What this comparison measures
This page compares two start ages using the monthly amount you enter for full retirement age, often called the primary insurance amount (PIA). The birth year sets full retirement age. A full birth date is optional; when supplied, the date takes precedence over the separate year field. SSA applies the prior-year convention to a January 1 birthday, and the result identifies that adjustment. The tool covers people born in 1943 or later.
The table also shows each whole claim age from 62 through 70. Those rows use the same PIA and birth-year rule as the two-age comparison, so they are useful for seeing how the early reduction and delayed credits change a monthly amount. They do not include a personal earnings record or family benefit.
Formula used for the monthly amounts
Before full retirement age, the model reduces the PIA by 5/9 of 1% for every month in the first 36 months before FRA, then by 5/12 of 1% for each earlier month beyond that. After FRA, it adds 2/3 of 1% for each month delayed, stopping at age 70. The reduction or credit is applied as a factor to the entered PIA. FRA is 66 for 1943–1954 births, rises by two months per birth year for 1955–1959, and is 67 from 1960 onward. January 1 births use the preceding year for this age calculation.
For cumulative totals, the script adds each monthly payment from the selected start month through the month before each horizon. The optional COLA compounds by whole years after age 62. The discount rate reduces a later payment by its distance in months from age 62. Break-even is the first month at which the later claim's cumulative modeled payments catch up with the earlier claim's total. This is nominal arithmetic adjusted only by the assumptions you provide.
Worked hypothetical example
Assume a hypothetical person born in 1960 has a $2,000 monthly PIA, claims at 62 versus 70, and enters 0% COLA and 0% discount. FRA is 67, or 804 months. Age 62 is 60 months early: 36 months at 5/9 of 1% equals 20%, and 24 months at 5/12 of 1% equals 10%, leaving 70% of PIA, or $1,400 monthly. Waiting to 70 adds 36 months of credits at 2/3 of 1% each, a 24% increase, giving $2,480 per month. Running those values through the script gives a break-even near age 80.4; it compares actual monthly streams rather than dividing a single difference by a monthly gap.
How to read it carefully
The result depends strongly on the PIA and the two assumptions. A positive COLA grows later checks, while a positive discount rate gives less present weight to checks received farther in the future. The cumulative rows run through ages 80, 85, and 90, and display totals in dollars without a forecast about future inflation or investment returns.
This is not a life-expectancy model. It leaves out taxes, Medicare deductions, earnings after claiming, family and survivor benefits, changes to the earnings record, and the value of income protection later in life. It does not decide what age fits a reader. The official estimate based on an individual's record is available through my Social Security.
Common input mistakes
Enter the monthly amount at FRA, not a reduced age-62 amount. If using the date field, check that the date is accurate because it replaces the birth year; January 1 receives the special prior-year treatment. The COLA and discount fields are scenarios, not official forecasts. Comparing two ages with the same values makes the modeled trade-off easier to interpret, while changing several assumptions at once makes the source of a change less obvious.
For SSA's official age-reduction explanation, use the linked source. This tool is an independent arithmetic aid, not an SSA estimator, and your official benefit is on your my Social Security statement.