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Work back from a target

Enter the amount you want to reach and see the monthly contribution it takes. Uses the starting amount, rate and period above.

Enter a target to get the monthly contribution and the time it takes.

Valor al vencimiento

106,639,017

Capital 70,000,000 · Ganancia +36,639,017

Año 10Activos 106,639,017Capital 70,000,000Ganancia +36,639,017
200M150M100M50M00años2años4años6años8años10años
Activos Capital
Capital total70,000,000
Ganancia total+36,639,017
Rentabilidad total+52.3%

Supone aportes a fin de mes y capitalización mensual; es una cifra nominal antes de impuestos. No incluye impuestos, comisiones ni inflación.

Years for the principal to double

The rule of 72 — divide 72 by the annual return for a quick estimate.

At 7% a year the principal doubles in 10.2 years.
Annual return
Rule of 72
Exact
3%
24.0
23.4años
4%
18.0
17.7años
5%
14.4
14.2años
6%
12.0
11.9años
7%
10.3
10.2años
8%
9.0
9.0años
10%
7.2
7.3años
12%
6.0
6.1años
15%
4.8
5.0años
20%
3.6
3.8años

The exact formula is ln2 ÷ ln(1+r). This assumes the principal sits alone with no contributions, and excludes tax and fees.

Frequently asked questions

What is the difference between monthly and annual compounding?

How often the interest is folded back into the principal. Annual compounding does it once a year, monthly does it every month, so the same nominal 7% grows slightly faster monthly (about 7.23% effective). This calculator assumes end-of-month contributions with monthly compounding.

How much do I need to save each month to hit a target?

Enter the figure under Work back from a target and the required monthly amount appears. At 7% over 10 years, reaching 100 million takes about 580,000 a month. Stretch the same target to 20 years and it drops to about 190,000 — time does far more work than the amount does.

What is the rule of 72?

Divide 72 by the annual return and you get roughly how many years it takes to double: 8% gives 72÷8 = 9 years, 6% gives 12. The exact formula is ln2÷ln(1+r), and between 6% and 10% the two differ by about a tenth of a year — close enough for mental arithmetic. The table above shows both.

Are taxes and inflation included?

No. These are pre-tax nominal figures. In practice tax on interest and dividends plus fees come off the top, and inflation erodes what the same amount can buy. With 3% inflation, a 7% nominal return is closer to 4% in real terms.

What annual return should I enter?

There is no single right answer, and past figures do not guarantee future returns. What is certain is that the result grows steeply as you raise the rate, so it is safer to run both a conservative and an optimistic figure and read the outcome as a range rather than a number.