Performance calculators
Deterministic fitness math for lifters and runners.
57 calculators for FFMI, DOTS, 1RM, VO2 max, Zone 2, race times, and recovery. Every formula sourced, every limit named.
Free · Private · No signup · 57 tools
What is AI Fit Hub?
Pick your goal
Optimize Body Composition
Optimize body composition with calorie targets that preserve strength while dropping body fat.
Open →Build Strength & Muscle
Build muscle by translating your calorie target into macro and protein plans for strength gains.
Open →Benchmark Your Strength
Benchmark your lifts against DOTS, strength standards, and 1RM projections.
Open →Plan Your Race
Plan race pacing, dial in training paces, and calibrate heart rate zones for distance running.
Open →Recover Better
Recover better by aligning sleep, hydration, and intensity to improve training quality.
Open →Understand Body Composition
Understand body composition with simple estimates that track direction over time.
Open →Worth reading.
Long-form articles
Evidence-backed, sourced, dated.
Evidence-Based Hypertrophy & Powerlifting Programming 2026
Evidence-based hypertrophy and powerlifting programming for 2026: 10-20 hard sets per muscle weekly, train each twice, load 30-85% near failure, periodize.
Zone 2 Training: What the Literature Says
Zone 2 training is work below LT1 (~65-75% HRmax), the easy base of Seiler 80/20. What the literature shows on dose-response, how to find it, and the limits.
Morton 2018 Protein: 1.6 g/kg, 2.2 Upper 95% CI
Morton 2018 placed the protein plateau at 1.6 g/kg with a 95% CI upper bound near 2.2 g/kg (49 studies, n=1,863). Cutting raises it to 2.3-3.1 g/kg lean.
Decide with evidence.
Popular comparisons
Head-to-head, sourced, no hype.
Calorie Counting vs Intuitive Eating Diet for Weight Loss
Calorie counting vs intuitive eating diet: counting gives faster fat loss, intuitive eating protects maintenance. See who each fits and how to combine both.
Strength vs Hypertrophy Training
Compare strength vs hypertrophy training to understand their distinct benefits, methodologies, and how to choose the right path for your training goals.
Zone 2 vs Zone 5 Training
Unpack the differences between Zone 2 and Zone 5 running training. Learn how balancing these heart rate zones builds endurance, speed, and prevents injury.
In under a minute.
Browse all 57 calculators.
FFMI, DOTS, 1RM, VO2 max, Zone 2, race times, recovery — every formula sourced.
FFMI
Calculate Fat-Free Mass Index to gauge muscularity and compare against natural benchmarks.
Open →1RM
Estimate one-rep max with Epley, Brzycki, and Lombardi formulas.
Open →Race Predictor
Race Time predictor: predict finish times across 5K, 10K, half marathon, and marathon from any known race result using Riegel's formula.
Open →