How many calories does a marathon burn? Enter your weight and pace — get your result plus a fueling plan.
| Weight | kcal burned | Finish time |
|---|---|---|
| 50 kg / 110 lbs | ~2,060 kcal | ~4:41 |
| 60 kg / 132 lbs | ~2,470 kcal | ~4:41 |
| 70 kg / 154 lbs | ~2,880 kcal | ~4:41 |
| 80 kg / 176 lbs | ~3,290 kcal | ~4:41 |
| 90 kg / 198 lbs | ~3,700 kcal | ~4:41 |
| 100 kg / 220 lbs | ~4,110 kcal | ~4:41 |
A marathon (42.2 km / 26.2 miles) burns approximately 2,500–4,200 kcal depending on body weight. The reliable rule: 1 kcal per kg per km. A 70 kg runner burns roughly 70 × 42.2 = 2,954 kcal — the equivalent of an entire day's food intake in a single event.
Your body stores only 1,800–2,000 kcal of glycogen (muscle + liver). A marathon burns 2,500–4,000+ kcal. At some point — usually around km 30–35 (mile 18–21) — glycogen runs out and the body shifts to fat oxidation, which is 30–40% slower. This is "hitting the wall." The fix: consume 60–90g of carbs per hour from gels or sports drinks starting at km 10.
A full marathon burns approximately twice the calories of a half marathon — 2,900 vs 1,450 kcal for a 70 kg runner. However, post-race EPOC (afterburn) is also much higher, potentially adding 200–400 extra kcal over the following 24 hours.
2–3 days before: Carb-load at 8–10g/kg/day. Race morning: 200–400 kcal carbs, 2–3 hours before start. During the race: 1 energy gel (100 kcal) every 30–45 minutes from km 10 onward = 6–9 gels total. After: 1–1.5g carbs/kg + 25–30g protein within 30 minutes of finishing.
Here are estimated calories burned running a full marathon (42.2 km) at moderate pace by body weight:
50 kg — approximately 2,050 kcal · 60 kg — approximately 2,500 kcal · 70 kg — approximately 2,950 kcal · 80 kg — approximately 3,350 kcal · 90 kg — approximately 3,800 kcal · 100 kg — approximately 4,200 kcal
These figures assume moderate effort (approximately 9–10 km/h). Elite runners completing a marathon in under 2:30 will burn slightly fewer calories per km due to superior running economy, while beginners taking 5–6 hours may burn slightly more due to a less efficient gait.
Marathon finish times span a wide range. Elite runners (sub-2:10): extremely efficient, burning approximately 2,400–2,600 kcal. Competitive club runners (2:30–3:00): approximately 2,700–3,000 kcal. Recreational runners (3:30–4:30): approximately 2,900–3,200 kcal for a 70 kg runner. First-timers (4:30–6:00+): often 3,000–3,500+ kcal due to less efficient running form over extended duration.
The longer you are on your feet, the more total calories you burn — even if your average pace is slower. This is why novice runners often burn comparable or greater calories to experienced runners over the same 42.2 km distance.
A standard 16-week marathon training programme builds weekly mileage from approximately 40 km to a peak of 70–90 km before tapering. For a 70 kg runner, total running mileage over the training cycle is approximately 700–900 km, burning an estimated 49,000–63,000 kcal from running alone. This is equivalent to burning approximately 6–8 kg of fat over the training period, assuming no change in food intake.
In practice, marathon training dramatically increases appetite and many runners find their weight stays relatively stable despite high mileage. However, body composition typically improves significantly — less fat, more functional muscle — even when total body weight changes little.
Many runners are surprised to find their weight increases by 1–3 kg in the days following a marathon. This is normal and temporary. The causes are: glycogen replenishment (each gram of glycogen binds approximately 3 grams of water, causing fluid retention), inflammation from muscle damage, and increased food intake during recovery. This water weight typically resolves within 5–7 days as the body returns to normal hydration balance.
After recovery, most runners who trained consistently will find they have lost 2–5 kg of body fat compared to their pre-training starting weight, with improved lean mass and cardiovascular fitness. Using a calorie calculator throughout training helps track energy balance and make informed fuelling decisions.