Annuity Calculator – Turn a Corpus into Monthly Income
Use this annuity calculator to estimate the fixed monthly income you could draw from a lump sum over a chosen number of years. Enter your corpus, expected annual return and payout period. The tool shows the monthly payment, total payouts and total interest or growth so you can explore retirement income or other regular withdrawal plans.
Annuity Payout Calculator
Estimate the fixed monthly income you could draw from a corpus over a chosen number of years at a constant annual return. This is useful for planning retirement income or other regular payouts.
How the annuity payout formula works
Mathematically, an annuity payout is the reverse of building a corpus with monthly contributions. Instead of asking “If I invest this much every month, what will I have?”, we ask “If I already have a corpus of this size, how much can I withdraw each month so that it lasts for a certain number of years?” The calculator models this as the present value of an annuity, where the present value is your corpus and the unknown is the payment.
With monthly compounding, the formula for the payment is:
Monthly payout = PV × r ÷ (1 − (1 + r)−n)
- PV = corpus or principal amount
- r = monthly rate (annual expected return ÷ 12 ÷ 100)
- n = total number of months (years × 12)
The calculator then multiplies the monthly payout by the number of months to find total payouts, and subtracts the original corpus to estimate total interest or growth. If you set the interest rate to zero, the formula simplifies to corpus ÷ number of months, which represents spending the entire amount evenly with no return.
Using annuity-style projections in retirement planning
A common question near retirement is “If I have this much saved, how long will it last?” or “What monthly income can I safely draw?” This annuity calculator gives you a structured way to explore that question. By entering a corpus, return assumption and payout period, you see a level monthly income that exactly consumes the corpus (plus assumed growth) over that time. While real life is rarely that tidy, the exercise clarifies the relationship between nest egg size, drawdown rate and longevity risk.
One approach is to start with your desired retirement income and work backwards. Use our Retirement Calculator to estimate how much you might need each month in retirement and how large a corpus you may build. Then plug the corpus into this annuity calculator with a payout period that reflects your planning horizon—often 20–30 years. If the resulting monthly payout is lower than your target spending, it suggests that you may need a larger corpus, a longer working life, lower spending, or a strategy that allows variable rather than fixed withdrawals.
You can also explore safety margins. For instance, try running the calculation at a slightly higher and slightly lower interest rate to see how sensitive your plan is to returns. If a small reduction in assumed return causes a sharp drop in monthly income, your plan may be too dependent on optimistic market performance. In that case, you might aim to save more before retirement, extend the payout period, hold more in stable instruments or combine guaranteed income products with market-linked investments.
Inflation is another crucial factor. A fixed nominal payout loses purchasing power over a long retirement, especially if inflation is high. Many retirees prefer a strategy where withdrawals grow gradually each year rather than staying flat, which this simple calculator does not model directly. You can approximate the effect by reducing your target payout in today’s money or by using our Inflation Calculator to test how far a fixed amount stretches in the future. In practice, a mix of annuity-style income, flexible withdrawals from growth assets and emergency reserves often works better than relying on a single rigid rule.
Finally, remember that retirement planning is about balancing security and flexibility. Guaranteed annuity products can provide peace of mind but may lock in interest rates and limit access to your capital. Market-linked drawdown strategies offer more flexibility and potential upside but also more risk. This calculator does not recommend specific products; instead, it shows how different payout assumptions translate into monthly income from a corpus. You can take these numbers into conversations with a financial planner or use them alongside other tools on this site—such as our Net Worth Calculator and Investment Calculator —to create a retirement plan that fits your goals and comfort with risk.
As with all tools on this site, the annuity calculator is for education and planning only. It does not account for individual product fees, taxes or regulatory rules in your country. Use it to build intuition, compare scenarios and ask better questions—but always pair it with personalised advice before committing your life savings to any one strategy.