Pension Lump Sum vs Annuity Calculator
Introduction: reading a pension buyout offer
When a pension plan hands you an election form, you are usually being asked to price a trade most people only face once. Keep the annuity and the plan mails you a check on a schedule for years; take the lump sum and you walk away with a single amount you now have to invest, protect, and outlive. The two paths solve different problems — one buys certainty, the other buys control — so comparing the headline numbers side by side is misleading. What makes them comparable is discounting: this tool restates the whole stream of future annuity checks in today's dollars and sets that figure next to the lump sum on the table.
Treat the answer as one input, not a verdict. Taxes, survivor coverage, the plan's funding and PBGC backing, your health and family longevity, inflation, outstanding debt, and any required spousal consent can each outweigh a few thousand dollars of present-value difference. Run the comparison to see the pure financial tradeoff, then take the plan documents and the number below to a fiduciary advisor before you sign anything irrevocable.
Formula for the annuity's present value
The calculator treats the annuity as an annual payment that may grow by a cost-of-living adjustment (COLA). If the first payment is PMT, the discount rate is r, the COLA is g, and payments last n years, the present value is:
Plain-text formula for constant annual annuity: PV = payment * (1 - (1 + r)^(-n)) / r.
Plain-text formula with growth: PV = payment * (1 - ((1 + g) / (1 + r))^n) / (r - g). If r == g, use PV = payment * n / (1 + r).
When the discount rate and COLA are equal, the formula simplifies to PMT x n / (1 + r). For a level annuity with no COLA, it becomes the standard present value of an ordinary annuity.
If you set the frequency to monthly, the calculator does not simply divide the annual rate by twelve. It converts your annual discount rate and COLA into their true monthly-compounded equivalents — the monthly rate that compounds to the annual figure over twelve periods — and then discounts each of the n × 12 payments individually. That keeps a monthly pension quote comparable to an annual one instead of overstating the effect of compounding. Enter the monthly check as the payment amount when you choose monthly; the tool handles the period count and rate conversion for you, so you never have to annualize the figure by hand.
How to use the calculator and pick each input
Enter the offer exactly as your plan states it, then match the discount rate to how you would actually put the cash to work. The inputs below are where most comparisons go wrong, so read the notes before you type.
- Lump sum offer: the gross one-time amount shown in your pension election materials.
- Annual annuity payment: the expected first-year annual payment. If the offer is monthly, multiply by 12.
- Years of payments: use a planning horizon that matches the offer. For a lifetime annuity, this is a longevity assumption, not a guarantee.
- Discount rate: the annual return you would need or reasonably expect on the lump sum after investment risk, fees, and taxes.
- COLA: the annual payment increase, if the plan provides one. Enter 0 if payments are fixed.
Worked example: a $240,000 buyout offer
Suppose the plan offers a $240,000 lump sum or $18,000 per year for 20 years, with a 3% discount rate and no COLA. Discounting each payment gives an annuity present value of about $267,800 — roughly $27,800 more than the lump sum under those assumptions. The nominal payments add up to $360,000, but because those dollars arrive over two decades, their worth today is far less than that headline total.
If you raise the discount rate, the annuity's present value falls because future payments are worth less today. If you add a COLA, the annuity's value rises because later payments grow.
Lump sum vs annuity, feature by feature
Present value settles the money question, but the two options differ on risks that never show up in a single dollar figure. The table lines up the tradeoffs most retirees weigh alongside the number this calculator produces.
| Consideration | Lump sum | Lifetime annuity |
|---|---|---|
| Longevity risk | You carry it — the money can run out if you live long or spend fast. | The plan carries it — checks continue no matter how long you live. |
| Investment control | Full control over allocation, withdrawals, and timing. | None — the payment schedule is fixed by the plan. |
| Inflation | You can invest for growth, but nothing is guaranteed. | Erodes purchasing power unless a COLA is built in. |
| Estate / heirs | Any unspent balance passes to your heirs. | Usually ends at death, or a reduced amount for a survivor. |
| Default risk | None once the cash is in your account. | Depends on plan funding; PBGC insurance caps the backstop. |
| Behavioral risk | Requires discipline to avoid overspending a large balance. | Built-in guardrail against spending down too quickly. |
When each side tends to win
The annuity usually looks stronger on this calculator when you assume a low discount rate, a long payout horizon, or a meaningful COLA — all of which push more value into future checks. It also fits people who worry about outliving their savings, dislike managing investments, or have a spouse who needs a survivor benefit. The lump sum tends to win when you can reasonably earn more than the plan's implied return, when your health or family history points to a shorter horizon, when leaving money to heirs matters, or when the plan's funding gives you pause. Because the election is normally irrevocable, run the numbers at a couple of discount rates before deciding: if the answer flips between a rate you would earn conservatively and one you would earn aggressively, the decision is really about how much investment risk you want to shoulder, not about the pension math itself.
What the result means
A positive difference means the annuity has the higher present value. A negative difference means the lump sum is larger than the discounted stream of payments. The margin matters: a small gap can be overwhelmed by taxes, investment fees, survivor protection, or personal risk preferences, while a large gap deserves closer review. The tool also reports the nominal total of all payments before discounting and the gap as a percentage of the offer, so you can gauge whether the difference is a rounding error or a decision-changing amount.
Limitations of this present-value comparison
The one number this tool produces deliberately ignores a lot. It does not model income tax on either option, the value of a joint-and-survivor benefit, the plan's funding health or PBGC insurance limits, the chance you live well past your horizon assumption, inflation beyond any COLA you enter, the fees that would drag on a rolled-over lump sum, or your own tolerance for market risk. A close call on present value can easily flip once those factors are priced in, so use the result to frame the decision rather than to settle it.