Carbohydrate Calculator
Calculate your optimal daily carbohydrate intake based on your TDEE, activity level, and dietary goals.
Enter your daily calorie target to see recommended grams of carbohydrates. Most adults thrive on 45 to 65% of calories from carbs, about 225 to 325 g on a 2,000 kcal diet.
Use the calculator below to estimate carbohydrate targets from calories and diet style.
Calculate Carbohydrate Intake
Methodology and sources
Formula or method
Estimates TDEE from the Mifflin-St Jeor BMR and activity factor, applies the carbohydrate percentage range you choose, then converts carbohydrate calories to grams at 4 kcal per gram.
Basis and assumptions
- Balanced diets use the 45 to 65 percent carbohydrate range named in the tool.
- Low-carb, high-carb, and ketogenic ranges are calculator presets, not medical prescriptions.
- Activity-based gram-per-kg examples follow the sports nutrition guidance cited in the content.
- Standard arithmetic converts carbohydrate calories to grams using 4 kcal per gram.
What this tool does not decide
- Dietary treatment for diabetes, pregnancy, kidney disease, sport performance, or eating disorders. Consult a GP, registered dietitian, or healthcare professional.
- Food quality, fibre adequacy, blood glucose response, or whether a low-carb plan is appropriate for you.
Sources
- Mifflin-St Jeor (1990), Am J Clin Nutr 51:241-247
- Dietary Guidelines carbohydrate range, as named in this tool
- International Society of Sports Nutrition carbohydrate guidance, as named in this tool
Last checked: 2026-06-05
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 to 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 to 3 g/kg | 150 to 225g |
| Light exercise (30 min/day) | 3 to 5 g/kg | 225 to 375g |
| Moderate exercise (1 hr/day) | 5 to 7 g/kg | 375 to 525g |
| Heavy training (1 to 3 hrs/day) | 6 to 10 g/kg | 450 to 750g |
| Extreme (4+ hrs/day) | 8 to 12 g/kg | 600 to 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 to 3 hours before)
Eat a meal with 1 to 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 to 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 to 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 to 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.
Worked Carbohydrate Target Example
If your total daily energy target is 2,400 kcal and you choose a balanced diet, the calculator applies the selected carbohydrate percentage range and then converts calories to grams.
| Step | Example calculation | Result |
|---|---|---|
| Lower range | 2,400 x 45 percent | 1,080 kcal from carbs |
| Upper range | 2,400 x 65 percent | 1,560 kcal from carbs |
| Convert to grams | Divide by 4 kcal per gram | 270 to 390 g per day |
The middle of the range is a starting point. Training volume, appetite, food preference, and blood glucose response can all justify moving higher or lower.
Choosing the Right Carb Range
Balanced Eating
The 45 to 65 percent setting works well for many mixed diets. It leaves room for protein, fats, fibre-rich grains, fruit, vegetables, and legumes.
Low-Carb Preference
A lower percentage can help some people manage appetite, but it may reduce training intensity if total carbohydrate becomes too low.
Endurance Training
Longer or harder sessions rely on muscle glycogen. Active people often feel and perform better at the higher end of the range.
Blood Glucose Context
People with diabetes, gestational diabetes, or reactive hypoglycaemia should use medical guidance rather than calculator presets.
Quality Checks Before You Change Carbs
- Keep fibre visible. Whole grains, beans, lentils, fruit, and vegetables provide more than energy.
- Match carbohydrate timing to training. Higher-carb meals often work best before and after demanding sessions.
- Review total calories. Changing carb grams without checking calories can unintentionally change weight-loss or weight-gain pace.
- If you use insulin or glucose-lowering medication, ask your clinician before changing carbohydrate targets.
Carb Target Review Checklist
Use the gram target alongside meal quality, not as a reason to ignore food choices.
- Check whether the target leaves room for enough protein and dietary fat.
- Plan high-fibre carbohydrate sources before adding lower-fibre snacks.
- Move more carbs around demanding training days if performance is the priority.
- Review symptoms and blood glucose guidance with a clinician when relevant.
Related Nutrition Tools
How to use this tool
Enter your body details and activity level
Choose the dietary goal range
Calculate daily carbohydrate grams and meal guidance
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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Frequently Asked Questions
How many carbs should I eat per day?
Are low-carb diets effective for weight loss?
What's the difference between simple and complex carbs?
Do I need carbs to build muscle?
How does activity level affect carb needs?
What is the glycaemic index and why does it matter?
How many carbs should I eat before a workout?
Are carbs bad for weight loss?
How much fibre should I eat per day?
What are net carbs?
Do I need to carb-load before a marathon?
Can I survive on zero carbs?
Results are for general informational purposes only and should be checked before use. They are not professional advice. See our Disclaimer and Terms of Service.