefit

The Social Security benefit formula sounds complicated but follows a clear logic. Your monthly check is based on three things: how much you earned over your career, your Full Retirement Age, and the age you choose to claim.

Step 1 — Your 35 Highest Earning Years

SSA takes your highest 35 years of earnings, adjusts each year for inflation (using a process called "wage indexing"), and averages them. This gives your Average Indexed Monthly Earnings (AIME).

If you worked fewer than 35 years, the missing years count as zeros — which lowers your AIME and therefore your benefit. Working a few extra years in a lower-income period can still help if it replaces a zero year.

Step 2 — The Bend Point Formula

SSA applies a progressive formula to your AIME, replacing a higher percentage for lower earners. This means lower-wage workers receive a higher proportion of their earnings as benefits compared to higher-wage workers — the system is designed to provide a stronger floor for those who need it most.

Step 3 — Your Full Retirement Age (FRA)

Your FRA is determined by your birth year. For most seniors today, FRA is 66 or 67. The benefit calculated in step 2 is your "primary insurance amount" (PIA) — what you get if you claim exactly at FRA.

Step 4 — Claiming Age Adjustment

Claiming before FRA permanently reduces your benefit. Claiming after FRA permanently increases it. The adjustments are:

• Before FRA: Benefit reduced by ~5/9% per month for the first 36 months early, then ~5/12% per additional month early. Maximum reduction at 62 is ~25–30%.
• After FRA: Benefit increases by 8% per year (2/3% per month) for every year you delay up to age 70. No additional credit after 70.