Running Calculations Explained
Technical details about the calculations and formulas used in our Running Calculator. Understanding these methods can help you better interpret your results and improve your training.
Pace Calculations
Pace is calculated by dividing your total time by the distance covered. The result is expressed in time per unit distance (minutes per kilometer or mile).
Pace (min/km) = Total time (seconds) ÷ Distance (km) ÷ 60 Pace (min/mile) = Total time (seconds) ÷ Distance (miles) ÷ 60
The minutes and seconds components are separated for display purposes. For example, a pace of 5.5 minutes per kilometer would be displayed as 5:30 min/km.
Time Calculations
Time is calculated by multiplying your pace by the distance. This helps you estimate how long it will take to complete a run at a given pace.
Time (seconds) = Pace (min/km) × Distance (km) × 60 Time (seconds) = Pace (min/mile) × Distance (miles) × 60
This calculation is useful for race planning and setting realistic goals. Enter your target pace and race distance to estimate your finish time.
Distance Calculations
Distance is calculated by dividing your total time by your pace. This tells you how far you can run in a given time at a specific pace.
Distance (km) = Total time (seconds) ÷ Pace (min/km) ÷ 60 Distance (miles) = Total time (seconds) ÷ Pace (min/mile) ÷ 60
This calculation is helpful for planning training runs when you have a fixed amount of time available and want to know how far you can go.
Age Grading (WMA 2025)
Age grading is a method developed by World Masters Athletics (WMA) to compare performances across different ages and genders. Our calculator uses the latest 2025 factors.
The system works by comparing your time to an age-adjusted world record equivalent, accounting for the natural decline in performance with age.
Age-Graded Percentage = (Age Standard / Your Time) × 100 Age-Graded Time = Your Time × (Open-Class Factor / Age Factor)
Performance Level Categories
- World-Class (90%+) - Competitive at international championships
- National Class (80-89.9%) - Competitive at national championships
- Regional Class (70-79.9%) - Competitive at regional/state level
- Local Class (60-69.9%) - Competitive in local races
- Recreational (<60%) - Typical for recreational runners
Race Predictions
Race predictions estimate your potential times at standard race distances based on a completed performance. Our calculator uses multiple prediction models:
Riegel Formula (Peter Riegel)
T2 = T1 × (D2/D1)^1.06 Where: T1 = time for your known performance D1 = distance of known performance T2 = predicted time for new distance D2 = new distance 1.06 = fatigue factor
Cameron Method
T2 = T1 × (D2/D1)^1.07
These predictions assume similar conditions across distances. Most runners find they perform slightly better at their specialty distances compared to predictions.
World Record Comparison
This calculation compares your performance to the current world record at the closest standard distance.
Performance Percentage = (World Record Time / Your Time) × 100
Most recreational runners perform between 40-70% of world record level. Elite non-professional runners may reach 70-85%.
VO2max Estimation
VO2max is a measure of the maximum amount of oxygen a person can utilize during intense exercise. It's considered one of the best indicators of cardiorespiratory fitness.
Jack Daniels' VDOT Formula
Step 1: Oxygen Cost = -4.6 + 0.182258 × V + 0.000104 × V² Step 2: %VO2max = 0.8 + 0.1894393 × e^(-0.012778 × t) + 0.2989558 × e^(-0.1932605 × t) Step 3: VDOT = Oxygen Cost ÷ %VO2max Where: V = speed in meters per minute t = time in minutes
Typical VO2max Values
- Recreational runners: 35-45 ml/kg/min
- Competitive local runners: 45-55 ml/kg/min
- Elite male runners: 70-85 ml/kg/min
- Elite female runners: 60-75 ml/kg/min
Training Paces
Optimal training requires running at different intensities for different physiological adaptations. Our training pace calculator uses your estimated VO2max (based on Jack Daniels' VDOT system).
Training Zone Descriptions
- Easy/Long Run Pace - For recovery runs, warm-ups, cool-downs, and long runs.
- Marathon Pace - Your sustainable pace for marathon-distance races.
- Threshold Pace - Improves lactate threshold. Comfortably hard pace sustainable for about an hour.
- Interval Pace - For VO2max interval training (3-5 minute efforts).
- Repetition Pace - For short, fast repeats (200-400m).
A balanced training program typically includes 70-80% of your running at easy pace.
Frequently Asked Questions
What is age grading and why is it useful?
Age grading allows you to compare your performances across different ages, accounting for the natural decline in athletic abilities as we age. It's particularly valuable for masters athletes (40+) to track performance over time.
Why does my age grading differ from parkrun?
parkrun uses an older version of the WMA age grading tables. This calculator uses the latest 2025 WMA factors, which have been updated based on more recent world record performances and research into age-related performance decline.
How accurate are the race predictions?
Race predictions are most accurate when predicting similar distances (e.g., 5K to 10K) and when your training is balanced. They tend to be less accurate for very different distances.
How do these predictions compare to Garmin or Strava?
This calculator uses the Riegel formula, a transparent mathematical approach based on a single race result. Garmin and Strava layer heart rate data, training load, and machine learning on top of similar formulas to personalize predictions. Their predictions can be more accurate if you use them consistently, but they require device data and are less transparent about how they work.
Why do I get different VO2max estimates from different formulas?
Each formula uses different mathematical relationships between running performance and oxygen consumption. Daniels' formula is the most comprehensive as it accounts for race duration.
How should I use the training paces in my running program?
Use Easy/Long Run Pace for recovery days and long runs (60-120+ minutes). Use Threshold Pace for tempo runs. Use Interval Pace for VO2max intervals. Use Repetition Pace for speed work.
What pace is a 4 hour marathon?
A 4 hour marathon requires an average pace of 5:41 per kilometer (9:09 per mile). This is a common goal time for recreational marathoners and represents steady, moderate effort over the full 42.195 km (26.2 miles) distance. To achieve this time, you'll need to maintain consistent pacing and have trained for endurance at this pace.
How fast is a 20 minute 5K?
A 20 minute 5K represents a pace of 4:00 per kilometer (6:26 per mile). This is a strong time for recreational runners and indicates good aerobic fitness. Running a 20 minute 5K typically corresponds to a VO2max around 45-50 ml/kg/min and represents roughly 80-85% age grading for most age groups.
Is a 2 hour half marathon good?
A 2 hour half marathon (21.1 km / 13.1 miles) is a solid time for recreational runners, requiring a pace of 5:41 per kilometer (9:09 per mile). For most runners, this represents good fitness and consistent training. However, 'good' is relative to your age, gender, and training background. Age grading scores above 50% are considered above average, with 70%+ being very competitive.
What is a good age grading score?
Age grading scores above 60% indicate competitive performance, 70%+ is very competitive (Regional Class), 80%+ is highly competitive (National Class), and 90%+ represents world-class performance. Scores of 50-60% are considered good for recreational runners. The percentage reflects your performance relative to world record standards adjusted for your age and gender.
What is a sub-3 hour marathon pace?
A sub-3 hour marathon requires maintaining a pace faster than 4:16 per kilometer (6:52 per mile) for the full 42.195 km. This is a competitive time that typically requires extensive training, including high weekly mileage, tempo runs, and long runs. Most sub-3 hour marathoners have a VO2max above 55 ml/kg/min and solid race-specific preparation.
How can I improve my running pace?
Improve pace through varied training: include easy runs (70-80% of volume), tempo runs at lactate threshold, interval training for VO2max development, and strength training. Consistent weekly mileage, proper recovery, and progressive overload are essential. Use a running calculator to determine appropriate training paces for your current fitness level, and focus on gradual improvement over time.
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This site does not collect, store, or share any personal information. All calculations are performed locally in your browser. Your inputs are stored only in the URL, which you control and can share if you choose.