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.
Core references
- Mifflin et al.: resting energy expenditure equation.
- International Society of Sports Nutrition: protein and exercise position stand.
- Strength-normalization review and the limits of simple ratios.
Frequently asked questions
- How accurate are formula-based calorie calculators like TDEE?
- Calculators provide an evidence-based estimate using the Mifflin-St Jeor equation, typically within 5% to 10% of true metabolic expenditure. Real-world energy expenditure varies based on non-exercise activity, digestion, and metabolic adaptation, so use results as a starting point and adjust based on scale trends over 2 to 4 weeks.
- How is a one-rep max estimated from submaximal repetitions?
- Our calculators use validated linear and exponential equations (such as Epley and Brzycki) based on sets of 1 to 10 repetitions completed near muscular failure. Sets performed above 10 reps have higher variance due to muscular endurance factors.
- Are strength standards based on general population data or lifters?
- Strength standards reflect bodyweight-relative benchmarks derived from drug-tested recreational and competitive resistance-trained lifters. They represent realistic milestones for individuals who train consistently with barbells.