Calculating magnetic field 4 feet away from 2 magnets

[Harborseal]

Hi! I'm new here. I took physics back when we calculated pterodactyl drag and I remember what an integral looks like but that's about it. I hope I chose the right prefix.

What I'd like to do is find the dimensions of N48 neodymium cylinder magnets that would produce a minimum field strength of 0.25 Gauss 4 feet (48") from the center of a line connecting 2 magnets 22 inches apart. The magnets would both have the N pole facing up and the poles are on the ends of the cylinders.

I also need to know how much moving both magnets 2" apart and 2" closer would affect the field strength at 4 feet.

Is there a free computer program, website or spreadsheet that could calculate this or give me a graph of lengths and diameters that would work?

I'm sure some of you know the answer off the top of your head so feel free to chime in. :)

Thanks.

 

[gleem]

Is there a free computer program, website or spreadsheet that could calculate this or give me a graph of lengths and diameters that would work?

Check this site out. https://www.kjmagnetics.com/gap.calculator.asp The calculation precision is only 0.1 Gauss so I do not know if this is satisfactory. Calculate the field for each magnet and add the results vectorially. I am suspicious that the fields will mostly cancel at the coordinate that you desire.because of the nature of the field line directions.