Why Different Ideal Weight Formulas Give You Different Numbers
Several different ideal weight formulas exist (Devine, Robinson, Miller, Hamwi among others), each developed independently using slightly different baseline assumptions and data — they produce broadly similar but not identical results for the same height, which is expected given they were derived separately rather than being variations of a single agreed formula.
Seeing several different "ideal weight" numbers from different formulas for the identical height isn't a sign any of them is wrong — it reflects that these are independently developed estimates, not measurements of a single objective fact.
Why multiple formulas exist in the first place
Each formula was developed by different researchers at different times, often for a specific clinical or dosing purpose, using their own baseline data and assumptions — there was never a single unified effort to define one universally agreed "ideal weight" formula, which is why several coexist today.
How much they typically differ
For a given height, most of these formulas produce results within a several-pound range of each other — a real but generally modest difference, especially compared to the much larger range of what's actually a healthy weight for different individual body compositions at that same height.
What to do with multiple different numbers
Rather than trying to determine which single formula is "correct," treating the range across a few formulas as a rough reference band — and weighing it alongside other health indicators — gives a more useful, honest picture than fixating on any one formula's specific output as a precise target.