📈 Compound Interest

$1,000 at 9% for 15 Years

Investing $1,000 at 9% annual compound interest for 15 years grows to $3,642. That's $2,642 earned in interest on top of your original $1,000.

If you want to adjust the return assumption, extend the timeframe, or add regular contributions, use the compound interest calculator.

If you want the plain-English explanation behind the numbers, read our guide to compound interest.

Compound Interest Calculator
Australia 2026
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%
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Total value after 15 years
$3,642
Amount invested$1,000
Interest earned$2,642
Interest multiplier3.64×
Year-by-year growth
YearBalanceInterest
Yr 1$1,090+$90
Yr 2$1,188+$98
Yr 3$1,295+$107
Yr 4$1,412+$117
Yr 5$1,539+$127
Yr 6$1,677+$138
Yr 7$1,828+$151
Yr 8$1,993+$165
Yr 9$2,172+$179
Yr 10$2,367+$195
Yr 11$2,580+$213
Yr 12$2,813+$232
Yr 13$3,066+$253
Yr 14$3,342+$276
Yr 15$3,642+$301
Final balance after 15 years
$3,642
Invested
$1,000
Interest earned
$2,642
Multiplier
3.64×

How $1,000 grows at 9%

Compound interest earns returns on your returns — not just your original investment. At 9% per year, your money doubles every 8 years (the Rule of 72). Over 15 years, that compounds to a 3.64× multiplier.

In year 1, $1,000 earns $90 in interest. By year 15, the annual interest has grown to $301 — because each year's interest is calculated on a larger balance.

This is why longer holding periods matter so much. The later years do more of the heavy lifting, especially once the balance is large enough to generate bigger dollar returns each year.

$1,000 for 15 years at different rates
RateFinal balanceInterest earnedMultiplier
4%$1,801$8011.80×
5%$2,079$1,0792.08×
6%$2,397$1,3972.40×
7%$2,759$1,7592.76×
8%$3,172$2,1723.17×
9% ◀$3,642$2,6423.64×
10%$4,177$3,1774.18×

Year-by-year projection

YearBalanceInterest this yearTotal interestGrowth
Year 1$1,090+$90$901.09×
Year 2$1,188+$98$1881.19×
Year 3$1,295+$107$2951.30×
Year 4$1,412+$117$4121.41×
Year 5$1,539+$127$5391.54×
Year 6$1,677+$138$6771.68×
Year 7$1,828+$151$8281.83×
Year 8$1,993+$165$9931.99×
Year 9$2,172+$179$1,1722.17×
Year 10$2,367+$195$1,3672.37×
Year 11$2,580+$213$1,5802.58×
Year 12$2,813+$232$1,8132.81×
Year 13$3,066+$253$2,0663.07×
Year 14$3,342+$276$2,3423.34×
Year 15$3,642+$301$2,6423.64×

Growth chart

Balance growth over 15 years
$911$2k$3k$4kYr1Yr5Yr10Yr15
Principal
Interest earned

Frequently asked questions

Related compound interest scenarios

Use these nearby examples to compare what changes when you keep the same starting balance, extend the investing period, or test a more aggressive return assumption.

Compound interest guide and tools

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