Macro Cycling Calculator

Why Cycle Macros Instead of Eating the Same Every Day

Most calorie targets assume you eat the same thing every day, but your actual energy demands don't work that way — a heavy lift session or a long run burns meaningfully more glycogen than a day spent at a desk. Macro cycling (often called carb cycling, since protein and the overall weekly average stay put) shifts carbohydrate and calorie intake to match that pattern: more carbs and calories on the days you train hard, fewer on the days you rest, while your weekly average still lands on the same calorie target you'd use for a flat daily plan. The appeal is practical — better fuel on hard days, easier adherence on easy ones — without changing your overall trajectory toward the goal you set.

How to Use This Calculator

Enter your sex, age, weight, and height, then pick the activity level that best matches a typical week and the goal you're working toward. Those inputs are exactly what a standard maintenance-calorie estimate needs. The one addition here is training days per week — how many days count as high-carb, higher-intensity days. Whatever's left over in the seven-day week becomes low-carb rest days. Use the number that reflects your real training split, not an aspirational one; the split only helps if the two day types line up with when your body actually needs the extra fuel.

How We Split Calories Between Day Types

We start with a standard maintenance estimate: Basal Metabolic Rate from the Mifflin-St Jeor equation, multiplied by an activity factor for Total Daily Energy Expenditure (TDEE), then adjusted ±500 calories for a weight-loss or weight-gain goal. That gives your weekly average calorie target. Protein is set at 1.8 g per kg of bodyweight and held identical on every day — it's the one macro that isn't cycled. High-carb days are calculated at 15% above your average target, with 60% of that day's calories coming from carbs. Low-carb days aren't a fixed percentage below average; instead we solve for whatever calorie level makes the full week balance out exactly, given how many high- and low-carb days you chose, then allocate 30% of that day's calories to carbs. Fat fills whatever's left after protein and carbs on both day types.

A Worked Example

Take a 30-year-old man, 80 kg, 178 cm, moderately active, aiming to maintain weight, with 4 training days and 3 rest days a week. BMR works out to about 1,768 calories, and TDEE (×1.55) to about 2,740 — that's the weekly average target. Protein is fixed at 144 g/day (1.8 g/kg) on both day types. Training days land at about 3,151 calories: 144 g protein, roughly 473 g carbs, and 76 g fat. Rest days come out to about 2,192 calories: the same 144 g protein, about 164 g carbs, and 106 g fat. Weight those across the week — four training days, three rest days — and the average comes back to the 2,740-calorie target.

Where This Approach Can Break Down

This is a starting framework, not a fixed prescription — real results depend on sleep, stress, and how consistently you can actually eat this way. A few things worth watching: stacking too many training days against too few rest days (say, six high-carb days against one low) can force that single rest day's calories very low once protein is held fixed, since there's less room left for carbs and fat to fill in. The calculator applies a floor so fat and carbs never go negative, but a very lopsided output is a sign to reconsider the split, not just accept it. Treat the protein number as a minimum rather than a ceiling, especially if you strength train regularly, and check with a doctor or registered dietitian before restructuring your intake around a weekly cycle if you have a metabolic or eating-related health condition.