Every tool is a transparent estimate, not a measurement or diagnosis. Results depend on the inputs supplied and should be checked against real-world performance or trends. Formula changes are versioned in the release record; no calculator silently changes its method.
Energy and nutrition
TDEE starts with the Mifflin–St Jeor resting-energy equation and applies the selected activity multiplier. Deficit, surplus, macro, and meal-distribution tools use that estimate as an input. Protein ranges are expressed as practical starting ranges rather than a single medically required number. Water, glycogen, adherence, medication, illness, and adaptive changes can make observed weight change differ from an estimate.
Strength and rep max
One-rep-max tools use formula estimates from a submaximal load and reps. The output is uncertain, especially at high rep counts or when technique changes. Rep-max charts convert the estimate into a percentage table; they do not prescribe a mandatory load. Strength standards are labelled coaching benchmarks, not population percentiles.
RPE and RIR
RPE/RIR converts a reported effort and rep count into an estimated training-load range. Perceived effort is subjective, so the range is deliberately wider than a one-number prediction. Use a repeatable technique and stop if pain or unsafe fatigue changes the set.
Volume and progression
Volume totals count the exercises, sets, reps, and loads entered by the user. The progressive-overload planner creates a tracking framework; it cannot predict an individual’s adaptation. Reassess when performance, recovery, equipment, or schedule changes.
Programming tools
The generator and split quiz classify inputs into a practical starting structure. They do not create an indexable URL for every combination, and their output remains editable. Read the relevant plan or workout-splits guide for the reasoning behind a choice.
Limits and review
Seek individualized help for eating-disorder history, pregnancy, an injury, a health condition, medication-related weight changes, or a goal requiring clinical oversight. Each tool links here so users can inspect assumptions before relying on an output.
For a separate, repeatable field protocol and comparison limits for skinfold, DEXA, and BIA estimates, read the skinfold-caliper body-fat guide.