How Many Carbohydrates Do You Need During Exercise?
Calculate carbs needed per hour by duration and intensity. Reference table, gel and banana equivalents. Based on ACSM sports nutrition guidelines for runners, cyclists and endurance athletes.
See step-by-step calculation
When to use this calculator
- A marathon runner planning mid-race nutrition to avoid hitting the wall after mile 18
- A cyclist doing a 3-hour gran fondo who needs to calculate how many gels and chews to pack
- A soccer player trying to determine whether to take a sports drink during a 90-minute match
- A triathlete calculating carbohydrate needs across the bike and run legs of an Olympic-distance race
- A gym-goer asking whether they need intra-workout carbs during a 45-minute HIIT session
Carbohydrate Intake Targets by Duration and Intensity (ACSM Guidelines)
| Duration | Intensity | Target (g/hr) | Blend Required | Approx. Gels/hr |
|---|---|---|---|---|
| < 60 min | Low / Moderate / High | 0 (optional 20–30 at High) | No | 0–1 |
| 60–90 min | Low | 30 | No (glucose only) | ~1 |
| 60–90 min | Moderate | 45 | No (glucose only) | ~2 |
| 60–90 min | High | 60 | No (glucose only) | ~2.4 |
| 90–150 min | Low | 30 | No (glucose only) | ~1 |
| 90–150 min | Moderate | 45 | No (glucose only) | ~2 |
| 90–150 min | High | 60 | No (glucose only) | ~2.4 |
| > 150 min | Low | 50 | Recommended (2:1) | ~2 |
| > 150 min | Moderate | 70 | Required (2:1) | ~2.8 |
| > 150 min | High | 90 | Required (2:1) | ~3.6 |
Fuente: ACSM — Nutrition and Athletic Performance Position Stand; NIH/PMC6019055. Above 60 g/hr, a 2:1 glucose+fructose blend is required to avoid GI saturation (SGLT1 transporter limit ~60 g/hr glucose). Each gel ≈ 25 g carbs.
How it works
Reference Table: Carbs per Hour by Duration and Intensity
| Duration | Low intensity | Moderate intensity | High intensity |
|---|---|---|---|
| < 60 min | 0 g/hr | 0 g/hr | 0 g/hr (optional 20–30 g) |
| 60–90 min | 30 g/hr (1 gel) | 45 g/hr (2 gels) | 60 g/hr (2.4 gels) |
| 90–150 min | 30 g/hr | 45 g/hr | 60 g/hr |
| > 150 min | 50 g/hr (2 gels) | 70 g/hr (2.8 gels) | 90 g/hr (3.6 gels)* |
*Above 60 g/hr a 2:1 glucose+fructose blend is required to avoid GI saturation.
Common Sports Food Equivalents (~25–30 g carbs)
| Food | Serving | Carbs (g) | Best for |
|---|---|---|---|
| Energy gel (standard) | 1 packet | ~25 | Running, triathlon |
| Banana (medium) | 1 unit (~118g) | ~27 | Cycling, transition |
| Sports drink (Gatorade) | 500 mL | ~30 | Hydration + carbs |
| Medjool date | 2 units | ~36 | Ultra-endurance |
| Sports chews (Clif Bloks) | 3 units | ~24 | Long runs |
How It Is Calculated
Recommendations are based on ACSM guidelines:
Total session carbs are calculated on effective fueling time (subtracting the first 30 min where glycogen covers the effort):
Total (g) = g/hr × (duration_min − 30) / 60
Gels = Total ÷ 25
Bananas = Total ÷ 27> Physiological note: The gut absorbs a maximum of 60 g/hr of pure glucose (SGLT1 transporter). To exceed that ceiling without GI distress, fructose (GLUT5 transporter) must be added — hence the 2:1 blend for long efforts.
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Typical Use Cases With Numbers
Case 1 — Marathon Runner (75 kg, 4-hour race, High Intensity)
Case 2 — Recreational Cyclist (68 kg, 90 min ride, Moderate)
Case 3 — HIIT Gym Session (80 kg, 45 min, High)
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Common Mistakes
1. Fueling only when hungry — Hunger is a late signal of glycogen depletion. By the time you feel it, performance has already dropped. Start fueling at 30–45 min into any session over 75 minutes.
2. Using only glucose-based gels for long efforts — The gut maxes out at ~60 g/hr of glucose alone. Adding fructose unlocks absorption up to 90 g/hr. For efforts > 2.5 hours, choose a 2:1 maltodextrin/fructose product.
3. Not accounting for carbs already in sports drinks — Many athletes double-dose without realizing their drink already contains 30–40 g/hr. Total carbohydrate intake from all sources must stay within the 60–90 g/hr window.
4. Not practicing race nutrition in training — The gut is trainable. Athletes who never practice intra-workout fueling often experience nausea or cramping on race day. Train your gut during long training sessions.
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Related Calculators
75 kg runner, 2-hour run at high intensity
Frequently asked questions
How many grams of carbohydrates do I need per hour of exercise?
Do I need carbohydrates during a workout under 60 minutes?
What is the maximum carbohydrate absorption rate during exercise?
Is there a difference between carbohydrate needs for running vs. cycling?
What happens if I don't fuel during a long run or ride?
Are bananas a good source of carbohydrates during exercise?
How often should I take carbohydrates during exercise?
Can I use regular food instead of gels during exercise?
Should I adjust carb intake based on body weight?
Sources & references
Methodology & trust
Calculadora de deportes revisada por el equipo editorial de Hacé Cuentas, contrastada con NIH National Library of Medicine — Carbohydrate Intake and Exercise Performance, según nuestra política editorial y metodología.
Última revisión: June 20, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.
Calculations run 100% in your browser. We do not store or transmit your data.
Indicative results. For critical decisions, consult a professional.
Rodríguez, M. (2026). How Many Carbohydrates Do You Need During Exercise?. Hacé Cuentas. https://hacecuentas.com/carbohydrates-during-exercise
Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.