Skin Hydration Calculator

Skin Barrier Score is built from a fixed starting point of 5, plus a constant +2 for adequate hydration, plus adjustments that only check Climate and Skin Type (lines 38-42). Body Weight, Activity Level, Daily Caffeine Servings, and Daily Alcohol Servings all feed into Daily Water Intake, a separate output, but none of them are referenced anywhere in the Skin Barrier Score formula, so changing any of them leaves the score exactly where it was.

That term was originally written to compare Daily Water Intake against Base Water and add 2 points if intake met or exceeded the baseline, or subtract 1 if it did not. But because the Activity Level and Climate multipliers are never below 1.0 and the caffeine/alcohol diuretic offset is never negative, Daily Water Intake can mathematically never fall short of Base Water -- so the shortfall case was unreachable for every possible combination of inputs, and the term has been simplified to the constant +2 it always evaluated to.

Body Weight, by a wide margin. Body Weight sets the Base Water figure that the Activity Level and Climate multipliers then scale (lines 11, 14, 17), so a 10% change in Body Weight moves Daily Water Intake by roughly ten times as much as an equivalent 10% change in Daily Caffeine Servings, which only adds a flat 4 ounces per cup on top (line 20).

Daily Water Intake responds to Body Weight, Activity Level, Climate, and diuretic intake, while Skin Barrier Score only responds to Climate and Skin Type, plus a fixed baseline that assumes hydration is already adequate (lines 38-42). A very heavy caffeine or alcohol day can push Daily Water Intake much higher without moving Skin Barrier Score at all, since the score was never built to react to those two inputs.