Carb cycling calculator.
This carb cycling calculator takes your maintenance calories, bodyweight and training week and gives a client two numbers: a high-carb day for training and a low-carb day for rest. Protein and fat stay steady, carbohydrate carries the swing, and the week still averages your fat-loss or muscle-gain target.
cycle the carbs
How big should the carb swing be?
The percentage is the gap between a high-carb and a low-carb day, measured against your average daily carbohydrate.
your carb day targets
high-carb day (4x/week)
2,265 kcal
- Protein: 160 g
- Carbs: 262 g
- Fat: 64 g
low-carb day (3x/week)
1,835 kcal
- Protein: 160 g
- Carbs: 154 g
- Fat: 64 g
the week averages your target
Weekly average target: 7 x 2,080 = 14,560 kcal/week.
Cycled plan: 4 x 2,265 + 3 x 1,835 = 14,565 kcal/week.
Any small difference is rounding to the nearest 5 kcal - the underlying carb split balances exactly.
Protein is set at about 2.0 g per kg of bodyweight and fat at about 0.8 g per kg, both held constant on every day - carbohydrate is the only macro that moves. Adjust protein upward on an aggressive cut, and treat the carb numbers as a starting structure to refine from check-in data.
the short answer
Carb cycling holds protein and fat steady and moves only carbohydrate: more on training days, less on rest days. This calculator starts from a weekly average (maintenance minus the goal, so 2,600 kcal at -20% is 2,080), sets protein near 2.0 g per kg and fat near 0.8 g per kg, and lets carbs fill the rest. For an 80 kg client that is 160 g protein and 64 g fat every day, leaving about 864 kcal of carbs as the daily average. A moderate 50% swing across 4 training days gives roughly 2,265 kcal high-carb days (262 g carbs) and 1,835 kcal low-carb days (154 g carbs) - and 4 x 2,265 + 3 x 1,835 is 14,565 kcal, the same week as 7 x 2,080 = 14,560 within rounding.
How carb cycling works - and why only carbs move.
Body composition is driven by the weekly calorie average, not by any single day. Carb cycling accepts that and asks a narrower question: given the week's calories are set, where should the carbohydrate land? The answer is to put it where training actually uses it - more carbs on the days a client trains hard, fewer on the days they mostly recover. The weekly total stays identical to a flat plan, which is why this calculator shows the week summed both ways: 7 x average, and high-carb days plus low-carb days. They always agree.
The macro logic is the standard one. Protein stays constant, set from bodyweight, because muscle repair and satiety needs do not take rest days off - recovery from a hard session runs 24 to 48 hours, straight through the next low day. Fat sits on a steady floor for hormone health and to keep meals satisfying. That leaves carbohydrate as the only lever that moves, because it is the fuel that powers hard training and refills muscle glycogen afterwards, so the extra calories on training days do the most good as carbs.
Who it suits: someone whose week genuinely varies - hard sessions on some days, very little movement on others. For them a flat carb number underfuels the big days and overfeeds the quiet ones, and shifting the carbs often makes a fat-loss phase easier to live with because training days still feel generous.
Who it does not suit: anyone who finds variable targets stressful - two carb numbers to hit is twice the mental load, and adherence beats optimisation every time. And it is not for a client with a history of disordered eating: day-to-day shifts in "allowed" carbs can feed exactly the preoccupation with food that a steady, boring target helps quiet. If that is your client, keep the target flat, say so kindly, and get qualified support involved where it is needed.
Two carb days per client, mapped to the training week.
In practice a coach runs this once per client per phase. Start from the client's maintenance and goal, set the swing that matches how different their days really are, and you have two targets: a high-carb day and a low-carb day, with protein and fat unchanged between them. Then map them to the program - the high-carb number goes on days with a scheduled session, the low-carb number on everything else. When the phase changes, rerun with the new maintenance figure; the shape of the week stays put.
Start clients on the mild swing and widen it only if the check-in data says the big days are still underfuelled or the low days are not moving the average. The moment a client reports that two carb numbers are stressing them out, collapse it back to the flat average - the week is identical either way, so nothing is lost.
The bottleneck was never the math - it is doing this for a whole client list and keeping every pair of numbers current. Inside Coachway, calorie and macro targets live on each client and can be set per weekday, then flow straight into their meal plan and their app, so a high-carb and low-carb split is an edit on the client, not a spreadsheet rebuild - you handle everything around one client from one tab.
If you are setting high-carb and low-carb days for a whole client list, see how fast it is when the targets live on the client.
No charge today - a card is required to start, and you can cancel anytime under Billing.Frequently asked questions.
What is a carb cycling calculator?
A carb cycling calculator turns your maintenance calories, bodyweight and training week into two daily targets: a high-carb day for training and a low-carb day for rest. Protein and fat stay steady from day to day, carbohydrate carries the swing, and the week still averages your goal calories - so a fat-loss or muscle-gain phase runs on the weekly total while each day matches food to activity.
How do you set high-carb and low-carb day targets?
Start from a weekly average - maintenance calories adjusted for the goal (this tool uses -20% or -10% for fat loss, 0% to maintain, or +10% for a lean gain). Hold protein at about 2.0 g per kg of bodyweight and fat at about 0.8 g per kg on both day types. Whatever calories are left become your average daily carbs, then split them: high days sit above the carb average, low days below, balanced so the week sums back to seven times the weekly average.
Why do protein and fat stay the same on every day?
Protein serves muscle repair and satiety, and both needs run around the clock - recovery from a hard session lasts 24 to 48 hours, straight through the next rest day - so protein is held constant from bodyweight. Fat is kept to a steady floor for hormone health and meal satisfaction. That leaves carbohydrate as the one lever that moves, which is exactly the point of carb cycling: put the fuel where the training is.
How much should carbs differ between a high day and a low day?
This calculator offers a mild, moderate or aggressive swing - roughly a 30%, 50% or 75% gap between your high-carb and low-carb days, measured against your average daily carbohydrate. Start mild and widen it only if check-in data says the training days are underfuelled or the rest days are not needed. A bigger swing is not better - it is only useful when a client can actually hit two different numbers without stress.
Does carb cycling burn more fat than a steady diet?
Not on its own. Fat loss is driven by the weekly calorie average, and this tool keeps that average identical to a flat plan. What cycling can improve is training quality on hard days, hunger management on low days, and adherence for people whose week genuinely varies. If a single steady target is easier for a client to follow, that is the better plan - the week is the same either way.
Who should not use carb cycling?
Anyone who finds shifting daily targets stressful, and any client with a history of disordered eating - moving numbers day to day can feed a preoccupation with food that a steady target avoids. Beginners who have not yet built the habit of hitting one consistent number are usually better served by a flat target first. Carb cycling is a refinement, not a starting point.
These targets are a starting structure, not a prescription - adjust to check-in data, and keep protein tied to body weight where you know it. This tool is general fitness information, not medical advice.
Get the weekly average right first: estimate maintenance with the TDEE calculator, check the baseline split with the macro calculator, cycle the total instead of the carbs with the calorie cycling calculator, and read the evidence-honest background in what is carb cycling.
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Open calculator ->Set high-carb and low-carb days for every client - from one tab
This calculator gives you the two numbers for one client. Coachway - built on knowledge from working with 150 online coaches over 6+ years - keeps calorie and macro targets on every client, set per weekday, and pushes them straight to their meal plan and app, so a carb-cycling phase is an edit, not an afternoon.
