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Performance tools
Science-based calculators to plan your race fuel, measure hydration, and optimise every training session.
Performance
View all performanceRunning Pace Calculator — Pace, Speed & Race Projections
Calculate your running pace per km and per mile, speed, and projected finish times for 5K, 10K, Half Marathon, and Marathon.
Sweat Rate Calculator — Hydration Deficit & Fluid Needs
Calculate your personal sweat rate per hour, hydration deficit, and post-exercise fluid replacement target based on pre and post-exercise body weight.
Heat Hydration Calculator — Running in Hot Weather Fluid Needs
Calculate your adjusted hourly fluid and sodium needs for running or racing in hot and humid conditions, with warning levels for dangerous heat loads.
Heat Acclimation Calculator — Induction, Decay & Race Readiness
Track how far through a heat acclimation block you are, how much you have lost since your last heat session, and what will be left on race day.
Natural Muscular Potential
Predict your maximum drug-free muscle size (FFMI) based on your wrist and ankle bone structure.
Cycling Power Zones (7-Zone)
Calculate your training zones (Recovery, Tempo, Sweet Spot, VO2 Max) based on your FTP.
Training Load Calculator — ATL, CTL & TSB Form Score
Calculate your Acute Training Load (ATL), Chronic Training Load (CTL), and Training Stress Balance (TSB) to identify your current form and optimal race window.
Race Altitude Adjustment Calculator — High Altitude Pace & Hydration
Calculate your adjusted race pace, extra hydration needs, and acclimatisation requirements for racing or training at altitude, based on Daniels' altitude formula.
Race Weight Estimator — Optimal Running Weight & Pace Gain
Calculate your optimal race weight based on lean mass and target body fat, and see the exact pace improvement per kilogram lost.
ACWR Calculator — Acute:Chronic Workload Ratio for Runners
Compare this week's training load against your previous three weeks to spot an unintended ramp. Reports the uncoupled ratio, which avoids the statistical artefact in the original formula.
Nutrition
View all nutritionCarb Loading Calculator — Race Nutrition by Body Weight
Calculate your exact carbohydrate loading targets before a 5K, 10K, Half Marathon, or Marathon based on body weight and ACSM guidelines.
Race Day Nutrition Planner — Gel Schedule & Carb Targets
Plan your complete race day nutrition: total carbs needed, exact gel timing schedule, and fluid intake targets based on race distance and pace.
Marathon Gel Calculator — How Many Gels Do You Need?
Calculate the exact number of energy gels for your marathon based on your target finish time and body weight, with a precise minute-by-minute gel schedule.
Triathlon Nutrition Calculator — Sprint to Ironman Fueling Plan
Get your complete triathlon nutrition plan for Sprint, Olympic, 70.3, or 140.6 distances — including gels per segment, fluid targets, and transition nutrition strategy.
Ultra Marathon Fueling Planner — 50K to 100 Mile Nutrition Strategy
Plan your complete ultra marathon nutrition: calorie targets, gel phase vs real food phase, aid station strategy, and drop bag checklist for 50K, 50 Mile, 100K, and 100 Mile races.
Caffeine Gel Timing Calculator — When to Take Caffeinated Gels
Calculate the optimal timing for caffeinated energy gels during your race based on finish time, body weight, caffeine tolerance, and race start time.
Pre-Race Meal Planner — What to Eat Before a Race (5K to Ultra)
Get your complete pre-race nutrition timeline — from 2 nights before to 45 minutes before the start — for any race distance, personalised by body weight.
Race Fuel Comparison — Gels vs Sports Drinks vs Bars
Compare energy gels, sports drinks, and energy bars for your specific race duration and intensity — with a personalised recommendation and strategy.
Post-Race Recovery Calculator — Protein, Carbs & Fluid After Racing
Get your personalised post-race recovery nutrition plan — protein and carb targets for the first 30 minutes, 4 hours, and 24 hours after any race distance.
Energy Availability Calculator — RED-S Risk Screening
Work out your energy availability in kcal per kg of fat-free mass and see whether you are fuelling enough to avoid Relative Energy Deficiency in Sport.
Gut Training Calculator — Build Carb Tolerance Before Race Day
Turn your current fuelling rate and your race target into a week-by-week progression, with the glucose and fructose split each step needs.
Health
View all healthElectrolyte Calculator for Athletes — Sodium, Potassium & Magnesium
Calculate your hourly and total electrolyte needs during exercise based on body weight, duration, intensity, and temperature.
Ferritin Calculator — Iron Status Thresholds for Athletes
Read your ferritin result against the thresholds used for endurance athletes, which sit higher than standard reference ranges, with checks for inflammation and anaemia.
Menstrual Cycle Calculator for Athletes — Phase & Race Day Planner
Work out which cycle phase you are in today and which one your race falls in, with an honest read on what the training evidence does and does not support.
Sports
View all sportsFasted Running Fuel Guide — Should You Eat Before a Run?
Find out whether to eat before your run, what to eat, and whether fasted training is appropriate — based on your run duration, intensity, and goal.
Marathon Wall Predictor — Will You Hit The Wall?
Assess your risk of hitting the marathon wall based on your training mileage, longest run, carb loading plan, and gel strategy — with a personalised fix.
Running Calorie Burn Calculator — Calories & Fuel Used Per Run
Calculate the exact calories burned, glycogen depleted, and fat used during any run — plus how many gels you need to replace the carbohydrate burned.
Sweat Test Calculator — Your Personal Sweat Rate in oz/hr
Calculate your exact sweat rate and fluid replacement needs using the professional weigh-in/weigh-out sweat test method, with results in oz/hr and sodium estimates.
Gel Season Budget Calculator — How Many Gels Do You Need Per Year?
Calculate the total number of energy gels you need for your entire race season — including training long runs and all planned races — with an estimated annual cost.