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What is $1,000 at 8% worth after 30 years?

$1,000 at 8% a year, compounded monthly, grows to $10,936 in 30 years: $1,000 paid in and $9,936 of interest.

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The numbers for these inputs

YearTotal paid inInterest so farBalance
1$1,000$83$1,083
2$1,000$173$1,173
3$1,000$270$1,270
4$1,000$376$1,376
5$1,000$490$1,490
6$1,000$614$1,614
7$1,000$747$1,747
8$1,000$892$1,892
9$1,000$1,050$2,050
10$1,000$1,220$2,220
11$1,000$1,404$2,404
12$1,000$1,603$2,603
13$1,000$1,819$2,819
14$1,000$2,053$3,053
15$1,000$2,307$3,307
16$1,000$2,581$3,581
17$1,000$2,879$3,879
18$1,000$3,201$4,201
19$1,000$3,549$4,549
20$1,000$3,927$4,927
21$1,000$4,336$5,336
22$1,000$4,779$5,779
23$1,000$5,258$6,258
24$1,000$5,778$6,778
25$1,000$6,340$7,340
26$1,000$6,949$7,949
27$1,000$7,609$8,609
28$1,000$8,324$9,324
29$1,000$9,098$10,098
30$1,000$9,936$10,936

How it works

Each month the balance earns interest at one twelfth of the yearly rate, and that interest is added to the balance, so next month's interest is paid on a slightly larger amount. Any monthly deposit is added at the end of the month.

In short: new balance = old balance x (1 + rate / 12) + deposit, repeated once per month for the number of years you choose. The table shows the balance at the end of each year.

The calculator assumes a fixed rate and no fees, taxes or withdrawals. Real accounts and funds change rate over time, so treat the result as an illustration of the mechanism, not a forecast.

Common mistakes

  • Comparing a nominal yearly rate with an effective one (APY): the same 5% is a little higher once it compounds monthly.
  • Forgetting inflation: a balance that doubles in 14 years buys less than it appears to.
  • Assuming an investment return is guaranteed. Savings accounts pay a stated rate; stocks and funds do not.
  • Ignoring fees: a 1% yearly fee takes a large share of the growth over 30 years.

Questions

How much interest does this earn in 30 years?

With these inputs the interest is $9,936, on $1,000 paid in, for a final balance of $10,936.

How is compound interest different from simple interest?

Simple interest is paid only on the starting amount: here $2,400 over 30 years. Compound interest is also paid on interest already earned, so it comes to $9,936.

How often is the interest added?

This calculator compounds monthly. Many savings accounts compound daily or monthly and funds reinvest continuously; the difference at the same yearly rate is small compared with the effect of time.

Does the result include tax, fees or inflation?

No. It is the plain mathematical result at a fixed rate. Subtract fees and taxes that apply to you, and remember that prices rise too.

Is the rate guaranteed?

Only if it is a fixed-rate product such as a term deposit. Market investments vary from year to year, so use a range of rates to see the spread of outcomes.

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