Carb Calculator

Carbohydrate is the most flexible macro. Set protein first, fat to a floor, and carbohydrate takes the remainder — but it helps to know the range that supports your training.

Beginner Free, no sign-up Updated August 2026

What carbohydrate actually does for lifting

Less than people assume for a typical session, and more than the low-carb argument allows.

A hard set of ten reps takes about thirty seconds. A typical session contains fifteen to twenty-five working sets — so ten to fifteen minutes of actual work spread over an hour. Glycogen use is meaningful but not dramatic, and a well-fed lifter starts with plenty in reserve.

Which is why low-carbohydrate diets are workable for general lifting and get progressively worse as sessions become longer, more voluminous, or closer together. High-rep work suffers most — sets of twelve to twenty on squats are far more glycogen-dependent than sets of three.

The strongest case for carbohydrate

It is not that carbohydrate builds muscle directly. It is that it lets you train harder, and training harder is what causes the growth.

Practical notes:

  • In a deficit, carbohydrate is what gets cut once protein and a fat floor are set. Expect some drop in high-rep performance — that is normal.
  • Weight drops immediately on low carb, and it is not fat. Each gram of glycogen holds around three grams of water.
  • Feeling flat on low carbohydrate is real: less muscle glycogen means less fullness and less capacity for high-rep work.
  • If it suits you, it works. Adherence beats theoretical optimisation.

Common questions

How many carbs should I eat per day?

3–5 g per kg of body weight for general training; more with high volume or endurance work.

Do I need carbs to build muscle?

Not strictly. They help you train harder, which is the actual mechanism.

Are carbs bad for fat loss?

No. Controlled trials matching calories and protein find no advantage to low-carb diets for fat loss.

Should I eat carbs at night?

It makes no difference to fat gain, and some people sleep better for it.

Track the numbers, not just calculate them

MyFitsy stores your weight, measurements and every session, so the figures above become a trend instead of a one-off.

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