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Grams to Calories Calculator 2026
Protein, carbs, fat and alcohol grams — converted to calories in one step.
A grams-to-calories calculator is a tool that converts the weight of each macronutrient in a food into energy using standard Atwater factors: protein 4 kcal per gram, carbohydrate 4 kcal per gram, fat 9 kcal per gram and alcohol 7 kcal per gram.
Start Calculating ↓Convert grams to calories
About the Grams to Calories Calculator
Enter the grams shown on a label or recipe and the tool breaks down how many calories come from each macro and the total. Label totals can differ slightly because manufacturers may use fibre adjustments and rounding, so expect small differences rather than exact matches.
Grams to Calories Calculator: Key Facts to Know
- ✓ Protein: 4 kcal per gram. Carbohydrate: 4 kcal per gram.
- ✓ Fat: 9 kcal per gram — more than twice as energy-dense as protein or carbs.
- ✓ Alcohol: 7 kcal per gram, with no essential nutrients alongside.
- ✓ Fibre is often counted at about 2 kcal per gram on some labels, which can lower a label total slightly.
- ✓ Water, vitamins and minerals add weight but no calories.
Results from the Grams to Calories Calculator are estimates for general educational use on Smoothie Nutrition Calculator. They are not medical or dietetic advice — for personal medical nutrition questions, including pregnancy, diabetes and clinical nutrition such as TPN, always work with your doctor or a registered dietitian.
Frequently Asked Questions
Multiply fat grams by 9. For example, 15g of fat = 15 × 9 = 135 kcal.
Grams to Calories Calculator Guides & Articles
All 4 of our guides for this calculator — every one built on the same data as the tool above.
Grams to Calories Calculator 2026
A grams-to-calories calculator is a tool that converts the weight of each macronutrient in a food into energy using standard Atwater factors: protein 4 kcal per gram, carbohydrate 4 kcal per gram, fat 9 kcal per gram and alcohol 7 kcal per gram.
Read guide →
⚖️Grams to Calories Calculator 2026 | Tips Mistakes
Most wrong results from the Grams to Calories Calculator come from input mistakes, not the maths. Here are the five that matter most — and the fix for each.
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⚖️Grams to Calories Calculator 2026 | Deep Dive
Beyond the basics: the reference values, assumptions and limits behind the Grams to Calories Calculator, and how dietitians sanity-check its results.
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⚖️Grams to Calories Calculator 2026 | Worked Examples
Numbers land differently in context. Three everyday scenarios run through the Grams to Calories Calculator, with the input that mattered most in each.
Read guide →
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Every calculator on Smoothie Nutrition Calculator works the same way — pick from the dropdowns and see live totals.