Carb Loading Calculator

Body weight:

Use current race-week body weight; changing the unit preserves the physical quantity.

Expected event duration:

Enter expected moving or competition time, from 0.25 to 48 hours.

hours

Planning protocol:

Choose a preset, then adjust the target or days if your sports dietitian has individualized the plan.

Daily carbs:

{{ formatNumber(target_gkg, 1) }} g/kg/day

Choose 3–12 g/kg/day. Values outside 10–12 are shown as individualized or general-fueling targets, not the standard loading range.

Loading window:

Use two days for the published 36–48 hour loading protocol.

Planning blocks per day:

Count meals, snacks, and drink windows; the output is an even arithmetic starting point.

Pre-event meal target:

{{ formatNumber(pre_event_gkg, 1) }} g/kg

This is calculated separately from the loading-window total.

Planned drink share:

{{ drink_share_pct }}%

The neutral default is 0%; only use a drink share you have tolerated in training.

Gram display:

Choose whole grams or one decimal place without changing the plan.

Measure	Value	Interpretation	Copy
{{ row.label }}	{{ row.value }}	{{ row.note }}

Block	Total	Food	Drinks	Copy
{{ row.label }}	{{ row.total }}	{{ row.food }}	{{ row.drink }}

Check	Status	Action	Copy
{{ row.label }}	{{ row.status }}	{{ row.action }}

Endurance performance can suffer when muscle and liver glycogen run low. Carbohydrate loading raises carbohydrate availability before a long event by pairing a high intake with reduced training. It is a short race-week strategy, not an everyday diet and not a substitute for fueling during the event.

Event duration is the first filter. Published loading guidance commonly targets sustained or intermittent exercise lasting more than 90 minutes. Shorter events may need normal daily fueling and a familiar pre-event meal instead of 10 to 12 grams per kilogram per day. Pace, terrain, heat, repeated surges, and the athlete's history can still affect whether a longer event benefits.

Carbohydrate planning choices by event context
Situation	Likely focus	Important caution
Event not over 90 minutes	Normal daily fueling and a practiced pre-event meal	A full load can add food volume without matching the event's likely need.
Event over 90 minutes	Consider the 36 to 48 hour loading range	High targets still need a taper and foods that have been tolerated before.
Very high daily grams	Spread intake across meals, snacks, and familiar drinks	Arithmetic does not guarantee digestive comfort or adequate overall nutrition.

Grams per kilogram per day scales the plan to body mass. A 55 kg runner and a 90 kg cyclist can use the same relative target but receive very different daily totals. Loading days determine the full-window total, while the pre-event meal is a separate calculation and should not be silently added to that window.

Food choice and timing decide whether the number is practical. Several smaller eating opportunities can be easier than a few oversized meals. Lower-fiber, lower-fat familiar foods may reduce bulk for some athletes, and drink carbohydrate can help only when its concentration and volume have already been tolerated in training.

The plan is informational, not a nutrition prescription. Diabetes, gastrointestinal or kidney disease, pregnancy, prescribed diets, medication use, and a history of disordered eating require guidance from a qualified clinician or sports dietitian before an aggressive loading change.

How to Use This Tool:

Choose a protocol that fits the expected event, then turn the daily total into eating opportunities you can actually rehearse.

Enter current race-week Body weight in kilograms or pounds and the expected moving or competition time under Expected event duration.
Choose a Planning protocol. The standard and high presets use 10 or 12 g/kg/day for two days; the top-up uses 7 g/kg/day for one day.
Adjust Daily carbohydrate target or Loading window only when an individualized plan calls for a different value.
Set Planning blocks per day to the number of meals, snacks, and drink windows you expect to use. The split is even across 3 to 8 blocks.
Choose the separate Pre-event meal target. Add a Planned drink share only when that percentage has been practiced in training.
Review Loading plan, Meal blocks, and Planning checks. Correct the input named in any warning before relying on the gram totals.

Interpreting Results:

Daily target is body weight in kilograms multiplied by the selected g/kg/day value. Window is that daily target multiplied by the number of loading days. The Pre-event meal estimate uses its own g/kg value and remains separate from both.

Published range means the target is from 10 through 12 g/kg/day and the window is exactly two days.
Custom window means the target is within 10 to 12 g/kg/day but the window is not two days.
Individualized target means the daily value is outside 10 to 12 g/kg/day.
General fueling range appears when event duration is 90 minutes or less; Loading duration fit requires more than 90 minutes.

Meal blocks are equal arithmetic shares, not menus or tolerance limits. A clean planning check does not prove that the volume, fiber, sweetness, or drink concentration will be comfortable. Verify the daily total against a practiced race-week food plan.

Technical Details:

The calculation normalizes pounds to kilograms, applies a daily grams-per-kilogram target, and then allocates the result. Event duration does not change the gram arithmetic; it selects planning cues that indicate whether the event is over the guideline's 90-minute duration boundary.

Formula Core:

One body-mass-scaled daily target drives the loading total and the food-and-drink allocation. The pre-event meal is calculated independently.

\begin{array}{lcl} W_{kg} & = & W_{lb} \times 0.45359237 \\ C_{day} & = & W_{kg} \times G_{day} \\ C_{window} & = & C_{day} \times D \\ C_{block} & = & \frac{C_{day}}{B} \\ C_{drink} & = & C_{day} \times p / 100 \\ C_{food} & = & C_{day} - C_{drink} \\ C_{pre} & = & W_{kg} \times G_{pre} \end{array}

W is body weight, G_day is the target in g/kg/day, D is 1 to 4 loading days, B is 3 to 8 meal blocks, p is drink share from 0% to 50%, and G_pre is the separate pre-event target from 1 to 4 g/kg.

A 70 kg athlete at 10 g/kg/day receives 700 g per day. Two days produce a 1,400 g loading-window total. Six even blocks are about 116.7 g each, and a separate 2 g/kg pre-event meal is 140 g. Whole-gram display rounds those figures for presentation without changing the underlying plan.

Rule Core:

Carbohydrate loading protocol and boundary rules
Rule	Exact boundary	Planning result
Weight after conversion	35 to 250 kg, inclusive	Values outside the supported range are rejected.
Full-load duration cue	Event duration > 1.5 hours	Marks the event as over 90 minutes.
Pre-event duration cue	Event duration > 1 hour	Places a 1 to 4 g/kg meal about 1 to 4 hours before exercise in the cited longer-than-60-minute context.
Published loading range	10 ≤ target ≤ 12 g/kg/day and exactly 2 days	Matches the modeled 36 to 48 hour protocol.
Short-event warning	Duration ≤ 1.5 hours and target ≥ 10 g/kg/day	Flags a full-load target for a short event.
Custom-window warning	Days not equal to 2 and target ≥ 10 g/kg/day	Separates a high target from the published two-day window.

Every loading day repeats the same daily target. Every meal block receives the same share. The day allocation and block rows split that amount into food and drink with the chosen percentage; they do not model menus, absorption, glycogen storage, or energy balance.

Accuracy and Health Notes:

The result organizes carbohydrate targets; it does not measure glycogen stores, predict performance, or diagnose nutrition needs. Body mass, taper quality, training load, event intensity, prior diet, heat, altitude, and gastrointestinal tolerance can change the usefulness of the same number.

Use familiar foods and drinks, especially near the upper 10 to 12 g/kg/day range.
High fat, protein, or fiber can make a carbohydrate target harder to tolerate even when the grams are correct.
Seek qualified guidance for medical conditions, pregnancy, prescribed diets, medications, or disordered-eating history.

Worked Examples:

High load with a practiced drink share

A 100 kg athlete planning a four-hour event chooses 12 g/kg/day for two days, four blocks per day, a 3 g/kg pre-event meal, and a practiced 25% drink share. The plan gives 1,200 g per day and 2,400 g across the loading window. Each block is 300 g total, split into 225 g from food and 75 g from drinks; the separate pre-event meal is 300 g. Those large servings make tolerance review essential even though the settings match the published loading band.

References:

Nutrition and Athletic Performance, Academy of Nutrition and Dietetics, Dietitians of Canada, and American College of Sports Medicine, 2016.
Nutrition strategies for the marathon: fuel for training and racing, Sports Medicine, 2007.
Role of nutrition in performance enhancement and postexercise recovery, Open Access Journal of Sports Medicine, 2015.