• Your Number 1 Groundworks Contractor in Cambridge
  • Talk To Expert: 01223 665 555

French Drain Calculator

French Drain Calculator

This French drain calculator will help you find how much gravel you need for your French drain installation. This calculator also finds how many drain pipes and filter fabric you need for your French drain. This calculator also works as a French drain cost calculator to help you find how much your French drain would cost.

In this calculator, you will learn what a French drain is, how to build a French drain, whether it is a pipeless French drain or one with a French drain pipe. We’ll show you different French drain diagrams to help you visualize the different French drain systems. Keep on reading to start learning.

How to use our French drain calculator

Using our French drain calculator is very easy. Here are the steps that you can follow to use our tool properly:

  1. Select whether you want to build a French drain with a drain pipe or without a drain pipe. Choosing Yes will display the Drain pipe details section, and No will hide it.
  2. Select your filter fabric preference. The French drain diagram will change accordingly to help you visualize your selected French drain system.
  3. Enter your French drain depth, width, and length in our French drain calculator. The tool will then give you the volume of excavation you need for your French drain system.
  4. If you choose to make a French drain with pipe, the next step is to select the pipe schedule and choose the size of pipe you wish to use. You can enter a custom value for the pipe’s outside diameter in the Advanced mode if you have a special pipe size. With the outside diameter entered, our tool calculates the cylindrical volume of the pipe to subtract from the excavation volume to get the gravel volume.
  1. As you can see, there is already a value for the total drain pipe length. Our French drain calculator worked out this value based on the recommended slope for the selected drain pipe size. You can check and modify this slope value in the Advanced mode.

Right now, you should already have the volume and weight of gravel and the number of pipes you need. In construction, we always want to consider a contingency for the quantity of the materials we purchase. For that, we have included the wastage variable, which is the percentage of the volume of gravel you might end up wasting.

For the weight of gravel needed, we used a density value of 1,680 kg/m³ or 105 lb/ft³, which you can also edit in the Advanced mode if you are going to use a different kind of gravel or river rock.

Using our tool as a French drain cost calculator

How much your French drain costs depends on the size and length of your trench and the choice of materials you are going to use. With our tool, you can also find how much your French drain costs by entering either the price per weight or price per volume of gravel, the price per piece of pipe, and the price per unit area of filter fabric in the cost section of our French drain calculator.

Contact us for a free quote.