How Social Security Benefits Are Calculated
Your Social Security retirement benefit is not a guess and not a negotiation. It is the output of a fixed formula the Social Security Administration runs on your lifetime earnings record. If you understand the three steps of that formula, you can read your own benefit estimate like a mechanic reads a gauge: input, conversion, adjustment for timing.
Step 1: Your 35 highest-earning years become your AIME
Social Security looks at every year you paid Social Security tax, adjusts each year's earnings for wage growth, picks your 35 highest years, adds them up, and divides by 420 (the number of months in 35 years). The result is your Average Indexed Monthly Earnings, or AIME. Two details matter here. First, years you did not work count as zeros, and 35 is fixed, so a short career drags the average down. Second, working an extra year at high pay does not just add income; it can replace a low or zero year in your top 35, which lifts your average more than you might expect.
Step 2: Indexing levels the playing field across decades
A dollar earned in 1990 is not the same as a dollar earned in 2024, so SSA indexes your past earnings to the national average wage level of the year you turn 60. Earnings after age 60 are counted at face value. This is why your statement's earnings history matters more than any single year's pay stub: the formula rewards a long, steady record, and each year's contribution is measured against the wages of its own time.
Step 3: Bend points turn your AIME into your PIA
The Primary Insurance Amount (PIA) is the monthly benefit you would receive if you claimed at your full retirement age. SSA computes it from your AIME with a three-bracket formula that favors lower earners. For workers who first become eligible in 2026, the bend points are $1,286 and $7,749 (source: ssa.gov/oact/cola/piaformula.html):
- 90% of the first $1,286 of AIME
- 32% of AIME between $1,286 and $7,749
- 15% of AIME over $7,749
The 90/32/15 percentages are set by law and never change; the dollar bend points rise each year with average wages. The result is rounded down to the next lower dime.
Worked example: AIME of $6,000
Take a worker with an AIME of $6,000 a month using the 2026 formula. The first $1,286 falls in the 90% bracket: $1,286 x 90% = $1,157.40. The remaining $4,714 ($6,000 minus $1,286) falls in the 32% bracket: $4,714 x 32% = $1,508.48. Nothing reaches the 15% bracket. Add them: $1,157.40 + $1,508.48 = $2,665.88, rounded down to the next dime, for a PIA of $2,665.80 a month. That is the benefit at full retirement age, before any adjustment for claiming early or late.
What moves your number most
Three levers matter more than anything else. First, eliminate zero years: if you have fewer than 35 years of earnings, every additional working year replaces a zero. Second, replace low years with high ones late in your career, when your pay is typically highest. Third, claim timing: your PIA is the center of the seesaw, and claiming at 62 versus 70 swings the monthly check by more than 75% of its value. The breakeven calculator on this site applies the official reduction and delayed-credit formulas to your own PIA.
Where to see your numbers
You do not need to compute any of this by hand for planning. Your my Social Security account at ssa.gov shows your official earnings record and estimated benefits at 62, full retirement age, and 70. Check the earnings record for errors first; a missing year of wages is the most common and most fixable reason a benefit comes out lower than expected.
Frequently asked questions
What is AIME?
AIME stands for Average Indexed Monthly Earnings. It is the average of your 35 highest-earning years, with each year's wages adjusted for national wage growth, divided by 420 months. It is the input to the benefit formula, not the benefit itself.
What are bend points?
Bend points are the dollar thresholds in the PIA formula where the percentage applied to your AIME drops: 90% below the first bend point, 32% between the two, 15% above the second. For 2026 they are $1,286 and $7,749, per ssa.gov.
Why does Social Security replace more of a low earner's wages?
The 90/32/15 formula is progressive by design: the first slice of earnings counts at 90%, so lower earners get a higher replacement rate. Higher earners get larger checks in dollars, but a smaller share of their pre-retirement income.
Does working past full retirement age raise my benefit?
It can, two ways. Additional high-earning years can replace low or zero years in your top 35, raising your AIME and PIA. And each month you delay claiming past your full retirement age (up to 70) adds delayed retirement credits of 8% per year for workers born in 1943 or later.