How is a lumpsum investment calculated?

With the compound-interest formula: final value = amount × (1 + rate ÷ 12) raised to the power of the number of months. {{$50000}} at 10% for 5 years is {{$50000}} × (1.008333)⁶⁰ = {{$82265}}. Enter your amount, expected return and years and the page does the arithmetic.

Lumpsum or SIP — which is better?

If the money is already available and returns are expected to be positive, investing it at once earns more on average, because it compounds for longer. A SIP spreads the entry over months, which lowers the regret if the market falls just after you invest. Many people do both: lumpsum what they have, SIP what they earn.

How long does a lumpsum take to double?

About 72 ÷ rate years by the rule of 72: 9 years at 8%, 6 years at 12%, 7.2 years at 10%. With monthly compounding it is slightly quicker — 8.7 years at 8%. The CAGR page gives the exact doubling time for any rate.

What return should I assume?

Something you can defend: the long-run average of the asset class you are buying, less fees, rather than last year's figure. Run the page at two or three rates — a cautious one and a hopeful one — and plan on the cautious result.

Does monthly compounding make much difference?

A little. 8% compounded monthly works out to 8.30% a year (1.006667¹² − 1). Over ten years {{$10000}} reaches {{$22196}} with monthly compounding against {{$21589}} with yearly compounding.

Is the future value shown after tax?

No. It is before tax and fees; both reduce what you keep, so check how gains are taxed where you live.

Lumpsum Investment Calculator (One-Time Investment Growth)

What a one-time investment grows to at an assumed annual return, compounded monthly, with the interest earned.

Inputs

CurrencyAuto (USD)

Investment amount

$100$515,500

Expected return(%)

0 %30 %

Years(years)

1 years40 years

Include CalculateEveryday mark

Future value

$22,196

Future value

Principal$10,000(45%)
Interest$12,196(55%)

Principal: $10,000
Interest earned: $12,196

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What each Lumpsum Investment input means

Investment amount: The one-time amount you invest today.
Expected return: The yearly return you assume, before tax and inflation. The page compounds it monthly. Use a cautious figure: past returns are not guaranteed.
Years: How long the money stays invested.

Lumpsum Investment formula

A = P × (1 + r ÷ 12)^(12 × t) · interest earned = A − P · P = amount invested once, r = annual return, t = years

A = P\left(1 + \frac{r}{12}\right)^{12t}

A lumpsum investment is a single amount invested once and left to compound. Each month the balance earns one-twelfth of the annual rate on everything already there — the original amount and the growth so far — so the balance rises by a fixed factor each month and the curve steepens over time. That is the compound-interest formula with monthly compounding; a mutual fund does not credit interest monthly, so the rate here is an assumed average return, and the smooth curve is the average of a bumpy one. Because all the money is working from day one, a lumpsum beats the same total drip-fed as a SIP whenever returns are positive on average; the SIP's advantage is spreading the timing risk. The page shows the final value, the interest earned on top of the amount invested, and both as a split.

Lumpsum Investment worked example

$10,000 invested once at an assumed 8% a year, compounded monthly: the monthly rate is 8% ÷ 12 = 0.6667%, and there are 120 months, so the value is $10,000 × 1.006667¹²⁰ = $22,196 — $12,196 of growth, more than the amount invested. At 12% for 10 years the same $10,000 becomes $33,004; at 8% for 20 years, $49,268, because the second decade compounds on a base already doubled.

More Lumpsum Investment examples

$5,000 left for 20 years at 6% a year, compounded monthly: 5,000 × (1.005)²⁴⁰ comes to $16,551, more than three times the amount invested.

$25,000 at an assumed 10% for 15 years grows to $111,348 — about 4.45 times the start. At 8% the same money would reach about $82,700, which is why the assumed return matters so much.

Where the Lumpsum Investment calculator can give the wrong answer

The return is an assumption, not a forecast. Equity returns arrive in lumps with deep falls in between; the formula assumes the average arrives smoothly every month, which never happens.
Monthly compounding is a convention for this page. A bank deposit compounding quarterly, or a fund that simply grows, gives a slightly different figure for the same annual rate — the fixed deposit and CAGR pages handle those.
Fees and taxes are not deducted. Expense ratios come out of a fund's return before you see it, and capital-gains tax comes out at redemption; enter a net return, or reduce the final value yourself.
Inflation is ignored. {{$22196}} in ten years buys less than {{$22196}} today; the inflation-adjusted return page converts the rate to real terms.
Timing risk is real for lumpsums. Investing everything the week before a 30% fall changes the realised return for years, which is the case for splitting a large sum over several months.

Spotted a mistake? Tell us

Lumpsum Investment FAQ

: With the compound-interest formula: final value = amount × (1 + rate ÷ 12) raised to the power of the number of months. {{$50000}} at 10% for 5 years is {{$50000}} × (1.008333)⁶⁰ = {{$82265}}. Enter your amount, expected return and years and the page does the arithmetic.
: If the money is already available and returns are expected to be positive, investing it at once earns more on average, because it compounds for longer. A SIP spreads the entry over months, which lowers the regret if the market falls just after you invest. Many people do both: lumpsum what they have, SIP what they earn.
: About 72 ÷ rate years by the rule of 72: 9 years at 8%, 6 years at 12%, 7.2 years at 10%. With monthly compounding it is slightly quicker — 8.7 years at 8%. The CAGR page gives the exact doubling time for any rate.
: Something you can defend: the long-run average of the asset class you are buying, less fees, rather than last year's figure. Run the page at two or three rates — a cautious one and a hopeful one — and plan on the cautious result.
: A little. 8% compounded monthly works out to 8.30% a year (1.006667¹² − 1). Over ten years {{$10000}} reaches {{$22196}} with monthly compounding against {{$21589}} with yearly compounding.
: No. It is before tax and fees; both reduce what you keep, so check how gains are taxed where you live.