Annuity Calculator
Grow a balance into an annuity, or convert a lump sum into fixed monthly income.
Lump sum to start with
Fixed annuity rates ≈ 4–6%
How long the money grows
Adjusts to today's money — US avg ~2–3%
Value Built Up
$476,781
≈ $476.78K
≈ $290,966 in today's money
Total Deposited
$220,000
$100,000 start + contributions
Interest Earned
$256,781
Growth on your money
Interest added $256,781 — that's 1.2× growth on every dollar you put in.
Balance Growing Over 20 Years
📊 Year-by-Year Breakdown
Deferred-annuity mode grows a lump sum plus monthly contributions at a fixed rate. Real annuity products carry fees this estimate does not model. The inflation-adjusted figure shows the result in today's purchasing power.
How to use this calculator
- Choose a mode — Grow a Balance (accumulation) or Convert to Income (payout).
- Grow a Balance: enter your starting amount, annual rate, years, and monthly contribution.
- Convert to Income: enter the lump sum, annual rate, and the payout period.
The result updates instantly — either the value built up, or the fixed monthly income.
How it works
An annuity is about moving between a lump sum and a stream of payments, and this calculator handles both directions.
- Accumulation grows a starting amount plus monthly contributions at a fixed rate — the standard future-value-of-an-annuity calculation.
- Payout does the reverse: it finds the fixed monthly payment that will exhaust a lump sum over the chosen term, with the remaining balance still earning the rate. This is the same formula a loan uses, applied to paying a balance out to yourself.
The result also separates the interest from the money you contributed or were paid, so you can see how much of the outcome is growth.
Things to know
This calculator shows the financial maths of an annuity, not the terms of a specific product. Real annuities sold by insurers add fees, surrender charges and guarantees that change the picture. Use these figures to understand the underlying numbers and to compare scenarios, and review any actual contract — or speak to an advisor — before committing.
Frequently Asked Questions
What are the modes of this annuity calculator? ▾
Three. Grow (Deferred) is the accumulation phase — a lump sum plus optional monthly contributions grow at a fixed rate. Income (Immediate) is the payout phase — a lump sum becomes a fixed monthly income that exhausts the balance over a chosen term. How Long Will It Last? works the payout backwards: enter a lump sum and a target monthly income, and it tells you how many years the money lasts. 'Deferred' and 'immediate' are the standard industry terms for these two annuity types.
What is the difference between a deferred and an immediate annuity? ▾
A deferred annuity is in the accumulation phase — money is paid in and grows, with payouts deferred to a later date. An immediate annuity is already in the payout phase — a lump sum is converted into income that starts right away. This calculator's Grow mode models a deferred annuity; its Income mode models an immediate one.
How is the monthly payout calculated? ▾
Payout mode uses the standard annuity payment formula: the monthly payment that fully exhausts the principal over the term, while the remaining balance keeps earning the rate. A higher rate or a longer term means a different monthly figure. It is the same maths a loan uses, run in the opposite direction — instead of paying off a debt, you are paying out a balance to yourself.
What is the difference between an annuity and a savings account? ▾
An annuity is structured around converting between a lump sum and a stream of payments — either building one up or drawing one down over a defined term. A savings account is open-ended. This calculator models the cash-flow maths of an annuity; an actual annuity product from an insurer also carries fees, surrender terms and guarantees this estimate does not include.
Does this include annuity fees or insurer terms? ▾
No. The calculator shows the pure financial maths — how a balance grows, or how a lump sum converts into payments at a given rate. Real annuity contracts from insurance companies add fees, commissions, surrender charges and rate guarantees that vary by product. Use this for the underlying numbers, and read any real contract carefully.
What rate should I use? ▾
Use the rate the annuity or investment is expected to earn. For accumulation that is your expected investment return; for a payout annuity it is the rate the insurer credits the remaining balance. Lower, conservative rates give a more cautious estimate — it is worth checking a range.