It is not usually specified in units of Tesla/Ampere/meter (or, more properly: Tesla-meter/Ampere).
At remanence for most NdFeB materials, the relative permeability is close to 1.05 multiplied by permeability of free space. The permeability of free space has two values, depending on if you are using SI units (Tesla, ampere/meter) or CGS (Gauss, Oersted)
In SI units, permeability of free space is 12.57*10E-7
In CGS units, permeability of free space is 1
I'm not sure what you mean by "how to calcuate this". Can you please describe your application?