https://www.stewmac.com/FretCalculator.html, this will work, just enter bass instead of guitar
Thanks Darryl, I'll give that a shot.
Ubass (ukulele bass) scale length is 50 cm or 20 inches but you need the big fat silicone strings.
Before he had the hofner McCartney played a regular guitar with piano strings on it 66cm or 26inches. Not many do that by choice these days.
On a modern bass guitar, 30" (76 cm) or less is considered short scale, standard (also called long) scale is 34" (86 cm) for a 4-string and 35" (89 cm) for a B-E-A-D-G 5-string, and extra-long scale basses of 36" (91 cm) also exist.
These are the sorts of numbers you need to put into the stewmac or fretfind2d fret calculator.
The other issue is compensation. These fat strings need a lot to compensate for being bent plus having a high action to give them room to vibrate. The stewmac calculator gives some info on where to put an adjustable bridge.
I have made 30 and 34" scale fretted and fretless... 2 string... no truss rods...
Make what you want!