Number of Turns: 100

Loop Diameter: 25 mm

Wire Diameter: 0.5 mm

Relative Permeability: 1000

I have used the AAC online calculator at https://www.allaboutcircuits.com/tools/coil-inductance-calculator/ and got the answer of 0.627 H using the formula Lcoil≈N^2 μ0 μr (D/2) [ln(8D/d)−2]

I have also used the rimstar online calculator at https://rimstar.org/science_electronics_projects/coil_design_inductance.htm and got the answer of 0.124 H using the formula

Could someone let me know which one of these is right?

Many thanks.