📈 Compound Interest

$500 at 10% for 15 Years

Investing $500 at 10% annual compound interest for 15 years grows to $2,089. That's $1,589 earned in interest on top of your original $500.

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
$2,089
Amount invested$500
Interest earned$1,589
Interest multiplier4.18×
Year-by-year growth
YearBalanceInterest
Yr 1$550+$50
Yr 2$605+$55
Yr 3$666+$61
Yr 4$732+$67
Yr 5$805+$73
Yr 6$886+$81
Yr 7$974+$89
Yr 8$1,072+$97
Yr 9$1,179+$107
Yr 10$1,297+$118
Yr 11$1,427+$130
Yr 12$1,569+$143
Yr 13$1,726+$157
Yr 14$1,899+$173
Yr 15$2,089+$190
Final balance after 15 years
$2,089
Invested
$500
Interest earned
$1,589
Multiplier
4.18×

How $500 grows at 10%

Compound interest earns returns on your returns — not just your original investment. At 10% per year, your money doubles every 7.2 years (the Rule of 72). Over 15 years, that compounds to a 4.18× multiplier.

In year 1, $500 earns $50 in interest. By year 15, the annual interest has grown to $190 — 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.

$500 for 15 years at different rates
RateFinal balanceInterest earnedMultiplier
4%$900$4001.80×
5%$1,039$5392.08×
6%$1,198$6982.40×
7%$1,380$8802.76×
8%$1,586$1,0863.17×
9%$1,821$1,3213.64×
10% ◀$2,089$1,5894.18×

Year-by-year projection

YearBalanceInterest this yearTotal interestGrowth
Year 1$550+$50$501.10×
Year 2$605+$55$1051.21×
Year 3$666+$61$1661.33×
Year 4$732+$67$2321.46×
Year 5$805+$73$3051.61×
Year 6$886+$81$3861.77×
Year 7$974+$89$4741.95×
Year 8$1,072+$97$5722.14×
Year 9$1,179+$107$6792.36×
Year 10$1,297+$118$7972.59×
Year 11$1,427+$130$9272.85×
Year 12$1,569+$143$1,0693.14×
Year 13$1,726+$157$1,2263.45×
Year 14$1,899+$173$1,3993.80×
Year 15$2,089+$190$1,5894.18×

Growth chart

Balance growth over 15 years
$522$1k$2k$2kYr1Yr5Yr10Yr15
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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