Endurance decision tools

Running Calculators for Better Training and Race Decisions

Turn pace, race times, VO2max, training zones, fueling, recovery, and gear data into practical next steps.

Calculate pace Predict a race Find training zones

25+: priority running tools
5K to marathon: race planning
No signup: fast static calculators

Race cockpit Half marathon

Goal pace 5:41 / km 2:00:00 finish

Training zone Threshold controlled hard

Fueling cue 45-60g carbs per hour

Use the result to choose the next decision: pace, zones, fueling, recovery, or gear timing.

Start here

Choose the decision you need to make

Pace, speed, finish time I need a pace Convert between distance, time, pace, speed, and common race goals. Race equivalency I have a race result Project a 5K, 10K, half marathon, marathon, or custom-distance finish time. Workout intensity I need training paces Turn a recent race into easy, marathon, threshold, interval, and repetition paces. Aerobic capacity I want fitness context Estimate VO2max from race performance, resting heart rate, or a Cooper test. Race nutrition I need a fueling plan Estimate carbs, gels, and fueling timing for longer races and training runs. Gear timing I track my shoes Estimate when a pair is approaching its useful mileage limit.

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Race Planning

Goal times, pacing strategy, splits, and realistic finish predictions.

Explore Race Planning

Race Time Predictor Expected finish time for any race distance. Know your 5K? Predict marathon, half or 10K in seconds. … Running Pace Calculator Free running pace calculator. Converts between pace (min/km, min/mile), speed (km/h, mph), and finish … Marathon Pace Calculator Set a 26.2 mile goal time and instantly see your required pace per mile and per km, with key checkpoint … Half Marathon Pace Calculator Plan your 13.1 mile race with a target finish time. Get per-mile and per-km paces plus every mile split. … Negative Split Calculator Plan your race splits with a negative or even split strategy. Calculate first and second half paces to … Track Split Calculator Calculate your 200m and 400m lap splits needed to hit your target race time on a standard 400m track. …

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Pace And Splits

Convert goals into stable paces, race splits, treadmill settings, and mid-race decisions.

Explore Pace And Splits

Running Pace Calculator Free running pace calculator. Converts between pace (min/km, min/mile), speed (km/h, mph), and finish … Running Pace Converter Convert running pace between min/km and min/mile instantly. Calculate your race finish time or target … Track Split Calculator Calculate your 200m and 400m lap splits needed to hit your target race time on a standard 400m track. … Negative Split Calculator Plan your race splits with a negative or even split strategy. Calculate first and second half paces to … Treadmill Pace Converter Convert treadmill speed (mph or km/h) to running pace (min/km or min/mile). Includes incline adjustment …

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Training Zones

Use recent performance and physiology signals to choose smarter workout intensity.

Explore Training Zones

Training Zone Calculator Calculate your personalized running training zones from any race performance. Get Easy, Marathon, … Threshold Pace Calculator Calculate your lactate threshold pace from recent race times. Find a practical tempo pace range for … Easy Run Pace Calculator Calculate your recovery and easy run pace from a recent race result. Find a practical low-intensity range … VO2max Calculator Estimate your VO2max from running performance, resting heart rate, or fitness tests. Free online aerobic … Heart Rate Drift Calculator Estimate cardiac drift during long runs. Calculate how much your heart rate rises at the same pace over …

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Marathon Prep

Connect marathon goal pace, long-run durability, fueling, and risk checks before race day.

Explore Marathon Prep

Marathon Pace Calculator Set a 26.2 mile goal time and instantly see your required pace per mile and per km, with key checkpoint … Race Time Predictor Expected finish time for any race distance. Know your 5K? Predict marathon, half or 10K in seconds. … Marathon Wall Calculator Predict when you'll hit the wall in a marathon based on your glycogen stores, pace, and body weight. Plan … Race Fuel Calculator Calculate exactly how many gels, chews, or carbs you need during a race based on your finish time, body … Negative Split Calculator Plan your race splits with a negative or even split strategy. Calculate first and second half paces to …

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Fueling And Hydration

Plan the intake needed to make long races and demanding workouts less fragile.

Explore Fueling And Hydration

Race Fuel Calculator Calculate exactly how many gels, chews, or carbs you need during a race based on your finish time, body … Race Day Nutrition Calculator Plan your complete race day nutrition including pre-race carb loading and in-race fueling. Personalized … Running Hydration Calculator Calculate your fluid needs for running based on sweat rate, temperature, humidity, and duration. Reduce … Marathon Wall Calculator Predict when you'll hit the wall in a marathon based on your glycogen stores, pace, and body weight. Plan …

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Recovery And Load

Use training stress, drift, easy pace, and shoe age to decide when to push or back off.

Explore Recovery And Load

Training Load Calculator Calculate your training load, acute:chronic workload ratio (ACWR), and load risk using TSS, distance, or … Recovery Time Calculator Estimate recovery time between runs, races, intervals, and strength sessions based on intensity, workout … Heart Rate Drift Calculator Estimate cardiac drift during long runs. Calculate how much your heart rate rises at the same pace over … Easy Run Pace Calculator Calculate your recovery and easy run pace from a recent race result. Find a practical low-intensity range … Running Shoe Mileage Tracker Estimate when to replace running shoes based on current mileage, weekly usage, and shoe type. Use mileage …

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Mechanics And Gear

Translate running form, treadmill settings, power, and shoe wear into practical choices.

Explore Mechanics And Gear

Running Cadence Calculator Estimate a practical running cadence range based on your height and pace. Use stride rate as a form clue, … Running Stride Length Calculator Calculate your running stride length from pace and cadence. Understand how stride length and cadence … Running Economy Calculator Calculate your running economy — oxygen cost per km — from your VO2max and current pace. Understand how … Running Power Calculator Estimate your running power output in watts from pace, body weight, and terrain grade. Based on Minetti's … Treadmill Pace Converter Convert treadmill speed (mph or km/h) to running pace (min/km or min/mile). Includes incline adjustment … Running Shoe Mileage Tracker Estimate when to replace running shoes based on current mileage, weekly usage, and shoe type. Use mileage …

Product standard

Built Around The Runner's Next Question

Interpret the result

A number is not enough. Priority calculators are being upgraded to explain what the output means in training or racing terms.

Compare realistic options

Race goals, pacing choices, and training zones should be compared against recent performance, not guessed in isolation.

Choose the next action

Each calculator should point to the next useful decision: training pace, race prediction, fueling, recovery, or gear timing.

Stay fast and focused

The core experience remains lightweight, static, and free. Deeper product features will be added only where they improve decisions.

Make Better Running Decisions

RunCalc is being rebuilt around one clear purpose: helping runners and endurance athletes make better decisions.

The calculators are only the starting point. A useful result should help you understand what it means, compare realistic options, choose the next workout or race goal, and avoid common training mistakes.

What RunCalc Focuses On Now

Race planning: goal times, race predictors, pacing, negative splits, track splits, and Boston qualifying context.
Training intensity: easy pace, threshold pace, VO2max, heart-rate drift, and training zones.
Marathon preparation: marathon pace, wall-risk thinking, fueling, hydration, and race-day execution.
Running mechanics: cadence, stride length, running economy, power, treadmill conversion, and shoe mileage.
Recovery and load: recovery timing, training load, and decisions about when to push or back off.

The Product Standard

Every priority running calculator should eventually answer four questions:

What is my result?
What does it mean for my current fitness or goal?
What should I do next?
Which related decision should I make after this?

Some older calculators remain available while the site is repositioned, but the product direction is running and endurance first.