Annuity Payout Calculator

Using an Annuity to Convert Retirement Savings Into Steady Income

An annuity is a financial arrangement that converts a lump sum of money into a series of regular payments over a specified period. In retirement planning, annuities are used to solve one of the most challenging problems: ensuring your money lasts as long as you live. By depositing a sum with an insurance company or drawing from a retirement fund using an annuity payout formula, you can receive a predictable monthly income for the rest of your retirement without the risk of outliving your savings.

This calculator models the payout phase of an annuity. You enter the amount you have accumulated, the interest rate that the fund continues to earn while paying out, and the number of years you want the payments to last. The calculator then solves for the level monthly payment that will exactly exhaust the fund over that period. This is the standard present value of an annuity formula used by actuaries, financial planners, and retirement calculators worldwide.

The interest rate assumption is important. If your retirement fund is invested in a balanced portfolio earning around 5% per year while you are drawing it down, your monthly payments can be significantly higher than if the money sits in a low-yield savings account earning 1%. The higher the rate the fund earns during payout, the more you receive each month without running out of money sooner.

Fixed Annuities vs Self-Managed Drawdown

There are two broad approaches to converting retirement savings into income. The first is purchasing a fixed annuity from an insurance company. You hand over your lump sum and the insurer promises to pay you a fixed monthly amount for a specified term or for life. The insurer takes on the investment and longevity risk. The payout rate reflects current interest rates at the time of purchase, the insurer's costs, and profit margin.

The second approach is self-managed drawdown, where you keep your retirement fund invested and withdraw a calculated amount each month. This is what this calculator models. In a self-managed drawdown, you maintain control of your capital and can adjust withdrawals if needed, but you also bear the investment risk. If your fund earns less than assumed, it may run out before the planned end date. If it earns more, you may have money left over for your estate.

The famous 4% rule is a simplified version of this concept. Research suggested that a retiree could withdraw 4% of their portfolio value in the first year of retirement, increase that amount with inflation each year, and have a very high probability of the portfolio lasting 30 years. The rule was derived from historical US stock and bond market data and may not hold in all economic environments, but it remains a widely cited benchmark for retirement planning.

Planning for Longevity and Inflation

The biggest risk in retirement income planning is longevity. If you plan for a 20-year payout period but live for 30 years, you could exhaust your funds a decade before you pass away. Many financial planners recommend planning for at least 25 to 30 years of retirement income, especially if you retire in your early sixties or have a family history of longevity.

Inflation is the second major risk. A fixed monthly payment that is comfortable today will buy significantly less in 20 years. At a 3% annual inflation rate, a $3,000 monthly payment in today's dollars is worth only about $1,660 in real terms after 20 years. Some annuities offer inflation-adjusted payouts that increase each year, though these typically start at a lower initial amount to compensate for the rising payments.

Social Security or state pension income can partially offset both these risks by providing a baseline income that never runs out. By combining a government pension with an annuity or drawdown strategy from your personal savings, you create a layered income structure that is more robust than relying on any single source. Use this calculator to see how different scenarios play out and how adjusting the interest rate, term, or lump sum changes your monthly payout.