Carbohydrate Calculator
Calculate your optimal daily carbohydrate intake based on your TDEE, activity level, and dietary goals.
Calculate Carbohydrate Intake
Carbs Aren't the Problem — The Wrong Carbs Are
Carbohydrates have become the most misunderstood macronutrient. Keto enthusiasts demonise them. Marathon runners worship them. The truth, as usual, is in the middle.
Carbs are your body's preferred energy source. Your brain alone uses 120g of glucose per day — about 60% of all the carbs a sedentary person needs. During high-intensity exercise, carbs are the only fuel your muscles can burn fast enough to sustain the effort. Try sprinting on an empty glycogen tank and you'll understand why.
The real question isn't "should I eat carbs?" but "which carbs, and how many for my goals?" A sedentary office worker and a marathon runner have wildly different needs. This calculator gives you a personalised target based on your actual energy expenditure and goals.
Simple vs Complex Carbs
| Type | Examples | Digestion Speed | Best For |
|---|---|---|---|
| Simple (high GI) | White bread, sugar, fruit juice, sweets | Fast — blood sugar spikes quickly | During/immediately after exercise |
| Complex (low GI) | Oats, brown rice, sweet potato, lentils, vegetables | Slow — sustained energy release | Most meals throughout the day |
| Fibre | Vegetables, whole grains, beans, nuts | Not fully digested — feeds gut bacteria | Every meal (aim for 25–35g/day) |
What this means for you: Get 80% of your carbs from complex sources. The fibre slows digestion, keeps you fuller for longer, feeds beneficial gut bacteria, and prevents the blood sugar crashes that lead to afternoon energy slumps. Save simple carbs for during or right after exercise, when fast energy delivery is an advantage.
Carb Needs by Activity Level
| Activity Level | Carbs (g/kg/day) | Example (75 kg person) |
|---|---|---|
| Sedentary / low-carb diet | 2–3 g/kg | 150–225g |
| Light exercise (30 min/day) | 3–5 g/kg | 225–375g |
| Moderate exercise (1 hr/day) | 5–7 g/kg | 375–525g |
| Heavy training (1–3 hrs/day) | 6–10 g/kg | 450–750g |
| Extreme (4+ hrs/day) | 8–12 g/kg | 600–900g |
Source: International Society of Sports Nutrition. These are guidelines, not rigid targets. If you're trying to lose weight, the lower end of your range creates a calorie deficit. If you're trying to fuel performance, aim for the higher end. Use our TDEE Calculator to find your total calorie target first.
Carb Timing for Exercise
Pre-Workout (2–3 hours before)
Eat a meal with 1–2g carbs per kg of body weight. Choose complex carbs for sustained energy: oatmeal, rice, or whole grain toast. If eating closer to training (30–60 min), keep it smaller and simpler: a banana or a handful of dried fruit.
During Exercise (60+ min sessions)
For sessions over 60 minutes, consume 30–60g carbs per hour. Sports drinks, gels, or dried fruit work well. For ultra-endurance events (3+ hours), trained athletes can absorb up to 90g/hour using mixed glucose + fructose sources.
Post-Workout (within 2 hours)
Replenish glycogen with 1–1.5g carbs per kg. This is the one time simple carbs are ideal — the fast absorption accelerates glycogen resynthesis. Combine with protein (0.3g/kg) for enhanced recovery.
Rest Days
Reduce carb intake to the lower end of your range. Your muscles aren't depleting glycogen, so they need less replenishment. Focus on complex carbs with fibre and reduce simple carbs to keep blood sugar stable.
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How to use this tool
Select your preferred unit system
Enter your age, gender, height, and weight
Choose your activity level and dietary goal
Common uses
- Setting daily carb targets by dietary goal
- Planning low-carb or ketogenic diets
- Fuelling endurance training and recovery
- Managing blood sugar through diet
- Balancing macros for body composition
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