The last time I did these calcs, I used several so I could get a consensus:

Freespoke - https://www.kstoerz.com/freespoke/

UBI - https://bikeschool.com/resources/spoke-calculator/

QBP - https://spokecalculator.qbp.com/spok...ator/calculate

Pro Wheelbuilder - https://www.prowheelbuilder.com/spokelengthcalculator

Sapim - https://sapim.be/spoke-calculator

DT Swiss - https://spokes-calculator.dtswiss.com/en/calculator

Spoke Length Calculator - https://spokelengthcalculator.com/

Edd - https://leonard.io/edd/


I used these to calculate test spoke lengths for a 32h Shimano 5500 hubset, 3 cross, with a rim having ERD of 605.

Pretty sure I got data input for all of these right (some of them need data in different formats for offset), since with one exception all gave results within 0.5mm for both hubs. The "outlier" was Sapim, which gave a spoke length roughly 1mm higher than the rounded length suggested by the others.

Hope this helps, and best of luck.