Investment Annuity Calculator: Estimate Growth and Retirement Income
Use this guide to understand the assumptions, inputs, results, and next steps behind the calculator.
Created by Luis Gonzalez · Last updated October 18, 2026
A deferred annuity is an insurance contract designed to accumulate value before a future payout phase. This calculator estimates how an initial investment and annual additions might grow, then compares a modeled annuity income stream with withdrawals from a self-managed portfolio. Its results depend on the return, fees, payout rate, tax rate, and inflation assumptions you enter; they are not an insurer’s quote or a guarantee.
Use it to explore a possible income tradeoff, then compare with a retirement annuity estimate, a lifetime annuity projection, or a deferred income annuity. A contract’s actual payout depends on its terms, options, fees, and the insurer.
Enter savings, timing, and payout assumptions
The accumulation phase begins with your initial investment and adds the annual contribution once per modeled year. Enter current age and annuitization age to set the length of that phase. The calculator assumes annual contributions occur after the year’s investment growth.
The growth-rate field is the assumed gross annual return during accumulation. Annual fees are subtracted from that rate, so the default 6% growth assumption and 1.25% fee produce a modeled 4.75% net accumulation return. The payout rate then applies to the accumulated balance to estimate annual income.
The tax-rate field estimates tax on annuity income by multiplying the modeled income by one minus that rate. This is a simplified estimate. Actual taxation depends on the annuity’s tax status, the source of funds, and the distribution rules. For a comparison, the self-managed return and withdrawal-rate inputs control the alternative portfolio estimate. Inflation adjusts annuity income to show its purchasing power over time.
Defaults are $100,000 invested, $10,000 added annually, ages 45 to 65, 6% growth, 1.25% annual fees, a 5.5% payout rate, 22% tax, 2.5% inflation, and a 7% self-managed return with a 4% withdrawal rate.
Worked example: what the default projection says
With 20 years of accumulation, the calculator projects an accumulated value of $575,033. Total contributions, including the initial investment, are $300,000. Subtracting contributions from the projected balance gives $275,033 of modeled tax-deferred growth:
Total contributions = initial investment + annual additions × accumulation years
$100,000 + ($10,000 × 20) = $300,000
Tax-deferred growth = accumulated value − total contributions
$575,033 − $300,000 = $275,033
The model applies the 5.5% payout rate to the projected balance:
Annual annuity income = accumulated value × payout rate
$575,033 × 0.055 ≈ $31,627
Dividing by 12 gives approximately $2,636 per month before tax. The estimated after-tax annual amount uses the assumed 22% tax rate:
Annual after-tax income = annual annuity income × (1 − tax rate)
$31,627 × (1 − 0.22) ≈ $24,669
$24,669 ÷ 12 ≈ $2,056 per month after tax
The model’s first accumulation-year balance is $114,750: it applies 4.75% net growth to $100,000, then adds $10,000. That ordering is part of the calculator’s assumptions, not a statement about when a real contract credits interest.
Compare modeled annuity and self-managed income
At the default assumptions, the annuity estimate pays $31,627 a year before tax. The self-managed comparison begins with a withdrawal of $23,001 a year, equal to 4% of the accumulated value after rounding. The calculator reports an $8,626 annual income difference between those initial estimates.
| Scenario | Accumulated balance | Payout / withdrawal rate | Modeled first-year income |
|---|---|---|---|
| Lower annuity payout | $575,033 | 4.5% | About $25,876 |
| Default annuity payout | $575,033 | 5.5% | $31,627 |
| Higher annuity payout | $575,033 | 6.5% | About $37,377 |
| Default self-managed withdrawal | $575,033 | 4.0% | $23,001 |
The annuity payout rate is not an investment return. It is the assumed percentage of the accumulated value paid as income. A higher payout estimate can mean more income, but it may reflect different contract features or less favorable terms, such as limited or no payments to beneficiaries. Request actual illustrations that specify whether payments are fixed, inflation-adjusted, single-life, or joint-life.
The self-managed comparison is not a guaranteed alternative. It assumes a fixed annual withdrawal amount based on the original balance and applies the selected return to the remaining portfolio. The model projects self-managed depletion at age 91, just beyond its age-90 income table, while its final listed age is 90. It reports $790,675 in cumulative annuity payouts and $575,025 in self-managed payouts over the modeled period. Those totals do not have the same risk, liquidity, or bequest characteristics.
A self-managed portfolio remains under your control, but its value and income can vary. An annuity can transfer some investment or longevity risk to an insurer, depending on the contract, but may reduce liquidity and leave less money for heirs. Consider comparing the 4% rule withdrawal projection and a bucket strategy alongside annuity options.
Fees, taxes, and inflation change the comparison
Fees reduce accumulation because the calculator subtracts the annual fee rate from the gross growth rate. In the default case, 6% minus 1.25% equals 4.75%. A fee quoted by a provider may not include every expense, such as rider charges, administrative fees, or surrender charges. Read the contract schedule and ask how fees affect the guaranteed and non-guaranteed values.
The after-tax number is an estimate based on one flat rate. It does not calculate federal or state tax brackets, deductions, Social Security taxation, or the possibility that part of a nonqualified annuity payment is treated as a return of basis. Qualified annuity distributions funded with traditional retirement-account money are generally taxed as ordinary income. The IRS explains the tax treatment of annuity distributions; confirm how it applies to the particular contract and account.
Inflation also matters. The calculator estimates that the default $31,627 annual annuity income at age 65 has a real value of $19,301 in today’s dollars at the start of payouts, given 20 years of 2.5% inflation. Its annual nominal payment remains level in the modeled income phase, so its purchasing power falls over time. The calculator does not model an inflation-adjusted annuity payout option.
Understand the key contract and tax distinctions
“Tax-deferred” means tax on investment growth is generally postponed while assets remain inside the contract; it does not mean tax-free. The tax treatment depends on whether the contract is held in a qualified account such as an IRA or is purchased with after-tax money. A qualified annuity inside a traditional IRA follows IRA distribution rules as well as the annuity contract.
If an IRA or other tax-deferred account is involved, required minimum distributions may apply. The general RMD starting age is 73 under current federal rules, with the age scheduled to rise to 75 in 2033 under SECURE 2.0 for people covered by that change. An annuity held in an IRA does not automatically remove the need to meet applicable RMD requirements. See the IRS RMD overview and the guide to required minimum distributions.
Before comparing offers, identify:
- Guarantee: Is the quoted amount guaranteed, or based on current assumptions?
- Payout form: Does it cover one life, two lives, or a fixed period?
- Inflation protection: Does payment rise, and what does that option cost?
- Liquidity: Can you withdraw principal, and are there surrender charges?
- Death benefit: What, if anything, can a beneficiary receive?
- Insurer strength: What protections apply in your state if the insurer fails?
For a second view of payout mechanics, use an annuity calculator or immediate annuity calculator. If you are comparing an IRA-funded contract, the IRA annuity calculator focuses on that account context.
Formula behind the projection
The accumulation formula applies net growth and then adds the annual contribution each year. The calculator rounds the final displayed values to whole dollars.
Net annual growth rate = (gross growth rate − annual fees) ÷ 100
Balance after each accumulation year = prior balance × (1 + net annual growth rate) + annual addition
Annual annuity income = accumulated balance × payout rate ÷ 100
Estimated after-tax monthly income = annual annuity income × (1 − tax rate ÷ 100) ÷ 12
This is a deterministic projection: one assumed return each year, rather than a range of market outcomes. It does not simulate sequence-of-returns risk, contract-specific pricing, insurer crediting methods, or taxes in detail.
Frequently asked questions
Is the projected payout guaranteed?
No. The calculator applies your payout-rate assumption to an estimated future balance. Only a specific insurer illustration and contract can state what is guaranteed, subject to the contract terms and the insurer’s ability to pay claims.
Does a higher payout rate always make an annuity better?
No. A higher payment may come with fewer benefits, such as no inflation adjustment, no refund, or no continuing payment to a survivor. Compare the complete contract and not just the first-year income.
Why does the calculator show both pre-tax and after-tax income?
The pre-tax figure applies the payout percentage to the accumulated balance. The after-tax estimate applies your entered tax rate as a simple reduction. Your actual tax bill may differ because the calculator does not model tax brackets or contract basis.
Should I annuitize all of my savings or keep some invested?
That is a tradeoff between predictable income and liquidity, investment exposure, and potential inheritance. Some retirees use guaranteed income for essential expenses and retain liquid investments for flexibility, but the right mix depends on other income, expenses, health, and contract terms. Compare that approach with a retirement income projection.
Can I withdraw the money whenever I want?
Not necessarily. Access depends on the contract, withdrawal provisions, surrender-charge schedule, and account rules. A taxable distribution before age 59½ may also trigger an additional tax unless an exception applies. Ask the insurer for the withdrawal terms before purchasing.
Does the calculator account for Social Security or a pension?
No. It estimates income from the modeled annuity and self-managed investment only. Add other reliable income separately using a Social Security estimate or a pension income projection.
What should I compare before requesting an annuity quote?
Compare the same balance, purchase date, payout start date, survivor option, inflation feature, guarantee period, and tax status across offers. Ask for both guaranteed and non-guaranteed values where applicable. A retirement withdrawal strategy comparison can help frame how the annuity fits with other assets.
Use the estimate to identify questions and test assumptions, then compare actual contract illustrations before making an irreversible income decision.