How Social Security Calculates Your Primary Insurance Amount from Lifetime Earnings

Social Security does not simply average your highest-earning single year or your most recent paychecks to set your benefit; instead it sums wage-indexed earnings from your highest 35 years. Instead, the Social Security Administration sums your wage-indexed earnings from your highest 35 years and runs that figure through a multi-step formula that converts it into a single monthly figure called your Primary Insurance Amount, or PIA. Here is how SSA's Benefits Planner describes that process, from indexing old wages to applying the bend points of $1,174 and $7,078 that apply to workers whose year of eligibility is 2024, with a worked example you can follow step by step.

Step one: SSA indexes your old wages so they count in today's dollars

SSA adjusts each year's past earnings using an indexing factor before comparing them, so wages from different decades can be put on a common scale. That factor is calculated by dividing the national average wage index for the year you turn 60 by the average wage index for the specific earlier year in question. The factor equals 1 for the year you turn 60 and every year after, which means earnings from age 60 onward are counted at face value, while earnings from your 20s, 30s, and 40s get scaled up to reflect wage growth over time. There is also a ceiling on what counts in any single year: only earnings up to that year's maximum taxable earnings amount are subject to Social Security tax and can be credited toward your indexed earnings, which was $168,600 for 2024.

Step two: SSA picks your highest 35 years and calculates AIME

Once every year of earnings has been indexed, SSA determines the number of computation years — up to 35 — selects the years with the highest indexed earnings, adds up the indexed earnings from just those years, and divides the total by the number of months in that many years, which is 420 months for a 35-year computation. The result is rounded down to the next whole dollar, and that figure is your Average Indexed Monthly Earnings, or AIME. If you have fewer than 35 years of earnings on your record, SSA does not skip the missing years — it plugs in zeros for them, which pulls your average down. SSA's own published worked examples confirm this mechanic directly: lower-earning years outside the top 35 are dropped entirely from the sum, with the dropped indexed amounts shown in red in SSA's illustrations, and only the top 35 years feed into the 420-month average.

Step three: SSA converts AIME into PIA using fixed percentages and bend points

With AIME in hand, SSA applies the actual benefit formula, which splits your AIME into three slices and applies a different percentage to each slice: 90%, 32%, and 15%. The dollar thresholds that separate these slices are called bend points, and while the 90/32/15 percentages are fixed permanently by law, the bend-point dollar amounts are updated every year to track national wage growth. Which year's bend points apply to you depends on your 'year of eligibility' — defined as the year you turn 62, become disabled before 62, or die before turning 62. For anyone whose year of eligibility is 2024, the first bend point is $1,174 and the second is $7,078. That means the first $1,174 of your AIME is credited at 90%, the portion of your AIME between $1,174 and $7,078 is credited at 32%, and any AIME above $7,078 is credited at only 15%.

Worked example: a hypothetical $5,000 AIME in 2024

Suppose you are a hypothetical worker whose year of eligibility is 2024 and whose AIME, already correctly calculated from your top 35 years of wage-indexed earnings, comes to exactly $5,000 — a round number chosen here purely to make the math easy to follow, not an SSA-published figure. Using the 2024 bend points of $1,174 and $7,078, the first slice of your AIME is the full $1,174, credited at 90%. Because your $5,000 AIME does not reach the second bend point of $7,078, the remaining $3,826 of your AIME falls entirely into the 32% bracket, and there is nothing left over for the 15% bracket. Adding 90% of $1,174 to 32% of $3,826 gives a raw PIA of $2,280.92 before any final rounding. SSA's own published case example follows this identical pattern with a different AIME and year: a hypothetical AIME of $5,825 run through the 2026 bend points of $1,286 and $7,749 produces 90% of $1,286 plus 32% of the amount between $1,286 and $5,825, for a raw result of $2,609.88, which SSA then truncates down to $2,609.80 for a worker eligible and retiring in the same year.

• aime: 5000
• bend1: 1174
• Formula: (bend1 * 0.90) + ((aime - bend1) * 0.32)
• Result: 2280.92

Illustrative PIA calculation for a hypothetical worker using 2024 bend points

Why your final benefit is truncated, not rounded

SSA's published example shows the raw formula output being truncated down to the next lower ten-cent increment rather than rounded to the nearest dime — in that example, $2,609.88 becomes $2,609.80. Applying that same truncation rule to the hypothetical $5,000-AIME example above, you would take whatever raw dollar-and-cents figure the 90/32/15 formula produces and drop it down to the next lower ten-cent increment rather than rounding it, the same way SSA's own example rounds $2,609.88 down to $2,609.80 instead of up to $2,609.90. This truncation step applies specifically to a worker whose year of eligibility and year of benefit receipt are the same, meaning no cost-of-living adjustment has yet been layered on top.

• Use this table to find your own bend points: locate the year you turn 62, become disabled before 62, or die before 62 — that is your year of eligibility, and its bend points apply to your PIA formula for life, subject to later cost-of-living adjustments
• For a 2024 year of eligibility, the first bend point is $1,174 and the second bend point is $7,078
• SSA also publishes three additional dollar figures alongside these bend points ($1,500, $2,166, $2,825), but those are separate maximum-family-benefit bend points and are not used in the individual PIA formula
• Because only the dollar bend-point values change each year while the 90%, 32%, and 15% percentages stay fixed by law, a worker with a different year of eligibility would apply the same formula structure to that year's own bend-point amounts instead of the 2024 figures shown here

Bend points for a 2024 year of eligibility

Key takeaways

• Your PIA is built from your highest 35 years of wage-indexed earnings, not your most recent or highest-ever single year
• Earnings before the year you turn 60 are indexed upward using a wage-index ratio; earnings from age 60 on are counted at face value
• Fewer than 35 years of earnings means zeros fill the gaps, lowering your AIME
• The 90/32/15 percentages never change, but the dollar bend points that divide AIME into slices are updated every year
• For a 2024 year of eligibility, the bend points are $1,174 and $7,078
• The raw formula result is truncated down to the next lower dime, not rounded, when eligibility and benefit-start years match

Does a higher-earning year always replace a lower one in my 35-year average?

Yes, in the sense that SSA sums only your top 35 years of indexed earnings and drops the rest entirely, so a new high-earning year can push out whichever of your current top-35 years has the lowest indexed value.

Why are my earnings from decades ago worth more in the formula than the actual dollar amount I earned?

Because SSA applies an indexing factor to pre-age-60 earnings, calculated as the average wage index for the year you turn 60 divided by the average wage index for that earlier year, which scales up old wages to reflect wage growth since then.

What happens if I haven't worked 35 years yet?

SSA uses up to 35 years of earnings to compute your average, and fills any years short of 35 with zero earnings, which lowers your average indexed monthly earnings compared to someone with the same pay over a full 35-year career.

Do the bend-point percentages change over time?

No, the 90%, 32%, and 15% percentages are fixed permanently by law for workers whose PIA is computed under the wage-indexed formula, while only the dollar bend-point amounts separating the brackets change annually with the national average wage index.

Which year's bend points apply to my benefit?

The bend points from your 'year of eligibility' — the year you turn 62, become disabled before 62, or die before turning 62 — are the ones that apply to your PIA formula.

Is my final benefit rounded up or down?

SSA truncates the raw PIA calculation down to the next lower ten-cent increment rather than rounding to the nearest dime, at least for a worker whose eligibility year and benefit-start year are the same.

Sources

• www.ssa.gov
• www.ssa.gov
• www.ssa.gov
• www.ssa.gov
• www.ssa.gov