Carb Cycling Macro Calculator

How it is calculated

Protein is the same on every day and is fixed at 2 g × body weight (kg), which costs protein g × 4 kcal. That amount is subtracted from each day's calorie target to get the calories left for carbohydrate and fat. On the high day, carbs g = remaining × 0.60 ÷ 4 and fat g = remaining × 0.40 ÷ 9. On the low day, carbs g = remaining × 0.15 ÷ 4. The 60/40 and 15% splits are fixed in the tool, not inputs, and no low-day fat figure is shown. Results are rounded to whole grams. Weight must be between 2 and 650 kg, and if protein alone reaches either day's calorie target nothing is left and no result appears.

Common mistakes

• Expecting the protein target to change between days. It is a flat 2 g per kg on both high and low days, so only carbohydrate (and high-day fat) moves.
• Reading the low-day carb figure as the whole low-day plan. Only 15% of the remaining calories become carbohydrate there; the rest of the day's calories still have to come from fat, which this tool does not list.
• Entering the two calorie targets in the wrong boxes. The tool does not check that the high day is higher: swapping 2600 and 1900 still gives numbers, but the labels no longer match the plan.
• Entering pounds instead of kilograms. 165 lb typed as 165 kg gives a 330 g protein target and cuts the carbohydrate figures sharply.
• Setting a low-day calorie target close to the protein cost. At 650 kcal for a 75 kg person, low-day carbs fall to 2 g, and at 600 kcal or less the tool shows no result.