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Free Endurance Calculators & Race Planning Tools

Use 42 free endurance calculators to plan race pace, training zones, cycling power, swim workouts, fueling, and race day—no signup required.

Start with your goal

All Endurance Calculators

30-Minute Run Threshold Calculator

Estimate lactate threshold pace and zones from a 30-minute test (plus LTHR) or a recent 5K, 10K, or half-marathon race time. Pace per km or mile.

Running

Reference Weight Formula Comparison

Compare historical Hamwi and Devine height-based reference weights with clear limits—never presented as ideal racing or weight-loss targets.

NutritionGeneral

VDOT Calculator & Race Predictor

Enter a recent race to get your VDOT score, equivalent times from 1500m to marathon, and easy, threshold, and interval paces from the Daniels equations.

Running

VO2 Max Calculator & Fitness Estimator

Estimate VO2 max from a Cooper 12-minute test, 1.5-mile run, or maximum-to-resting heart-rate ratio.

RunningGeneral

PacePro - Race Pace Calculator

Calculate running pace per km and mile, cumulative race splits, and equivalent times for 5K, 10K, half marathon, or marathon goals.

RunningTriathlon

SWOLF Calculator

Calculate SWOLF from one length's time and arm-cycle count. See cycle rate, pool length per cycle, and 100 m or 100 yd pace for like-for-like swims.

Swimming

Cycling FTP Calculator

Calculate FTP from a 20-minute test (×0.95), a Zwift-style ramp test (×0.75 of best 1-min power), or a 2×8-min test (×0.90), plus W/kg and zones.

Cycling

Running Age Grade Calculator

Calculate a running age-grade percentage and age-adjusted time for ages 30–99 at 5K, 10K, half marathon, or marathon.

GeneralRunning

Cycling Power Zones (FTP)

Calculate seven contiguous cycling power zones in watts from FTP, including recovery, endurance, threshold, VO2 max, and sprint ranges.

CyclingTriathlon

CSS Swim Pace Calculator

Enter 400m and 200m test times to get your CSS pace per 100m and 100yd (6:00 and 2:50 = 1:35/100m), plus split times from 100m to 1500m.

SwimmingTriathlon

Swim Pace Converter

Convert any 100, 200, or 400 swim time to pace per 100m and 100yd (1:45/100m ≈ 1:36/100yd), then estimate 1500m, 1.9 km, and 3.8 km swim times.

SwimmingTriathlon

Advanced HR Zone Calculator

Calculate heart-rate training zones with Karvonen, maximum-HR, or running-specific lactate-threshold methods.

GeneralRunningCycling

Run-Walk Strategy Calculator

Calculate finish time and average pace for timed run-walk intervals.

RunningTriathlon

Walking Time & Pace Calculator

See how long it takes to walk a mile, 1 km, 5K, or a marathon at slow, moderate, or brisk speeds, or at your own walking pace per km or mile.

RunningGeneral

Track Split & Lane Calculator

Enter a distance and goal time to get 200m splits, full-lap targets, and lap counts for lanes 1–8. A lane-8 lap is about 453 m, not 400 m.

Running

Hill Grade & VAM Calculator

Enter climb distance and elevation rise to get the average hill gradient in percent (600 m over 10 km = 6%), plus VAM ascent rate and rise per km or mile.

RunningCycling

Race Cutoff Pace Planner

Calculate constant moving pace after stops and a safety buffer.

RunningGeneral

Cycling TSS Calculator

Estimate Training Stress Score from duration, NP, and FTP.

CyclingTriathlon

Bike Gear Speed Calculator

Calculate rollout and speed from gearing, wheel size, and cadence.

Cycling

Power-to-Weight Goal Calculator

Compare the power and weight paths to a target W/kg.

Cycling

Swim Interval & Send-Off Planner

Build repeat times, send-offs, distance, and total set time.

SwimmingTriathlon

Pool Set Distance Calculator

Add warm-up, main-set repeats, and cool-down to get total swim distance, lengths in a 25m, 50m, or 25yd pool, and estimated swim time at your pace.

Swimming

Open-Water Sighting Cost Calculator

Estimate open-water distance and added time from a course, pace, and chosen extra percentage.

SwimmingTriathlon

Carbohydrate Loading Planner

Calculate a transparent daily carbohydrate range by body mass.

NutritionRunningTriathlon

Hydration Bottle Planner

Turn an hourly fluid target into total fluid and bottle count.

NutritionCyclingTriathlonGeneral

Race-Morning Timeline Planner

Work backward from the start time to key race-morning actions.

GeneralRunningTriathlon

Triathlon Time Budget Calculator

Check whether planned legs and transitions fit a finish-time goal.

Triathlon

Triathlon Race Day Checklist

Build, save, reorder, and share a customizable race-day gear and preparation checklist.

TriathlonGeneral

Triathlon Predictor

Predict a Sprint, Olympic, 70.3, or full Ironman finish time from your swim pace, bike speed, run pace, and T1/T2, with the time for every leg.

Triathlon

Max Heart Rate Calculator

Compare max heart rate by age from 220 − age, Tanaka, Gulati and HUNT equations, and see the ±11 bpm error a field-measured max avoids.

GeneralRunningCycling

Marathon & Race Pace Planner

Build kilometer or mile race splits with even, positive, or negative pacing strategies.

RunningTriathlon

Endurance Fuel & Hydration Starting Points

Plan carbohydrate guidance by session duration, then calculate fluid and sodium totals from athlete-entered rates in metric or imperial units.

NutritionRunningCyclingTriathlon

Running Calories Burned Calculator

Estimate calories burned running from weight, pace, and distance or time with the ACSM equation. Gross and net kcal, per km and mile, with error.

RunningNutrition

Riegel Race Time Predictor

Estimate equivalent race times and paces from a recent performance with an adjustable Riegel exponent.

Running

Critical Power (CP) Calculator

Calculate your Critical Power and W' using the 3-minute all-out test, two-point, or three-point methods.

Cycling

W/kg Power Profile Analyzer

Calculate cycling watts per kilogram for 5-second, 1-minute, 5-minute, and FTP efforts.

Cycling

Race Taper Volume Calculator

Explore one illustrative exponential pre-race relative-volume curve.

GeneralTriathlon

Sweat Rate & Hydration Calculator

Estimate measured sweat rate from body-mass change, fluid intake, urine loss, and duration.

NutritionGeneral

Cycling CdA & Wattage Estimator

Roughly estimate aerodynamic drag and level-ground wattage using rider and bike mass.

CyclingTriathlon

BMR & TDEE Calculator for Athletes

Estimate BMR and activity-adjusted daily energy expenditure with published equations.

NutritionGeneral

BMI Calculator

Calculate your Body Mass Index with WHO classifications.

NutritionGeneral

Athlete Unit & Pace Converter

Convert min/km to min/mile pace, km/h to mph, km to miles, meters to yards (1.9 km ≈ 2,078 yd), and kg to lb using exact international factors.

General