Inputs you will enter
- From and to datesThe first and last day of each period at one rate of pay. A new SF-50 with a new rate starts a new period. Up to six rows; leave the rest blank.
- Annual rateThe full-time annual rate of basic pay for that period, locality included. Find it on the SF-50 or in the GS pay lookup. Do not add overtime, awards or bonuses.
- Hours a week40 for full-time. Enter your scheduled hours for any part-time period; the calculator still uses the full-time rate, as OPM does, and reports the proration factor separately.
How we compute it
OPM defines the high-3 as the largest annual rate that results from averaging your rates of basic pay over any 3 consecutive years of creditable service, with each rate weighted by the time it was in effect (OPM, retrieved 2026-10-13). We count time on OPM's 360-day year, 30 days to a month, the same convention the retirement computation uses.
The calculator lines your periods up in date order and removes any gaps between them, so the service before and after a break sits side by side. It then slides a 36-month window across that joined service, totals rate times time inside each window, and keeps the highest. If you entered less than 36 months in all, the window is your whole period of service.
For part-time periods it keeps the full-time rate in the average and computes a proration factor: your hours divided by full-time hours, weighted by the length of each period. OPM applies that factor to the annuity after the formula, not to the high-3 (OPM, retrieved 2026-10-13).
A worked example
An employee earned $98,000 from January 2023, $101,500 from mid-January 2024 and $105,000 from mid-January 2025 through the end of 2026. The best 36 months run from January 2024 to December 2026: about two weeks at $98,000, a year at $101,500 and nearly two years at $105,000. Weighted by time, the average is about $103,756. The last three calendar years alone would overstate it, and a plain average of the three rates would too.
The same employee working 20 hours a week for the whole final period keeps the same high-3, because the full-time rate stays in the average. The proration factor becomes about 75 percent over the four years entered, and that factor is what OPM multiplies the annuity by.
What to do with your estimate
Carry the result into the FERS pension estimator with the link under the result, then read how the FERS annuity is calculated to see where the high-3 sits in the formula. If a period's rate looks off, check it against the GS pay tables.
FFEBA is an education organization. If you want someone to look at your own numbers, we can match you with a Federal Retirement Consultant (FRC), a professional trained on federal benefits. The FRC designation is listed with FINRA. The first review is free, nothing is booked until you choose a time, and you are never obligated to work with anyone we introduce. Get matched with an FRC.
Questions about this calculator
What counts as basic pay in a high-3?
Basic pay is your rate of pay plus locality pay, and for some employees law enforcement availability pay or special rates. Overtime, bonuses, awards, cash allowances and lump-sum leave payments do not count (OPM, retrieved 2026-10-13).
Does my high-3 have to be my last three years?
No. It is the highest average over any 36 consecutive months of service. For most people that is the last three years, because pay usually rises, but if you took a lower-paying job near the end, an earlier window can be higher. The calculator checks every window.
What if I have a break in service?
OPM closes the break and joins the service on each side, so a 36-month window can span a gap. The calculator does the same and tells you when it has done so. Time out of service is never counted in the average.
What if I have less than three years of service?
The average runs over your whole period of service instead of 36 months. The calculator says so in the result and uses every month you entered.
How does part-time work change my high-3?
For part-time service after April 6, 1986, OPM uses the full-time rate of your position in the high-3 and then multiplies your annuity by a proration factor, the hours you actually worked divided by full-time hours. Enter the full-time annual rate for each period and your hours a week; the factor appears in the result. It changes the annuity, not the high-3.
Is this the figure OPM will use?
No. This is an educational estimate on the dates and rates you enter. OPM computes the official high-3 from your pay records. Use it to check an estimate from your agency or to see what a promotion or a later date would do.
Reviewed by the FFEBA education team. Last reviewed October 2026.
Sources
- U.S. Office of Personnel Management, FERS computation, retrieved 2026-10-13
- U.S. Office of Personnel Management, CSRS and FERS Handbook, chapter 50 (computation of annuity, average pay), retrieved 2026-10-13
- U.S. Office of Personnel Management, CSRS and FERS Handbook, chapter 55 (part-time service), retrieved 2026-10-13
Every government figure on this page carries its source and retrieval date. Worked examples are educational estimates on the assumptions shown, not a projection of any person's benefit. FFEBA is an education organization, not a financial advisor.
