Calculate your half marathon finish time, predict race performance from training pace or recent race results, and get personalized training pace recommendations for optimal performance.
The half marathon (21.0975 km or 13.1 miles) is one of the most popular race distances, offering a perfect balance between the accessibility of shorter races and the challenge of marathon running. This calculator helps you predict your finish time and provides personalized training paces to optimize your preparation.
Our calculator uses the scientifically validated Riegel formula to predict race times based on your current fitness level. Whether you input your training pace or a recent race result, you'll receive accurate predictions along with detailed split times and training recommendations tailored to your goal pace.
Most half marathon training plans range from 10-14 weeks, depending on your current fitness level. Beginners should aim for 12-14 weeks, while experienced runners can prepare in 10-12 weeks.
Build your weekly mileage gradually, increasing by no more than 10% per week to reduce injury risk. Peak mileage typically reaches 30-40 miles per week for competitive runners.
Easy Runs: 70-80% of your weekly mileage should be at an easy, conversational pace. These build aerobic base and allow recovery.
Long Runs: Weekly long runs should gradually build to 10-13 miles, preparing your body for race distance while improving endurance.
Tempo Runs: Run at comfortably hard pace for 20-40 minutes to improve lactate threshold and race pace comfort.
Taper your training 2 weeks before race day, reducing mileage by 30-50% while maintaining intensity. This allows your body to recover and store energy for race day.
Focus on rest, hydration, and carbohydrate loading in the final 3 days. Avoid trying new foods or making drastic changes to your routine.
Start conservatively, running the first 3-5 miles slightly slower than goal pace. This prevents early fatigue and allows for a strong finish.
Aim for negative splits (second half faster than first) or even pacing throughout. The middle miles (6-10) are crucial for maintaining rhythm and mental focus.
| Level | Men | Women | Pace (min/km) |
|---|---|---|---|
| Elite | < 1:05:00 | < 1:12:00 | < 3:05 / < 3:25 |
| Advanced | 1:20:00 - 1:30:00 | 1:30:00 - 1:40:00 | 3:47 - 4:16 |
| Intermediate | 1:40:00 - 1:50:00 | 1:50:00 - 2:00:00 | 4:44 - 5:13 |
| Beginner | 2:00:00 - 2:15:00 | 2:10:00 - 2:30:00 | 5:41 - 6:20 |
| First Timer | > 2:15:00 | > 2:30:00 | > 6:20 |
In the 2-3 days before your race, increase carbohydrate intake to 60-70% of total calories to maximize glycogen stores. Eat familiar foods and avoid high-fiber or fatty foods that might cause digestive issues.
Eat a light, carbohydrate-rich breakfast 2-3 hours before the race. During the race, most runners don't need additional fuel for times under 1:45, but taking a gel or sports drink around mile 7-8 can help maintain energy for faster finishes.
Drink to thirst during the race, typically 4-8 oz every 15-20 minutes. In hot conditions, consider sports drinks with electrolytes. Practice your hydration strategy during training to find what works best for you.
Calculate running or walking pace
Calculate running pace and splits
Calculate marathon finish time
Calculate calories burned during exercise
Calculate one rep max strength
Calculate heart rate training zones