What is the formula to convert psi to bar?

One formula used to convert psi to bar is:

1 psi

= (32.174 lbm /1 lbf s2)x(0.45359237 kg /1 lbm)x(144 in2/1 ft2)x(1 ft /0.3048 m)

x(1 m s2 /105 kg)

= 0.06894747 bar

So 1 bar = 14.503795 psi

The Math behind it.

As psi is an imperial unit and bar is metric unit, we some constants

1 lb = 0.45359237 kg

1 ft = 0.3048 m

1 ft2 = 12 in x 12 in = 144 in2

And we have to rearrange some units

1 bar = 105 Pa = 105 Nm-2

And N = kg ms-2

so 105 Pa = 105 kgm-1s-2

Also note when applying newton's second law using imperial units we need to use a gravity constant 32.174 lbm /1 lbf s2

Metric

m x a = F

1 kg x 9.81 ms-2 = 9.81 N

Imperial units

m x a = F

1 lbm x 32.174 fts-2 ≠ 32.174 lbf need to use gravity constant gc

m x (a/gc) = F

1 lbm x (32.174 fts-2 / (32.174 lbm /1 lbf s2) = 1 lbf