Carb Cycling Calculator

What this calculator does

This tool turns a weekly average carbohydrate target into specific daily gram targets for high-carb, moderate-carb and low-carb days, based on how many of each day type you plan across the week. Enter your weekly average carb intake and how many high, moderate and low days you want (they must add up to seven), and the calculator returns the exact gram target for each day type plus a weekly plan table.

What carb cycling is

Carb cycling varies daily carbohydrate intake across the week instead of eating an identical amount every day — typically assigning higher carb intake to harder training days, when carbohydrate fuels performance and glycogen recovery most directly, and lower intake to rest or light-activity days, when the extra carbohydrate is less useful. The weekly average carb intake stays consistent even though daily amounts swing — this is the core idea distinguishing carb cycling from a flat daily macro target.

The calculation

This tool uses a 1.5× ratio for high days and a 0.5× ratio for low days, both relative to the moderate-day amount — a simple, commonly used ratio in carb-cycling coaching plans that creates a meaningful swing between day types without either extreme becoming unsustainable. Given your weekly average and day-type counts, the calculator solves for the moderate-day carb amount so that the weighted total across your chosen mix of high, moderate and low days exactly equals your weekly average multiplied by seven days. High and low day targets are then simply that moderate figure scaled by 1.5 and 0.5.

Why these specific ratios

Coaches and individual athletes reasonably use different high/low ratios depending on goals and how much day-to-day variation they want to manage — some use 2× and 0.5×, others use gentler swings. The 1.5×/0.5× split used here is a sensible middle-ground default: noticeable enough to matter for training performance and adherence, but not so extreme that low-carb days become difficult to sustain or high-carb days risk excess calorie intake.

Choosing which days are high, moderate or low

Most carb-cycling approaches assign high-carb days to the hardest training sessions in a week — heavy lifting days or long cardio efforts — so more fuel is available exactly when it's needed most, with low-carb days reserved for rest days or light activity. Moderate days typically bridge lighter training sessions. There's no single correct pattern; match your day types to your actual weekly training schedule rather than a fixed template.

A note on the numbers

Because the calculator solves backward from your weekly average, unusual day-count combinations (for example, only one or two high/moderate days against many low days) can produce a large single-day carb amount to keep the weekly average correct — this is mathematically expected and mirrors how a "refeed day" approach works in practice.

This tool gives a general estimate from a commonly used ratio-based approach, not personalized nutrition advice. Talk with a registered dietitian before making significant changes to your diet.