📈 Compound Interest

$10,000 at 6% for 40 Years

Investing $10,000 at 6% annual compound interest for 40 years grows to $102,857. That's $92,857 earned in interest on top of your original $10,000.

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 40 years
$102,857
Amount invested$10,000
Interest earned$92,857
Interest multiplier10.29×
Year-by-year growth
YearBalanceInterest
Yr 1$10,600+$600
Yr 2$11,236+$636
Yr 3$11,910+$674
Yr 4$12,625+$715
Yr 5$13,382+$757
Yr 6$14,185+$803
Yr 7$15,036+$851
Yr 8$15,938+$902
Yr 9$16,895+$956
Yr 10$17,908+$1,014
Yr 11$18,983+$1,075
Yr 12$20,122+$1,139
Yr 13$21,329+$1,207
Yr 14$22,609+$1,280
Yr 15$23,966+$1,357
Yr 16$25,404+$1,438
Yr 17$26,928+$1,524
Yr 18$28,543+$1,616
Yr 19$30,256+$1,713
Yr 20$32,071+$1,815
Yr 21$33,996+$1,924
Yr 22$36,035+$2,040
Yr 23$38,197+$2,162
Yr 24$40,489+$2,292
Yr 25$42,919+$2,429
Yr 26$45,494+$2,575
Yr 27$48,223+$2,730
Yr 28$51,117+$2,893
Yr 29$54,184+$3,067
Yr 30$57,435+$3,251
Final balance after 40 years
$102,857
Invested
$10,000
Interest earned
$92,857
Multiplier
10.29×

How $10,000 grows at 6%

Compound interest earns returns on your returns — not just your original investment. At 6% per year, your money doubles every 12 years (the Rule of 72). Over 40 years, that compounds to a 10.29× multiplier.

In year 1, $10,000 earns $600 in interest. By year 40, the annual interest has grown to $5,822 — 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.

$10,000 for 40 years at different rates
RateFinal balanceInterest earnedMultiplier
4%$48,010$38,0104.80×
5%$70,400$60,4007.04×
6% ◀$102,857$92,85710.29×
7%$149,745$139,74514.97×
8%$217,245$207,24521.72×
9%$314,094$304,09431.41×
10%$452,593$442,59345.26×

Year-by-year projection

YearBalanceInterest this yearTotal interestGrowth
Year 1$10,600+$600$6001.06×
Year 2$11,236+$636$1,2361.12×
Year 3$11,910+$674$1,9101.19×
Year 4$12,625+$715$2,6251.26×
Year 5$13,382+$757$3,3821.34×
Year 6$14,185+$803$4,1851.42×
Year 7$15,036+$851$5,0361.50×
Year 8$15,938+$902$5,9381.59×
Year 9$16,895+$956$6,8951.69×
Year 10$17,908+$1,014$7,9081.79×
Year 11$18,983+$1,075$8,9831.90×
Year 12$20,122+$1,139$10,1222.01×
Year 13$21,329+$1,207$11,3292.13×
Year 14$22,609+$1,280$12,6092.26×
Year 15$23,966+$1,357$13,9662.40×
Year 16$25,404+$1,438$15,4042.54×
Year 17$26,928+$1,524$16,9282.69×
Year 18$28,543+$1,616$18,5432.85×
Year 19$30,256+$1,713$20,2563.03×
Year 20$32,071+$1,815$22,0713.21×
Year 21$33,996+$1,924$23,9963.40×
Year 22$36,035+$2,040$26,0353.60×
Year 23$38,197+$2,162$28,1973.82×
Year 24$40,489+$2,292$30,4894.05×
Year 25$42,919+$2,429$32,9194.29×
Year 26$45,494+$2,575$35,4944.55×
Year 27$48,223+$2,730$38,2234.82×
Year 28$51,117+$2,893$41,1175.11×
Year 29$54,184+$3,067$44,1845.42×
Year 30$57,435+$3,251$47,4355.74×
Year 31$60,881+$3,446$50,8816.09×
Year 32$64,534+$3,653$54,5346.45×
Year 33$68,406+$3,872$58,4066.84×
Year 34$72,510+$4,104$62,5107.25×
Year 35$76,861+$4,351$66,8617.69×
Year 36$81,473+$4,612$71,4738.15×
Year 37$86,361+$4,888$76,3618.64×
Year 38$91,543+$5,182$81,5439.15×
Year 39$97,035+$5,493$87,0359.70×
Year 40$102,857+$5,822$92,85710.29×

Growth chart

Balance growth over 40 years
$26k$51k$77k$103kYr2Yr10Yr20Yr30Yr40
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.

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