# Hall effect sensor operational distance from magnet

I want to use a this hall effect sensor to detect the presence of magnet. I'm pretty sure I understand how to use the hall effect sensor, but I'm not sure how to calculate the distance the sensor can detect a magnet of a given Gauss. I'm not even sure that the Gauss rating is relevant to the question.

The Output On rating is listed as 35G and the Output Off is listed as 25G. If I use a magnet like this one (13,200 Gauss), can it be detected up to 6 inches (15 cm) away?

I found an online calculator to use but it appears to calculate the rating between two magnets and not a magnet and a sensor.

## 1 Answer

That depends a bit on how the magnet is oriented with respect to the sensor.

I would approach this question by first making the approximation that your magnet is a point dipole. Even though it is a cube, this approximation will be reasonable when you are an inch or so from the cube.

Therefore, you can use this equation for flux density at a given point. You will need to figure out the magnetic moment based on the specifications from the magnet manufacturer.

Then, determine the critical distance which results in a field of 35 Gauss.