Running Calorie Calculator

Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Updated October 2026.

How many calories does running burn?

Running burns roughly 1 calorie per kilogram of body weight per kilometre, regardless of pace. That is about 60 to 110 calories per kilometre, or 100 to 180 per mile, depending on your weight. A 70kg runner burns around 350 calories over 5K, 700 over 10K, 1,480 over a half marathon and 2,950 over a marathon. For what to eat before and during the race itself, see my marathon fuelling guide.

Pace barely changes the total, because running faster burns more per minute but for fewer minutes; it changes how quickly you spend the same bill. Hills, headwinds and trail add 5 to 15 per cent. The calculator below does your exact numbers, in metric or imperial, and then does the thing most calculators skip: it tells you what those numbers mean for eating.

The honest number: gross vs net

Almost every running calculator flatters you. The figure your watch shows is gross: it includes the calories you would have burned sitting on the sofa for that hour anyway. The net figure, the true extra cost of the run, is the gross number minus roughly one calorie per kilogram per hour of resting burn. For a 70kg runner on a 60 minute 10K, that turns “700 calories burned” into about 630 net. Small difference on one run; across a training week it is the gap between the plan working and stalling. Our calculator shows both, because trusting the gross number is the most common maths error in running nutrition.

When does a run need fuelling, not just water?

Past about 75 minutes, your glycogen stores start running down, and performance follows. From 75 minutes to two and a half hours, 30 to 60 grams of carbohydrate per hour maintains pace; beyond that, trained stomachs handle 60 to 90 grams per hour. The best fuel is whatever you can actually eat at race effort, and your stomach can be trained to take more. Max, one of our customers, before his big one: “I had this just before the London marathon as a way of topping up the carbs before the race and am happy to confirm that it worked a treat! Felt fully energised throughout.” For context on the top end, one Phoenix Bar carries up to 557 calories and 60 to 66 grams of carbs in only 120g, roughly an hour of fuel at 60 grams an hour, broken into pocketable chunks. That density is why runners carry our high calorie protein bars on long Sunday efforts, and why they appear throughout our guide to the best energy bars for ultra running.

If you are heading past marathon distance, switch tools: the ultra running calorie calculator handles multi-hour burn and hourly fuelling for ultras properly. Walkers and hikers have their own maths in the walking calorie calculator and the calories burned hiking guide, and if you have ever run out of energy mid-race, our guide to hitting the wall explains what went wrong. Runners in heavy training blocks who struggle to hold body weight will find the opposite problem solved with high calorie bars for weight gain. If you are buying for a runner this Christmas, my guide to stocking fillers for runners lists small, useful presents, most of them under £15.

FAQ

How many calories does a 5K burn? About 1 calorie per kg of body weight per km, so roughly 300 calories at 60kg, 350 at 70kg and 425 at 85kg, whatever your pace.

Does running faster burn more calories? Per minute, yes; per mile, barely. The distance sets the bill, the pace sets how fast you pay it. Sprinting adds a modest afterburn, but for weight maths, distance is what counts.

How accurate are running calorie calculators? Within about 10 per cent for most runners on flat ground. Watches using heart rate drift further, typically overestimating. Terrain, wind and running economy are the main error sources, which is why we publish the formula rather than hiding it.

Should I eat back the calories I burn running? If you are maintaining weight, roughly yes, using the net figure. If you are training hard and losing weight you do not want to lose, eat back more than you burn. Appetite is often low after long runs, so dense foods help.

Rated 4.9 out of 5 from nearly 400 reviews. The formula here is the standard 1.0 kcal per kg per km model; we show our working because that is how it should be.