Free tool
Cycling Fuel Calculator.
Build a practical fuelling plan for your next ride: what goes in the bottles, what needs to come from gels or chews, and when to take it.
The calculator recommends the bottle mix after it sees the ride. Start from your current fuelling level, test the next sensible step, and adjust based on how your body responds.
What do I put in my bottles for this ride?
Use this to build a practical bottle mix for your next ride. Start from your current fuelling level, test the next sensible step, and adjust based on how your body responds.
Ride details
Use feel first. If you know CP, easy is usually under roughly 75% CP, moderate-to-tempo is roughly 75-90%, hard sits near that upper edge, and race/surging covers repeated climbs, attacks, or group-ride changes.
Your current fuelling
Conditions
Temperature mainly changes fluid, sodium priority, and pacing caution. It does not automatically mean chasing a bigger carb number.
Bottle setup
Choose concentrated if you want the bottles to cover more of the target. Choose easier to drink if sweet or heavy bottles are not tested; the remainder moves to gels, chews, food, or refill mix.
Build the bottles first.
Add your ride details and the plan updates live. The useful answer is what goes in each bottle, what still needs to come from food or refills, and whether the target is a sensible next test.
Use it in your agent
Bring the products you already use.
SEMIPRO Ride Fuelling is now available through our public MCP. Give your agent the ride duration, the work you are doing, your current tested tolerance, and the carb amount in your gels, bottles, chews or food. It will return an exact carry pack and timing guide.
Connect SEMIPRO IntelligenceA plan that learns what works.
The free calculation is the start. The useful persistent layer will remember your tested products and tolerance, compare planned with actual intake, capture gut comfort and late-ride response, and make the next strategy better.
Product recommendations will stay neutral. Retailer commission will never change the fuelling calculation or ranking.
Use the result as your next test.
This calculator is built around execution. First it works out the ride demand, then it shows what the bottles cover, what still needs to come from gels, chews, food, or refills, and how to space that across the ride.
Do not jump straight to an extreme intake because you saw a pro do it. If you have not tested the target in training, do not use it for the first time on race day.
The best fuelling plan is not the cheapest one, the most expensive one, or the biggest carb number. It is the one you have tested, can tolerate, can carry, and can execute when the ride gets hard.
If the bottles do not cover the full target, use the remaining carbohydrate number to choose gels, chews, food, cafe stops, or refill mix. Check the label before the ride, not when you are already tired.
Fuelling is easier when the training matches the ride.
The bottle plan is only one part of execution. If you want training that matches your goals, fatigue, available time, race demands, and fuelling practice, explore SEMIPRO training plans or coaching.
The science behind the calculator.
This is a starting point, not a rule. More carbohydrate is not automatically better if you cannot tolerate it.
Carbohydrate and ride demand
Carbohydrate helps support hard and long riding, especially as duration and intensity rise. The calculator scales targets with ride demand instead of treating every ride the same.
Reference: Thomas, Erdman & Burke 2016; Jeukendrup 2014.
Intensity is a guide, not a cage
Fixed percentages are useful shorthand, but they do not perfectly describe what is happening inside every rider. That is why the calculator uses simple intensity choices, with Critical Power anchors only as a guide.
Reference: Jamnick et al. 2020; SEMIPRO coaching canon.
Heat changes execution
Heat mainly changes fluid needs, sodium priority, perceived effort, and pacing. The same power can cost more in hot conditions, so the calculator treats heat as an execution warning rather than a reason to blindly increase carbohydrate.
Reference: Wingo et al. 2005; Tyler et al. 2016; Maunder et al. 2021.
Sugar, maltodextrin, glucose and fructose
Table sugar provides glucose and fructose after digestion, so it is the default for normal targets. At 90 g/h and above, the calculator switches to a 1:0.8-style mix because high-carbohydrate fuelling depends more on glucose/fructose transport and gut tolerance.
Reference: Jeukendrup 2010; Jeukendrup 2014.
Why 100-120 g/h is not the default
Ultra-high carbohydrate intake, defined as more than 90 g/h, is gaining attention in endurance sport. But the evidence does not support treating it as the default for every athlete. Use higher targets as something to test, not something to copy blindly.
Reference: Plews, Booth, Krieger & Maunder 2026.
Sodium: test and target, or season to taste
Sodium needs vary widely. For some rides, seasoning to taste is enough. For long, hot, sweaty, or high-fluid-intake rides, sodium may need to be more targeted.
Reference: McCubbin 2023.
This calculator is for general education and planning. It does not replace individual advice from a qualified sports dietitian or medical professional. If you have diabetes, kidney disease, a history of hyponatraemia, eating disorder risk, significant GI issues, or medical concerns, seek individual advice.