📈 Compound Interest

$100,000 at 10% for 30 Years

Investing $100,000 at 10% annual compound interest for 30 years grows to $1,744,940. That's $1,644,940 earned in interest on top of your original $100,000.

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 30 years
$1,744,940
Amount invested$100,000
Interest earned$1,644,940
Interest multiplier17.45×
Year-by-year growth
YearBalanceInterest
Yr 1$110,000+$10,000
Yr 2$121,000+$11,000
Yr 3$133,100+$12,100
Yr 4$146,410+$13,310
Yr 5$161,051+$14,641
Yr 6$177,156+$16,105
Yr 7$194,872+$17,716
Yr 8$214,359+$19,487
Yr 9$235,795+$21,436
Yr 10$259,374+$23,579
Yr 11$285,312+$25,937
Yr 12$313,843+$28,531
Yr 13$345,227+$31,384
Yr 14$379,750+$34,523
Yr 15$417,725+$37,975
Yr 16$459,497+$41,772
Yr 17$505,447+$45,950
Yr 18$555,992+$50,545
Yr 19$611,591+$55,599
Yr 20$672,750+$61,159
Yr 21$740,025+$67,275
Yr 22$814,027+$74,002
Yr 23$895,430+$81,403
Yr 24$984,973+$89,543
Yr 25$1,083,471+$98,497
Yr 26$1,191,818+$108,347
Yr 27$1,310,999+$119,182
Yr 28$1,442,099+$131,100
Yr 29$1,586,309+$144,210
Yr 30$1,744,940+$158,631
Final balance after 30 years
$1,744,940
Invested
$100,000
Interest earned
$1,644,940
Multiplier
17.45×

How $100,000 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 30 years, that compounds to a 17.45× multiplier.

In year 1, $100,000 earns $10,000 in interest. By year 30, the annual interest has grown to $158,631 — 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.

$100,000 for 30 years at different rates
RateFinal balanceInterest earnedMultiplier
4%$324,340$224,3403.24×
5%$432,194$332,1944.32×
6%$574,349$474,3495.74×
7%$761,226$661,2267.61×
8%$1,006,266$906,26610.06×
9%$1,326,768$1,226,76813.27×
10% ◀$1,744,940$1,644,94017.45×

Year-by-year projection

YearBalanceInterest this yearTotal interestGrowth
Year 1$110,000+$10,000$10,0001.10×
Year 2$121,000+$11,000$21,0001.21×
Year 3$133,100+$12,100$33,1001.33×
Year 4$146,410+$13,310$46,4101.46×
Year 5$161,051+$14,641$61,0511.61×
Year 6$177,156+$16,105$77,1561.77×
Year 7$194,872+$17,716$94,8721.95×
Year 8$214,359+$19,487$114,3592.14×
Year 9$235,795+$21,436$135,7952.36×
Year 10$259,374+$23,579$159,3742.59×
Year 11$285,312+$25,937$185,3122.85×
Year 12$313,843+$28,531$213,8433.14×
Year 13$345,227+$31,384$245,2273.45×
Year 14$379,750+$34,523$279,7503.80×
Year 15$417,725+$37,975$317,7254.18×
Year 16$459,497+$41,772$359,4974.59×
Year 17$505,447+$45,950$405,4475.05×
Year 18$555,992+$50,545$455,9925.56×
Year 19$611,591+$55,599$511,5916.12×
Year 20$672,750+$61,159$572,7506.73×
Year 21$740,025+$67,275$640,0257.40×
Year 22$814,027+$74,002$714,0278.14×
Year 23$895,430+$81,403$795,4308.95×
Year 24$984,973+$89,543$884,9739.85×
Year 25$1,083,471+$98,497$983,47110.83×
Year 26$1,191,818+$108,347$1,091,81811.92×
Year 27$1,310,999+$119,182$1,210,99913.11×
Year 28$1,442,099+$131,100$1,342,09914.42×
Year 29$1,586,309+$144,210$1,486,30915.86×
Year 30$1,744,940+$158,631$1,644,94017.45×

Growth chart

Balance growth over 30 years
$436k$872k$1.3M$1.7MYr1Yr5Yr10Yr15Yr20Yr25Yr30
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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