How much will $1,000 a month be worth in 15 years?

Investing $1,000 a month for 15 years means paying in $180,000 in total. At a hypothetical 7% annual return it would grow to $311,105: $180,000 from your contributions and $131,105 from investment growth. At 4% the balance would be $244,657 ($64,657 of growth), and at 10% it would be $398,444 ($218,444 of growth).

At 4% a year

$244,657

$64,657 of that is growth

At 7% a year

$311,105

$131,105 of that is growth

At 10% a year

$398,444

$218,444 of that is growth

4%, 7% and 10% are example rates, not forecasts. Real returns change from year to year and are never guaranteed, and these figures leave out fees, taxes and inflation.

$1,000 a month for 15 years at different rates of return

Annual return	Final balance	Total contributed	Interest earned
1%	$194,046	$180,000	$14,046
2%	$209,416	$180,000	$29,416
3%	$226,239	$180,000	$46,239
4%	$244,657	$180,000	$64,657
5%	$264,825	$180,000	$84,825
6%	$286,912	$180,000	$106,912
7%	$311,105	$180,000	$131,105
8%	$337,606	$180,000	$157,606
9%	$366,639	$180,000	$186,639
10%	$398,444	$180,000	$218,444
11%	$433,287	$180,000	$253,287
12%	$471,458	$180,000	$291,458

Assumes no starting balance, a contribution at the end of every month, and a constant rate compounded once a year (an effective annual rate). You pay in $180,000 in every row; only the growth changes, from $14,046 at 1% to $291,458 at 12%.

Try your own numbers

The calculator starts with this example at 7%. Change the amount, rate or time period, add a starting balance, or switch the compounding, and the result updates as you type.

Balance after 15 years

$311,105

42.1% of that is interest. Your balance is 1.73 times what you put in.

Total contributions

$180,000

Interest earned

$131,105

Growth by year

Contributions
Interest

Year-by-year breakdown

Year	Contributions	Interest	Balance
1	$12,000	$380	$12,380
2	$24,000	$1,627	$25,627
3	$36,000	$3,801	$39,801
4	$48,000	$6,968	$54,968
5	$60,000	$11,196	$71,196
6	$72,000	$16,560	$88,560
7	$84,000	$23,139	$107,139
8	$96,000	$31,019	$127,019
9	$108,000	$40,291	$148,291
10	$120,000	$51,052	$171,052
11	$132,000	$63,406	$195,406
12	$144,000	$77,464	$221,464
13	$156,000	$93,347	$249,347
14	$168,000	$111,182	$279,182
15	$180,000	$131,105	$311,105

How much is your money and how much is growth?

At 7%, 15 years is not long enough for growth to overtake what you pay in: growth is 42% of the final balance and the other 58% is your own money. Keep contributing at the same pace and growth would pass contributions during year 19. The rate matters a lot here: growth overtakes contributions in year 14 at 10%, while at 4% it would take until year 33, after this 15-year period ends.

In year 15 alone, the balance earns $19,923 at 7%. That is more than the $12,000 you add that year, and compares with $380 of growth in year 1.

What if you change the plan?

Each row changes one thing and keeps everything else the same, at the 7% example rate. The comparison is with $1,000 a month for 15 years, which ends at $311,105.

Change	Final balance	Difference
Keep contributing for 5 more years (20 years in total)	$507,536	+$196,432
Start 5 years later (contribute for 10 years)	$171,052	−$140,053
Contribute $1,500 a month instead of $1,000	$466,657	+$155,552
Start with $10,000 already invested	$338,695	+$27,590
Contribute at the start of each month instead of the end	$312,864	+$1,759
Earn 6% a year instead of 7%	$286,912	−$24,193

Starting 5 years later means paying in $60,000 less, but the final balance is $140,053 lower. The gap is bigger than the missing contributions because the earliest payments are the ones with the longest time to grow. A return that is one point lower leaves you with $24,193 less after 15 years, which is roughly what a 1% annual fee would cost.

Working backwards: to reach $500,000 in 15 years at 7%, starting from zero, you would need to invest about $1,607 a month.

When would the balance reach $500,000?

The table shows the year in which the balance first reaches each amount, assuming the same $1,000 a month continues for as long as it takes. Years in bold fall within this page's 15-year period.

Balance reaches	At 4%	At 7%	At 10%
$25,000	Year 3	Year 2	Year 2
$50,000	Year 4	Year 4	Year 4
$100,000	Year 8	Year 7	Year 7
$250,000	Year 16	Year 14	Year 12
$500,000	Year 25	Year 20	Year 17

How this is calculated

The rate is treated as an effective annual rate, so the balance grows by exactly 7% over a full year. The monthly rate that compounds to 7% a year is:

Monthly rate = (1 + 0.07)^1/12 − 1 = 0.5654%

With $1,000 added at the end of each month for 180 months (15 × 12), the contributions grow to:

Balance = 1,000 × [1.005654¹⁸⁰ − 1] ÷ 0.005654 ≈ $311,105

The rates shown here are rounded; the result uses full precision. Of that balance, 1,000 × 180 = $180,000 is your contributions and the remaining $131,105 is growth. Every other row in the rate table uses the same formula with a different annual rate. The compound interest calculator page explains the formulas in more detail.

Frequently asked questions

How much interest will $1,000 a month earn in 15 years?

It depends on the rate of return. At a constant 7% a year, $1,000 a month for 15 years earns $131,105 on top of $180,000 in contributions, for a balance of $311,105. At 4% the growth is $64,657, and at 10% it is $218,444. These rates are examples, not predictions.

How long does it take to reach $500,000 investing $1,000 a month?

With a constant 7% annual return and no starting balance, the balance passes $500,000 during year 20. For comparison, at 10% it takes until year 17, and at 4% it takes until year 25.

How much do I need to invest each month to have $500,000 in 15 years?

At a constant 7% annual return you would need about $1,607 a month for 15 years, starting from zero. At 4% you would need about $2,044 a month, and at 10% about $1,255 a month.

$1,000 a month over other periods

Other monthly amounts for 15 years

A single lump sum for 15 years

See all compound interest examples in one table, or start from scratch with the compound interest calculator.