Annuity Calculator

A $250,000 pot at 4% drawn down over 25 years pays $1,319.59 a month. Save $500 a month at 6% for 20 years and you finish with $231,020.45. Those are two different questions that both get called "annuity", and most free calculators answer one of them and send you somewhere else for the other.

You get both here. Flip between Grow mode and Payout mode at the top, and the numbers move as you type. Nothing you enter is uploaded, there's no account, and once the page is open nothing more gets fetched.

1. Pick a mode. Grow turns contributions into a future value. Payout turns a lump sum into a fixed monthly income.
2. In Grow mode, enter a starting balance if you have one, your contribution, whether it lands monthly or yearly, an annual rate, and the years you'll save. In Payout mode, enter the lump sum, the rate, and how long you want the income to last.
3. Set the payment timing. "End (ordinary)" is a standard annuity. "Start (due)" pays at the beginning of each period instead.
4. Read the panel. Grow shows the future value, what you put in, and the growth on top. Payout shows the monthly and yearly income, the total collected, and the interest the balance earned while it drained.
5. In Grow mode, press "Turn this into income" to carry the pot you built into Payout mode.
6. Open the year-by-year schedule to watch the balance climb or drain, download it as a CSV, or copy a link that reopens the page with your numbers already in it.

Same rate, same term, four different pots. This is what the panel prints at 4% over 25 years.

Lump sum	Monthly	Yearly	Total collected
$100,000	$527.84	$6,334.08	$158,352.00
$250,000	$1,319.59	$15,835.08	$395,877.00
$500,000	$2,639.18	$31,670.16	$791,754.00
$1,000,000	$5,278.37	$63,340.44	$1,583,511.00

The total collected is the line people read twice. A $250,000 pot hands back $395,877.00 across those 25 years, and $145,877.00 of that is interest. Money you have not withdrawn yet is still invested, so the balance keeps earning the whole time you are spending it.

Your assumed rate moves the answer more than the size of the pot does, proportionally. On the same $250,000 over 25 years, the four presets give $1,185.53 at 3%, $1,319.59 at 4%, $1,461.48 at 5% and $1,610.75 at 6%. Three points of return is worth $425.22 a month on money you already have.

One oddity worth knowing if you check our arithmetic against your own. Doubling the pot does not exactly double the payment. $100,000 pays $527.84 and $200,000 pays $1,055.67, which is a cent under double, because the payment is rounded to a whole cent before anything else is worked out from it. At a million the gap is three cents. Small, but it is there, and it is there on purpose.

Every annuity pitch says compounding does the work. Run real numbers and it takes longer to show up than the pitch suggests.

Here is the first year in which growth is worth more than everything you contributed, saving $500 a month from zero:

Rate	Growth passes contributions in
3%	year 43
4%	year 32
5%	year 26
6%	year 22
7%	year 19
8%	year 16

Twenty years at 6% reaches $231,020.45, made of $120,000.00 you paid in and $111,020.45 of growth. Your own money is still ahead there, and it stays ahead until year 22. Give it ten more years and the balance shifts hard, since 30 years at that rate reaches $502,257.52 with $322,257.52 of it growth.

Contribution timing is worth more than it looks. $500 every month and $6,000 once a year are the same money going in, but at 6% over 20 years the monthly version finishes at $231,020.45 and the yearly version at $224,736.03. That is $6,284.42 for nothing except paying earlier in the year. At 9% the same swap is worth $13,552.18.

The timing toggle is the piece most free tools leave out. It does move the number, though not by as much as the textbooks lead you to expect.

On the defaults, the ordinary setting pays at the end of each period and grows to $231,020.45. An annuity due puts each deposit in at the start instead, and the same 20 years reach $232,175.55. The $1,155.10 between them is the extra month of compounding every deposit picks up.

Payout mode moves the opposite way. The same $250,000 at 4% over 25 years pays $1,319.59 a month as an ordinary annuity and $1,315.21 as an annuity due, so being paid earlier costs you $4.38 a month.

The part we did not expect is that the size of the pot and the length of the term make no difference to how big that gap is. As a share of the payment it is just your annual rate divided by 12. We ran 500 combinations of rate, pot size and term through it, and the gap never drifted further than 0.008 of a percentage point from that. On the default $250,000 over 25 years, the toggle is worth $2.96 a month at 3%, $4.38 at 4%, $6.07 at 5% and $8.01 at 6%.

At a 0% rate it does nothing whatsoever. Both settings print $833.33, because there is no interest for the extra period to earn and so nothing for the timing to change.

If you are checking a contract you have actually been sent, match this toggle to how that contract pays rather than guessing at it.

Open the schedule on the default payout and the final year does not read zero. It reads $1, and the downloaded CSV is more specific than the table is: 25,395877.00,1.06.

That is not a display problem, it is what happens when a payment has to land on a whole cent. Three hundred identical checks rarely divide a pot exactly. We ran 1,560 payouts through the calculator, every half point of rate from 0.5% to 10%, terms from 5 to 30 years, across three pot sizes. 784 of them, just over half, finish with money still sitting in the account. The biggest leftover was $9.48.

A 0% rate shows the mechanism cleanly. $250,000 over 300 months is $833.33 a month, and 300 of those come to $249,999.00. The tool reports the difference as interest earned of minus $1.00, which is arithmetically right and still looks peculiar the first time you see it.

The same floor bites at the other end of the scale. A $1 lump sum over 25 years pays $0.01 a month, since a cent is the smallest payment there is, and 300 of those add up to $3.00 out of a $1 pot. Nobody is retiring on a dollar, but that is the sort of thing you only turn up by pushing a tool to its edges instead of trusting it, which is why it gets a mention here.

Everything else on the panel reconciles exactly, and we checked rather than assumed. Across 120 payout combinations, monthly income times the number of months equaled total paid out every single time, and the yearly figure was 12 times the monthly figure in all of them. On the growth side, future value minus contributions equaled growth across 72 runs.

Real annuities chain the two phases together. You pay in for years, then the pot pays you back, which is a deferred annuity in plain words. No free single-page tool we found joins those up, so that button is the reason this page exists in one piece instead of two.

Build something in Grow mode, then press "Turn this into income". The default $231,020.45 lands in Payout mode and pays $1,219.41 a month over 25 years at 4%, for $365,823.00 collected in total. From there you can drop the payout rate, since money in the drawdown phase usually sits somewhere more conservative than money still growing.

The button rounds to whole dollars on the way across, so $231,020.45 arrives as $231,020 and those 45 cents are gone. It changes nothing about a projection, but if you are reconciling to the penny, that is where they went.

None of this is a quote. Insurers price in mortality, fees, guarantees and their own margin, so an actual contract will come out different. What you get here is the clean underlying math, which is the number worth holding a sales pitch up against.