Question 1

What does $500 grow to at 4% for 15 years?

Accepted Answer

$500 invested at 4% annual compound interest for 15 years grows to $900. Your original investment earns $400 in interest — a 80.1% total return and a 1.80× multiplier on your money.

Question 2

How long does it take to double money at 4%?

Accepted Answer

At 4% annual compound interest, your money doubles approximately every 18 years (the Rule of 72: 72 ÷ 4 = 18). Over 15 years, $500 has the potential to double 0.8 times.

Question 3

Is 4% a realistic return?

Accepted Answer

4% is a conservative assumption achievable through high-interest savings accounts or term deposits. It's a realistic baseline for low-risk investments, though actual rates vary with market conditions.

Question 4

What's the effect of adding regular contributions?

Accepted Answer

These figures show a one-time lump sum of $500 with no additional contributions. Adding regular contributions compounds the growth dramatically. For example, adding $200/month to $500 at 4% for 15 years would result in a significantly larger final balance. Use the interactive calculator above to model your own contribution amount.

Question 5

How does inflation affect this result?

Accepted Answer

This calculator shows nominal returns — the dollar figures before adjusting for inflation. Australia's historical inflation rate is around 2–3% per year. To estimate real purchasing power, subtract the inflation rate from your return: at 4% return and 2.5% inflation, your real return is approximately 1.5% p.a. In real terms, $900 in 15 years would buy meaningfully less than it does today.

Year	Balance	Interest
Yr 1	$520	+$20
Yr 2	$541	+$21
Yr 3	$562	+$22
Yr 4	$585	+$22
Yr 5	$608	+$23
Yr 6	$633	+$24
Yr 7	$658	+$25
Yr 8	$684	+$26
Yr 9	$712	+$27
Yr 10	$740	+$28
Yr 11	$770	+$30
Yr 12	$801	+$31
Yr 13	$833	+$32
Yr 14	$866	+$33
Yr 15	$900	+$35

Rate	Final balance	Interest earned	Multiplier
4% ◀	$900	$400	1.80×
5%	$1,039	$539	2.08×
6%	$1,198	$698	2.40×
7%	$1,380	$880	2.76×
8%	$1,586	$1,086	3.17×
9%	$1,821	$1,321	3.64×
10%	$2,089	$1,589	4.18×

Year	Balance	Interest this year	Total interest	Growth
Year 1	$520	+$20	$20	1.04×
Year 2	$541	+$21	$41	1.08×
Year 3	$562	+$22	$62	1.12×
Year 4	$585	+$22	$85	1.17×
Year 5	$608	+$23	$108	1.22×
Year 6	$633	+$24	$133	1.27×
Year 7	$658	+$25	$158	1.32×
Year 8	$684	+$26	$184	1.37×
Year 9	$712	+$27	$212	1.42×
Year 10	$740	+$28	$240	1.48×
Year 11	$770	+$30	$270	1.54×
Year 12	$801	+$31	$301	1.60×
Year 13	$833	+$32	$333	1.67×
Year 14	$866	+$33	$366	1.73×
Year 15	$900	+$35	$400	1.80×

Year	Balance	Interest
Yr 1	$520	+$20
Yr 2	$541	+$21
Yr 3	$562	+$22
Yr 4	$585	+$22
Yr 5	$608	+$23
Yr 6	$633	+$24
Yr 7	$658	+$25
Yr 8	$684	+$26
Yr 9	$712	+$27
Yr 10	$740	+$28
Yr 11	$770	+$30
Yr 12	$801	+$31
Yr 13	$833	+$32
Yr 14	$866	+$33
Yr 15	$900	+$35

$500 at 4% for 15 Years

How $500 grows at 4%

Year-by-year projection

Growth chart

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