Understanding your annuity payout
The table below shows how the assumed rate of return changes the sustainable monthly payout for the same principal and payout period, since a positive return allows the balance to support a higher payout than principal divided evenly by the number of months.
| Assumed rate of return | Effect on sustainable monthly payout |
|---|---|
| 0% (no growth assumed) | Lowest payout — equals the principal divided evenly across all months, since there is no growth to supplement withdrawals |
| A positive rate | Higher payout than the 0% case, since ongoing growth on the remaining balance supplements each withdrawal |
| A higher assumed rate | Further increases the sustainable payout on paper, but overstates future certainty since market-based returns are not guaranteed |
- This calculator produces a period-certain payout: it fully exhausts the principal by the end of the stated number of years and does not continue paying beyond that date, unlike a lifetime annuity product, which continues payments for as long as the annuitant lives regardless of how long that turns out to be.
- This calculator assumes a constant rate of return throughout the payout period; actual investment returns fluctuate, so a real self-managed drawdown could exhaust funds earlier or later than this level-payout projection if actual returns differ from the assumption.
- Commercially purchased annuity contracts include insurer-specific fees, guarantees, surrender charges and mortality-based pricing (for lifetime annuities) that this calculator does not model; a specific annuity product's illustration from a licensed provider is the authoritative source for its actual terms.
What is an annuity payout calculation?
An annuity payout calculation determines the level periodic payment that a fixed starting principal can support over a set number of years, assuming the remaining balance continues earning a stated rate of return and the payments are structured to bring the balance to exactly zero by the end of the period. This is the reverse of an accumulation calculation, which instead projects how regular contributions grow into a future lump sum.
This structure — sometimes called a period-certain payout or a self-amortizing withdrawal schedule — is used both in commercial annuity products, which the Financial Industry Regulatory Authority (FINRA) and SEC describe as insurance contracts that convert a lump sum into a stream of income, and more generally as a planning calculation for any lump sum a person wants to draw down evenly over a defined number of years.
This calculator assumes the payout amount and the rate of return remain constant for the entire period; it does not model inflation adjustments to the payment, changes in the rate of return over time, or the specific fees, guarantees and insurance-company-specific terms found in an actual purchased annuity product.
How to use this annuity payout calculator
- Enter the starting principal (lump sum) available.
- Enter the expected annual rate of return the remaining balance will earn during the payout period.
- Enter the number of years over which the principal should be paid out.
- Read the level monthly payout, the equivalent annual payout, and the total amount paid out over the full period.
The formula behind the level payout
The calculation uses the standard formula for the payment on a fully amortizing annuity: it solves for the level monthly payment that, combined with ongoing growth on the remaining balance at the stated rate, reduces the principal to exactly zero after the specified number of months.
On the calculator's default example — a $500,000 principal at a 5% annual rate over 25 years (300 months) — the monthly payout is $2,922.95, an annual payout of $35,075.40, with a total of $876,885.06 paid out over the full 25-year period (the excess over the original $500,000 principal representing ongoing investment growth during the payout period).
Common mistakes
- Assuming this calculator models a lifetime annuity — it computes a period-certain payout that exhausts the principal by a specific end date, not a payout that continues for as long as the recipient lives, which is how many commercial annuity products are structured.
- Using an unrealistically high assumed rate of return, which inflates the projected sustainable payout beyond what a real, lower or more volatile return would actually support.
- Forgetting that this calculator assumes a level, unadjusted monthly payout for the entire period, when many retirees plan to increase withdrawals over time to keep pace with inflation.
- Confusing this payout calculator with a retirement withdrawal calculator that models an inflation-adjusted withdrawal amount against a balance that may or may not last a specific number of years — the two use different assumptions and answer different questions.
- Not accounting for taxes on the payout, which this calculator does not model and which depend on the specific account type and tax treatment of the underlying funds.
Preguntas frecuentes
How much monthly income can $500,000 provide over 25 years?
At an assumed 5% annual rate of return, a $500,000 principal can support a level monthly payout of $2,922.95 for 25 years (300 months), fully exhausting the principal by the end of that period, with $876,885.06 paid out in total.
Does this calculator model a lifetime annuity?
No. This calculator computes a period-certain payout that fully exhausts the principal by a specific end date you choose. A lifetime annuity, sold as an insurance product, instead continues paying for as long as the annuitant lives, which involves insurer-specific mortality pricing this calculator does not model.
Why does a higher assumed rate of return increase the sustainable payout?
As the principal pays out over time, the remaining balance continues earning the assumed rate of return, which supplements each withdrawal. A higher assumed rate means more of each payout comes from ongoing growth rather than from drawing down the original principal, allowing a higher level payout to still reach exactly zero by the end of the period.
Does the payout amount increase with inflation over time?
No. This calculator computes a single level (unchanging) monthly payout for the entire period. It does not model inflation adjustments to the payment amount; a retirement withdrawal calculator that explicitly models an inflation-adjusted withdrawal is a better fit for that specific question.
Is this the same as buying an annuity from an insurance company?
No. This calculator performs a mathematical projection based on the principal, assumed rate of return, and payout period entered. An actual commercial annuity purchased from an insurance company includes specific fees, guarantees, surrender charges, and (for lifetime annuities) mortality-based pricing that this general calculator does not model.
Referencias
- Financial Industry Regulatory Authority (FINRA). Annuities: how they work and what to consider. finra.org.
- U.S. Securities and Exchange Commission (SEC), Investor.gov. Annuities overview and investor bulletins. investor.gov.
- Brealey RA, Myers SC, Allen F. Principles of Corporate Finance (13th ed.). McGraw-Hill, 2020. Chapter 2: How to Calculate Present Values (annuity formulas).