10-Year Annuity Calculator

What a 10-year annuity means in everyday money

Ten years of equal deposits on a fixed schedule is an annuity in the plain sense of the word. An automatic transfer of 400 dollars every month, a payroll deduction that repeats each pay period, or a series of purchase payments into an insurance contract all work the same way on paper: the amount stays level and the gap between deposits stays level.

The useful part is predictability. With three facts, the deposit, the annual rate and the number of months, the ending balance is fixed by arithmetic, and nothing has to be guessed beyond the rate itself. That is what the calculator above does, and it takes seconds.

Insurance companies also sell a product called an annuity, where a decade of deposits forms the accumulation phase of a deferred annuity and income payments come after. The SEC investor.gov annuities page (Securities and Exchange Commission, 2026) explains the contract side, including fees and surrender charges.

One timing choice changes every number on this page. An ordinary annuity deposits at the end of each month. An annuity due deposits at the start. The second version always finishes ahead, and the size of the gap is predictable too.

The future value formula, piece by piece

The future value of a level payment stream is FV = PMT x (((1 + r)^n - 1) / r). Three symbols do all the work.

• PMT is the deposit each period, 400 dollars a month in the default example.
• r is the rate for one period, not for a year. A 5 percent annual rate split across months gives 0.05 / 12 = 0.004167.
• n is the number of deposits. Ten years of monthly deposits is 12 x 10 = 120.

The formula adds up every deposit with its own growth time. The first deposit compounds for 119 months, the second for 118, and the last one earns nothing because it lands at the end of month 120. Summing those 120 terms collapses into the single expression above.

Run the pieces for the default inputs. The growth factor is (1.0041667)^120 = 1.64701, so the bracket is (1.64701 - 1) / 0.004167 = 155.28. That bracket is the multiplier on each dollar of monthly deposit: one dollar a month for 120 months becomes 155.28 dollars, of which 35.28 is interest. Multiply by 400 and the balance is 400 x 155.28 = 62,112.91.

Worked example: $400 a month at 5 percent for 10 years

A saver sets an automatic transfer of 400 dollars for the last day of every month, into an account earning 5 percent a year, compounded monthly. After 120 deposits the balance is 62,112.91 dollars. The deposits total 48,000 dollars, and the interest is 62,112.91 - 48,000 = 14,112.91, about 23 percent of the final balance.

The path to that number is not a straight line. In year 1 the account earns 111.54 dollars on 4,800 deposited. In year 10 the same deposits earn 2,895.63, roughly twenty-six times as much. The table shows the balance at even-year marks.

Halfway through the decade, at month 60, the balance is 27,202.43 dollars. The remaining five years add 34,910.48 to the balance while adding only 24,000 of deposits. Compounding does the heavier lifting late, which is also why quitting at year 7 costs more than quitting at year 3.

Deposits at the start of the month instead of the end

Move each deposit to the first day of the month and every one of the 120 payments gains one extra month of growth. The adjustment is a single multiplication: annuity due value = ordinary value x (1 + r). At the monthly rate of 0.004167, the 62,112.91 balance becomes 62,112.91 x 1.0041667 = 62,371.72, a gain of 258.80.

The gain looks small because one month of interest is small. Over a decade it is free money for moving a transfer date, and it scales with the deposit.

Which convention applies depends on the account. A transfer scheduled on payday usually lands at the end of a pay period, closer to an ordinary annuity. A commitment due on the first of the month looks like an annuity due. When a plan document quotes a projection, check which timing it assumed before comparing totals.

Monthly deposits versus one deposit a year

Some savers fund once a year instead of twelve times, and the arithmetic difference is larger than most people expect. A single 4,800 dollar deposit each December, at the same 5 percent, compounds with the annual formula FV = PMT x ((1.05^10 - 1) / 0.05) and ends at 60,373.88 dollars. The same 48,000 total, spread across months, ends at 62,112.91. The gap is 1,739.03, and it comes from timing alone: the January through November deposits sit in the account months earlier.

Deposit at the start of each year instead and the annual stream ends at 63,392.58, which beats the monthly end-of-month plan by 1,279.67. Timing on both sides matters more than savers tend to guess.

The same logic runs in reverse when the money leaves. A withdrawal taken days earlier forgoes a full period of growth, so payment timing is worth checking on both the saving side and the payout side of any plan.

What the rate does over a decade

The deposit size and the rate do not move the outcome with equal force. Doubling the deposit doubles the balance exactly, because the formula multiplies. The rate works through the growth factor, and over only 120 months its effect is moderate.

Going from 3 percent to 7 percent, a four point jump, adds 13,337.36 to the ending balance. That is real money, but compare it with raising the deposit from 400 to 800 dollars a month, which adds another 62,112.91 at any rate. Over a 10-year window, the amount saved matters more than the rate hunted for.

Time is the third lever. Extending the same 400 dollar plan from 10 years to 20 at 5 percent lifts the balance to 164,413.47, which is 2.65 times the 10-year figure rather than twice it. The later deposits rest on a larger base, so each added year contributes more than the last.

Deferred annuities and the accumulation phase

The insurance version of this math has its own vocabulary. A deferred annuity takes one payment or a series of them, lets the money grow, and starts income payments later. The growth window is the accumulation phase, and the income window is the payout phase. On a 10-year plan, the decade of deposits is the entire accumulation phase.

Growth inside the contract is tax-deferred: interest and gains are not taxed until money comes out, per the SEC investor.gov annuities page (Securities and Exchange Commission, 2026). Deferral does not erase tax, it postpones it, and withdrawn gains are taxed as ordinary income rather than at capital gains rates.

One warning from the same source belongs here. Inside a 401(k) or an IRA the money is already tax-sheltered, so an annuity wrapper adds no second layer of tax benefit. The IRS 403(b) tax-sheltered annuity page (Internal Revenue Service, 2026) covers the employer-plan version, where the word annuity refers to the payment schedule rather than an insurance wrapper.

Contracts also carry costs the plain arithmetic on this page ignores: surrender charges in the early years, mortality and expense charges, and rider fees. A 10-year projection that skips a 1.3 percent annual contract fee overstates the outcome by a wide margin, so read the fee table before trusting any projection, including this one.

What the stream is worth today, and what the tool leaves out

Present value runs the same math backwards. Suppose someone promises 600 dollars a month for 10 years and offers a lump sum today instead. At a 5 percent discount rate, PV = PMT x (1 - (1 + r)^-n) / r gives 600 x 94.28135 = 56,568.81. The payments add to 72,000, so the other 15,431.19 is interest the lump sum would earn while it waits. A lump sum offer below 56,568.81 favors the payer; one above it favors the receiver.

Four things the calculator above does not model deserve a mention.

• Taxes. Interest in a taxable account is taxed as it is earned. The balance shown is before any tax.
• Moving rates. A level 5 percent is an assumption for illustration, not a quote. Contract rates credited by insurers can change.
• Fees. Insurance wrappers charge in layers, as the accumulation phase section notes.
• Inflation. At 3 percent inflation, 62,112.91 dollars in 10 years buys roughly what 46,217.84 buys now.

A workable habit is to rerun the plan at a rate one or two points lower than hoped. If the plan still works at 3 percent, a weak decade will not sink it. This page does arithmetic, not investment advice, and it cannot pick an account or a contract for you.