How this calculator works
The figure in the panel above is not the FDA's 400 mg reprinted. It is built in three steps.
1. An age and status baseline. Adults start at 400 mg a day, the level the
FDA cites
as not generally associated with negative effects. Over-65s start at 300 mg, 13-17s at 100 mg, and under-13s at zero.
Tick Pregnant and the baseline drops to 200 mg, the ceiling in
ACOG's committee opinion;
Breastfeeding sets 300 mg.
2. Your body weight. The tool multiplies your weight by 6 mg/kg for adults,
4.5 mg/kg for over-65s and 2.5 mg/kg for teenagers, then uses that number whenever it comes out
below the baseline. A 55 kg adult is capped at 330 mg rather than 400. For teenagers the
weight-based figure always wins. For reference,
EFSA
puts habitual daily intake at 5.7 mg/kg and single doses at 3 mg/kg, so the adult factor used
here is marginally the more permissive of the two.
3. Your sensitivity. The five-point sensitivity setting applies a multiplier
running from 1.3x on Low down to 0.7x on Extreme. This is the one step with no
guideline behind it: it is a self-reported adjustment, and on Low it can return a number
above 400 mg. Read anything over 400 mg as a personal estimate, not as permission - the official
ceilings do not move with a slider.
The meter then scores your tracked drinks against that limit: green to 50%, amber
to 100%, red above it.