You'll get slightly differing answers from different spoke calculators because there's no universal agreement on 2 key issues.
Some measure ERD (effective rim diameter)at the top of the nipple, while others including myself measure it at the point where the nipple meets the rim, so theres a difference of 3mm right there.
The other area of dissagreement is the ideal height of the spoke in the nipple on a finished wheel.
Structurally, the nipple should be considered a nut (the head) with an extension (the narrow section) for truing from outside the rim (towards the hub). Only the head provides any strength so spokes that do not fully engage 2mm into the head are too short, while any part of the spokes beyond the head is useless. The old school ideal length is for the spoke to end between the bottom of the slot and the top of the head.
Since no calculator tells you it's assumprions in advance, my suggestions is to decide which you plan to use, and build the front wheel first. That'll tell you if the calculations are off short or long, and by how much. From then on use the same correction factor with all future calculations (using the same calculator) and you'll be OK
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