Most people burn between 1,200 and 1,900 calories running a half marathon, with body weight being the single biggest factor. A 132-pound runner burns roughly 1,240 calories over 13.1 miles, while a 198-pound runner burns closer to 1,860. The actual number shifts based on your pace, the terrain, and how efficiently your body moves.
Calorie Burn by Body Weight
Your body weight determines more of your calorie burn than any other variable. Heavier runners expend more energy to move the same distance because they’re physically carrying more mass with every stride. Here’s what the numbers look like at a moderate pace (roughly 9:40 per mile) across a full half marathon:
- 132 lbs (60 kg): ~1,240 calories
- 154 lbs (70 kg): ~1,450 calories
- 176 lbs (80 kg): ~1,650 calories
- 198 lbs (90 kg): ~1,860 calories
These estimates use MET values, a standard way of expressing how much energy an activity costs relative to sitting still. Running at about 6 mph carries a MET value of 8, meaning you’re burning roughly eight times the calories you’d burn at rest. The formula is straightforward: multiply the MET value by your weight in kilograms by the number of hours you’re running. A 70 kg runner finishing in two hours at a MET of 8 lands right around 1,120 calories from the formula alone, though real-world estimates tend to be slightly higher once you account for the full metabolic picture.
How Pace Changes the Equation
Running faster burns more calories per minute but fewer total minutes on the course. These two forces partially cancel each other out, which is why distance matters more than speed for total calorie burn. Still, pace makes a meaningful difference. A runner cruising at 5 mph (12-minute miles) works at about 6 METs, while someone pushing 8 mph (7:30 miles) works at 11.5 METs. Over two hours versus 100 minutes, the faster runner typically comes out ahead in total burn by 10 to 20 percent for the same body weight.
The reason comes down to biomechanics. At higher speeds, your muscles contract more forcefully, your heart pumps harder, and your body generates more heat it needs to dissipate. All of that costs energy. But the gap between a slow half marathon and a fast one is smaller than most people expect, because the slower runner is out there working for an extra 30 to 60 minutes.
Running Efficiency Varies More Than You Think
Two runners who weigh the same and run at the same pace can burn noticeably different amounts of calories. The reason is running economy: how much oxygen (and therefore energy) your body needs to cover each mile. Research in Sports Medicine found that running economy can vary by as much as 30 percent among trained runners with similar fitness levels. A runner with smooth, efficient form simply uses less fuel per stride.
This means a newer runner will generally burn more calories over 13.1 miles than an experienced one of the same weight and pace. Beginners tend to have less efficient stride mechanics, more upper-body movement, and greater reliance on muscles that aren’t yet conditioned for distance. Over thousands of miles of training, your body learns to waste less energy, which is great for performance but means slightly fewer calories burned per mile.
Hills, Heat, and Other Course Factors
A flat road race and a hilly trail half marathon are two very different metabolic events. For every 1 percent of uphill grade, a 150-pound runner burns about 10 extra calories per mile, roughly a 12 percent increase. On a course with significant elevation gain, your total burn could climb several hundred calories above what you’d see on flat ground.
Wind resistance, temperature, and altitude also play roles. Running in heat forces your body to divert blood flow to the skin for cooling while simultaneously maintaining blood flow to working muscles, which raises your heart rate and energy cost. Cold weather increases calorie burn slightly as your body works to maintain core temperature, though the effect is modest during vigorous exercise. Trail surfaces like dirt, gravel, or sand require more stabilization from small muscles in your feet and ankles, adding a few percent to the total.
The Afterburn Effect
Your calorie burn doesn’t stop when you cross the finish line. After intense or prolonged exercise, your body stays in a heightened metabolic state as it repairs muscle tissue, replenishes fuel stores, and clears metabolic byproducts. This phenomenon, known as excess post-exercise oxygen consumption, can last anywhere from 15 minutes to 48 hours depending on how hard you pushed.
The extra calories from afterburn are real but more modest than many people assume. A University of New Mexico study on trained males who ran at 70 percent of their maximum capacity for 160 minutes found an average afterburn of about 162 calories. For a typical half marathon effort, expect somewhere in the range of 100 to 200 additional calories burned in the hours after you finish. It’s a nice bonus, but it won’t double your total.
Why Your Watch Might Be Wrong
If you’re relying on a GPS watch or fitness tracker, take the calorie number with a grain of salt. A Stanford University study tested seven popular fitness trackers and found that even the most accurate device was off by an average of 27 percent for calorie estimates. The least accurate missed by 93 percent. Heart rate data from these devices is generally reliable, but the algorithms that convert heart rate into calories introduce significant error.
The watches tend to be more accurate for steady-state running than for interval work or variable paces, so a half marathon effort (which is relatively consistent) is one of the better scenarios. Still, if your watch says you burned 1,500 calories, the true number could realistically fall anywhere between 1,100 and 1,900. Weight-based formulas using MET values aren’t perfect either, but they give you a reasonable ballpark without the added noise of sensor error.
What Your Body Is Actually Burning
During a half marathon, your muscles draw from two primary fuel sources: stored carbohydrates (glycogen) and fat. At moderate intensity, the mix is roughly 50/50, but as you push harder or deplete your glycogen stores, the balance shifts. Your body stores enough glycogen in muscles and liver to fuel roughly 90 to 120 minutes of moderate-to-hard running, which is right at the edge of most half marathon finishing times.
This is why fueling during the race matters. When muscle glycogen drops below a critical threshold, your muscles can’t produce energy fast enough to maintain your pace. That’s the biological basis of “the wall,” though it’s more common in full marathons. In a half marathon, most runners who start with full glycogen stores and take in some carbohydrates during the race can avoid a dramatic energy crash. Taking in 30 to 60 grams of carbohydrates per hour through gels, chews, or sports drinks helps preserve glycogen and maintain performance in the later miles.
A Quick Way to Estimate Your Burn
For a rough but useful estimate, multiply your body weight in pounds by 0.63. That gives you an approximate calorie burn per mile at a moderate pace. Then multiply by 13.1. A 160-pound runner gets about 101 calories per mile, or roughly 1,320 calories for the full half marathon. This lands slightly below the MET-based estimates because it’s closer to a net calorie figure (subtracting what you’d burn at rest anyway), while most published tables report gross calories.
If you ran on a hilly course, add 10 to 15 percent. If it was hot, add another 5 to 10 percent. If you’re newer to running and your form still feels a bit rough, your actual burn is likely on the higher end of any estimate you calculate. For most people finishing a half marathon in 1:45 to 2:30, the total lands solidly between 1,200 and 1,800 calories, with body weight being the dominant variable.