Calculate 30 percent of a number

Take 30% out of a quantity is quite useful, especially to know the discount and offers that have that particular rebate.

Our percentage calculator will allow you to find out 30 percent of the number you need instantly. Just type in the figure, hit the Calculate button and you'll automatically know how much your 30% is. If you need to find out any other percentage, we also have a percent calculator in which you will be able to set the exact amount and percentage.

How to calculate 30 percent of an amount

To calculate 30 percent of a number manually we only have to apply a simple rule of three like the one below:

Formula for calculating 30%

In this case, we are left with two unknowns whose value we do not yet know:

  • B: Number from which we want to find your 30%
  • Nos quedaría conocer cuánto vale 'Y' cuyo valor sería el 30 por ciento del número inicial.

We can clear the value we are interested in as follows:

Y = quantity x 30 / 100 = quantity x 0.3

To make it clearer, here is a practical example of how to apply what we have just learned.

Calculate 30 percent of 50

Calculate 30 percent

To obtain the 30% of the number 100, we will use the mathematical expression that we have mentioned above:

Y = = = quantity x 0.3 = 100 x 0.3 = 30

As you can see, it is very easy calculate 30 percent of any number multiplying by 0.3.

Calculate 30 percent in Excel

If you need calculating 30% using a spreadsheet program as Excel, the formula to be used is as follows:


Dónde hemos puesto 'celda' tienes que escribir las coordenadas de aquella celda en la que se encuentre el número del cual quieres calcular el porcentaje. De esta forma, podrás utilizar esta aplicación incluida en Microsoft Office para calculate percentages automatically and without wasting time.

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