How to use the pension calculator
Have your latest benefit statement and plan description handy. The calculator only models the numbers you enter, so match the plan's own definitions of pay and credited service.
If your plan quotes an early retirement or survivor reduction, enter that total percentage. The calculator doesn't invent a reduction schedule, because every plan uses its own.
- Enter your current age, the age your pension starts and your credited service so far.
- Choose whether you know your final average pay or want to project current pay forward with a growth rate.
- Enter the plan's accrual multiplier and any cap on credited service.
- Add quoted early-start and survivor-option reductions, plus the survivor continuation rate.
- Set the COLA, inflation, tax share and rate, projection years and discount rate.
- Add a lump sum offer if you have one, then read your monthly pension and the comparison.
Defined benefit pension formula
The basic pension formula is pay x service x multiplier. Projected service is your current service plus the years until your pension starts, limited by any cap. If you choose to project current pay, the calculator grows it to your start age first.
Reductions are applied one after the other, not added together. The survivor payment is then a share of your reduced pension. After that, the calculator grows the pension by your COLA, shows its value after inflation and discounts it back to your start date.
Pensionable pay at start = current pay x (1 + pay growth)^years to start (if projecting)Service used = current service + years to start, up to the capFormula benefit = pensionable pay x service used x accrual multiplierYour pension = formula benefit x (1 - early-start reduction) x (1 - survivor-option reduction)Survivor payment = your pension x continuation ratePresent value = sum of each year's pension / (1 + discount rate)^year
Example: $85,000 final average pay and 32 years
A 45-year-old has 12 years of service and plans to start the pension at 65. Final average pay is $85,000 and the multiplier is 2%. By 65 they'll have 32 years, so the pension is $54,400 a year or $4,533.33 a month. That replaces 64% of pay.
A 50% survivor option would pay $27,200 a year to a surviving spouse. With a 2% COLA, the pension reaches $79,250.53 in year 20. Over those 20 years, payments add up to $1,321,776.92 before tax.
| Step | Calculation | Result |
|---|---|---|
| Service at start | 12 + 20 | 32 years |
| Formula benefit | $85,000 x 32 x 2% | $54,400 a year |
| Monthly pension | $54,400 / 12 | $4,533.33 |
| 50% survivor payment | $54,400 x 50% | $27,200 a year |
| Value of 20 years at 4% discount | Year-end present value | $875,385.78 |
Early retirement and survivor reductions
Reductions multiply rather than add up. Suppose a plan quoted a 10% early-start reduction and an 8% reduction for a survivor option. The $54,400 pension becomes $54,400 x 0.90 x 0.92 = $45,043.20 a year, or $3,753.60 a month. The 50% survivor payment would then be $22,521.60.
A survivor continuation rate isn't the same as the cut to your own check. Choosing 50% for a spouse doesn't halve your pension. PBGC lists straight life, joint and survivor, certain and continuous, and pop-up forms for the plans it runs. Ask your plan for a quote on each option you're weighing.
Pension lump sum vs monthly payments
If you're offered a lump sum, the calculator compares it with the present value of your projected payments. Using the example's 20 years, 2% COLA and a 4% discount rate, the payments are worth $875,385.78 at the start date. A $700,000 offer would be 79.96% of that. Nominal payments pass $700,000 in year 12, around age 76.
The discount rate you pick changes the answer a lot, as the table shows. This is not your plan's official lump sum formula, and it doesn't account for life expectancy. Our guide to pension lump sum vs monthly payments covers the rest of the decision.
| Discount rate | Present value of payments | Offer as share of value |
|---|---|---|
| 3% | $964,332.23 | 72.59% |
| 4% | $875,385.78 | 79.96% |
| 5% | $797,797.86 | 87.74% |
| 6% | $729,877.43 | 95.91% |
COLA, inflation and taxes
A COLA raises your payment only if your plan provides one. Without it, inflation slowly eats away at a fixed pension. At 2% inflation with no COLA, the $54,400 pension buys about what $37,341.83 buys today by year 20. With a 2% COLA, it keeps its value.
IRS Topic 410 explains that pension payments can be fully or partly taxable, depending on whether you paid in with after-tax money. The calculator only applies the taxable share and rate you enter. It doesn't work out your tax basis or brackets.
When to trust your plan over the calculator
Your plan administrator's dated estimate is the official number. Plans define pensionable pay, credited service, vesting and retirement ages in their own ways. Bonuses and overtime may not count, and breaks, leave or a plan freeze can change your service.
This calculator doesn't check vesting, PBGC guarantee limits, Social Security offsets or divorce orders. Public, military and international pensions often follow different rules. If your estimate and the plan's don't match, find the first input that differs rather than tweaking a later one.
Sources
These public references support the plan types, payment forms, survivor rules, lump sum cautions and tax notes on this page.