How to Calculate Your FERS Pension: A Step-by-Step Guide for Federal Employees

OPM processed over 31,000 federal retirement applications in February 2026 alone — another record high. Tens of thousands of federal employees are making one of the most permanent financial decisions of their lives right now. Many of them are doing it without ever seeing the actual math behind their pension number.

This post changes that. By the end, you’ll know exactly how your FERS pension is calculated, what each variable means, and — more importantly — which ones you can still influence before you retire.

The FERS Pension Formula (Straight from OPM)

According to the Office of Personnel Management, your FERS basic annuity is calculated using one of two formulas depending on your age and years of service at retirement:

Situation	Formula
Standard retirement	High-3 Average Salary × Years of Service × 1%
Age 62+ with 20+ years of service	High-3 Average Salary × Years of Service × 1.1%

That’s it. Three numbers control your entire monthly pension for the rest of your life. Let’s break each one down.

Variable #1: Your High-3 Average Salary

Your “high-3” is the average of your highest basic pay earned over any three consecutive years of federal service. For most employees, this is their final three years — but not always.

What counts toward your high-3?

Basic pay counts. This includes your base salary and locality pay. What does not count: overtime, bonuses, allowances, or any non-base compensation.

Can you increase your high-3?

Yes — and this is one of the most overlooked planning opportunities in federal retirement. A promotion, a within-grade increase, or even a step increase in your final three years directly raises your high-3 and therefore your pension for life. If you’re within three years of retirement and a promotion opportunity exists, the math almost always favors taking it.

Variable #2: Years of Creditable Service

This is your total years and months of creditable federal civilian service. It’s not just how long you’ve worked — it’s what OPM counts toward your pension.

What adds to your years of service?

• Civilian federal service — all creditable time in a federal position
• Military service — if you’ve made the military deposit (buyback), your active duty time counts
• Unused sick leave — at retirement, your unused sick leave balance is converted and added to your service time. 2,087 hours = 1 full year of additional service credit
• Part-time service — counted proportionally based on hours worked

What doesn’t count?

Periods of leave without pay (LWOP) over six months in a calendar year are typically excluded. Temporary or intermittent service may not count unless specific deposit requirements are met.

Variable #3: The Multiplier — 1% vs. 1.1%

This is where timing your retirement can make a meaningful difference. If you retire at age 62 or older with at least 20 years of service, your multiplier increases from 1% to 1.1% — a 10% boost to your entire pension, applied permanently.

On a $90,000 high-3 with 25 years of service, that difference looks like this:

Multiplier	Annual Pension	Monthly Pension	Over 20 years
1.0% (retire before 62)	$22,500	$1,875	$450,000
1.1% (retire at 62+)	$24,750	$2,063	$495,000
Difference	$2,250/yr	$188/mo	$45,000

Waiting until 62 — even just a few extra months — can be worth tens of thousands of dollars over a retirement. Whether that trade-off makes sense depends on your full financial picture, not just the pension formula.

A Full Calculation Example

Let’s make this concrete. Meet David, a GS-13 federal employee considering retirement:

• Age: 60
• Years of service: 28
• High-3 average salary: $112,000
• Unused sick leave: 1,200 hours (≈ 0.57 years additional credit)

Effective years of service: 28 + 0.57 = 28.57 years

Multiplier: 1% (he’s 60, not 62+)

Annual pension: $112,000 × 28.57 × 0.01 = $31,998/year ($2,666/month)

Now, what if David works two more years to age 62?

• Years of service: 30 (plus sick leave)
• High-3 likely increases with step increases
• Multiplier jumps to 1.1%
• Estimated pension: $112,000+ × 30+ × 0.011 = ~$37,000+/year

That’s roughly $5,000 more per year — every year — for the rest of his life. The two-year decision is worth over $100,000 over a 20-year retirement. Whether it’s the right decision for David depends on his health, TSP balance, family situation, and other factors — but he needs to see the number first.

Why Your Agency’s Estimate Might Be Off

This comes up in nearly every workshop we run. Federal employees receive a pension estimate from their agency — often through the GRB platform or a benefits statement — and assume it’s the final word. It frequently isn’t.

Common sources of error in agency estimates:

• Sick leave balance not updated to reflect current hours
• Military service credit not applied (deposit not verified)
Locality pay changes not captured in the high-3 window
• Part-time service periods calculated incorrectly
• Survivor benefit election not factored into net pension figure

The estimate is a starting point. Your actual pension is calculated by OPM after you submit your retirement package — and the interim period (called “interim pay”) can last months while OPM processes your full annuity.

What the Pension Formula Doesn’t Tell You

Your FERS pension is one of three income streams in federal retirement. The formula gives you the pension number — but your full retirement income picture includes:

• TSP — how much you’ve saved, which funds you’re in, and how you’ll withdraw it
• Social Security — when you claim determines your lifetime benefit significantly
• Special Retirement Supplement — if you retire before 62, the SRS may bridge your income gap until Social Security begins

Running just the pension formula without mapping the other two income streams gives you an incomplete — and often overly optimistic — picture of what retirement actually looks like month to month.

Three Things to Do with This Information Now

1. Pull your current benefits statement. Log into your agency’s HR portal or the GRB platform and find your most recent projected pension estimate. Compare it to the formula above using your own numbers.
2. Calculate two scenarios. Run your pension at your earliest eligible retirement date, then again 2–3 years later. The gap is almost always larger than people expect.
3. Don’t stop at the pension number. Add TSP, Social Security timing, and the SRS to get your complete monthly retirement income picture.

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Sources: OPM FERS Computation; Federal News Network, March 2026. This article is for educational purposes only and does not constitute financial, legal, or retirement advice.