RACE-WEEK FUEL · FREE TOOL
Carb loading calculator
Choose your event, enter your body weight and expected finishing time, and get grams of carbohydrate for the carb load, the race-morning meal, each hour of the race and the recovery after. For marathons, half marathons, triathlons, HYROX and long rides.
YOUR RACE-WEEK NUMBERS
Your carb load
Enter a body weight between 35 and 200 kg (77–440 lb) and a finishing time such as 4:15.
For 70 kg:
- 1Fuel-up, 36–48 h before the start: 560–840 g of carbohydrate a day (8–12 g/kg). Plait's default: about 700 g a day (10 g/kg) for 2 day(s), never more than 1.8 times your usual plan. That is roughly 14 portions of 50 g (table below).
- 1No carb load needed: for an event of about an hour or less, eat your usual meals the day before.
- 2Race-morning meal: 70–280 g of carbohydrate, 1–4 h before the start. Plait's default for your start: about 140 g (2 g/kg), 3 h before (around 05:00). For example:
- 1 × plain bagel (53 g)
- 1 × tbsp jam (14 g)
- 1 × banana (27 g)
- 1 × 250 ml glass of orange juice (26 g)
- 1 × tbsp honey (17 g)
- 3During the race: 30–90 g of carbohydrate per hour, about 120–360 g over your finishing time, from gels, chews or sports drink you have practised with.
- 4After: 20–40 g of protein and a carbohydrate-rich meal. If you train again within 8 h: 70–84 g of carbohydrate per hour for the first 4 h. The day after: about 350–490 g of carbohydrate.
Want these grams on your plate? Plait builds your week of meals from what your WHOOP or Garmin measured (Apple Watch in beta) and lays race week on top: fuel-up days, a timed race-morning meal and a recovery day, in weighed portions of real food.
Get a race-week plan from your watchHow many carbs should I eat when carb loading?
Short answer: For races longer than about 90 minutes, about 8–12 g of carbohydrate per kg of body weight a day for the 36–48 hours before the start: the ACSM joint position gives 10–12 g per kg per 24 hours, the ISSN 8–12 g per kg a day over 1–3 days. For a 70 kg runner that is about 560–840 g a day. For events of 60–90 minutes, 7–12 g per kg over the 24 hours before is enough; under an hour, eat a normal day and a carbohydrate-rich meal 1–4 hours before the start.
Carb loading by event
| Event | Typical time | Carb load (guideline) | Plait's default | During the race |
|---|---|---|---|---|
| Marathon | 4:00 | 8–12 g/kg a day for 36–48 h | 10 g/kg for 2 days | 30–90 g per hour |
| Half marathon | 2:00 | 8–12 g/kg a day for 36–48 h | 8 g/kg for 2 days | 30–60 g per hour |
| 10K | 0:55 | Not needed: a normal day, then a carbohydrate-rich meal before the start | Pre-race meal of about 1 g/kg | Not needed under about an hour |
| Ultra or trail run | 7:00 | 8–12 g/kg a day for 36–48 h | 10 g/kg for 2 days | 30–90 g per hour |
| Sprint triathlon | 1:20 | 7–12 g/kg a day for 24 h | 7 g/kg for 1 day | 30–60 g per hour |
| Olympic triathlon | 2:30 | 8–12 g/kg a day for 36–48 h | 8 g/kg for 2 days | 30–60 g per hour |
| Half-distance triathlon (70.3) | 5:30 | 8–12 g/kg a day for 36–48 h | 10 g/kg for 2 days | 30–90 g per hour |
| Full-distance triathlon (Ironman distance) | 12:00 | 8–12 g/kg a day for 36–48 h | 10 g/kg for 2 days | 30–90 g per hour |
| Road race or gran fondo | 4:00 | 8–12 g/kg a day for 36–48 h | 10 g/kg for 2 days | 30–90 g per hour |
| HYROX | 1:20 | 7–12 g/kg a day for 24 h | 7 g/kg for 1 day | 30–60 g per hour |
A marathon race week, day by day
| Day | What to eat |
|---|---|
| 6 days before | Usual meals Eat your usual training meals. Training is tapering, so you do not need extra food, and you do not need to cut carbohydrate either. |
| 5 days before | Usual meals Usual meals. Keep protein steady (about 1.4–2.0 g per kg a day). |
| 4 days before | Usual meals Usual meals. Practise your race-morning breakfast if you have not yet. |
| 3 days before | Usual meals Usual meals. Shop for the next two days: familiar, low-fibre carbohydrate such as white rice, pasta, bagels, white bread, potatoes without skin, juice and jam. |
| 2 days before | Fuel-up Fuel-up day 1 (the 36–48 h window starts): 8–12 g of carbohydrate per kg (your grams are in the calculator), spread over meals and snacks. Make room by trimming fat and fibre rather than adding huge meals. |
| 1 day before | Fuel-up Fuel-up day 2: the same target. Swap high-fibre foods for lower-fibre ones (white rice for brown, peeled potato, white pasta), keep dinner familiar and not too late, and drink normally. |
| Race day | Race day Race morning: 1–4 g of carbohydrate per kg, 1–4 h before your start. During: 30–60 g per hour, up to 90 g per hour beyond about 2.5 h, only from products you have tried in training. After: 20–40 g of protein with carbohydrate. |
| Day after | Recovery Recovery day: back toward your usual meals, carbohydrate around 5–7 g per kg, protein at your usual level. |
What 50 g of carbohydrate looks like
| Food | Serving | Carbohydrate per serving | For about 50 g |
|---|---|---|---|
| cooked white rice | 150 g | 42 g | 175 g |
| cooked pasta | 150 g | 46 g | 160 g |
| boiled potato, no skin | 200 g | 40 g | 250 g |
| plain bagel | 1 bagel | 53 g | 0.9 × bagel |
| white bread | 1 slice | 15 g | 3.3 × slice |
| crisp rice cereal | 1 30 g bowl | 26 g | 1.9 × 30 g bowl |
| banana | 1 banana | 27 g | 1.9 × banana |
| orange juice | 1 250 ml glass | 26 g | 1.9 × 250 ml glass |
| jam | 1 tbsp | 14 g | 3.6 × tbsp |
| honey | 1 tbsp | 17 g | 2.9 × tbsp |
| raisins | 1 small handful (30 g) | 24 g | 2.1 × small handful (30 g) |
| rice cake | 1 rice cake | 7 g | 7.1 × rice cake |
| sports drink | 1 500 ml bottle | 32 g | 1.6 × 500 ml bottle |
How race week works in Plait
Plait sets your daily calories from what your watch measured (WHOOP and Garmin; Apple Watch in beta) and builds a week of meals with weighed portions.
Tell the coach chat about your race: the type, the date, your start time and your expected finishing time. Code, not the AI, turns that into a day-by-day plan: fuel-up days, a timed race-morning meal and a recovery day, from the guideline ranges above or the grams per kg you choose.
Each day stays tied to your own plan: carbohydrate and calories at most 1.8 times your usual day on the last fuel-up day, protein kept, lower-fibre swaps the day before and on race day, and at most one starch per meal. A weight-loss plan is not turned into a 4,000-calorie day.
Free: create the event, see the whole day-by-day proposal and the countdown. Pro: the meals themselves change on those days (carbohydrate and fat portions; protein stays). Nothing changes until you apply it.
Plait only knows the training and races you tell it about. Watch calorie figures are estimates.
Get your race-week plan from your watch
Connect WHOOP or Garmin (Apple Watch in beta). Plait builds your weekly meals from what your watch measured, then lays race week on top.
Get your race-week plan from your watchRacing once? The Race Fuel Pass
$19 one time, for one race: your meals follow your training until race day, then the carb load, race morning and the recovery week. No subscription.
Get the Race Fuel PassQuestions
When should I start carb loading for a marathon?
36–48 hours before the start, which in practice means the two days before the race: for a Sunday marathon, Friday and Saturday. Earlier in race week, eat your usual training meals. Plait's race week uses 10 g per kg for those two days, capped relative to your usual plan.
Do I need to carb load for a half marathon?
It depends on your finishing time. Under about 90 minutes, a 24-hour fuel-up of 7–12 g per kg is enough. Longer than that, the guideline is the 36–48 hour window at 8–12 g per kg. Plait's default for 90–150 minutes is 8 g per kg for one day, or two days if you expect to take 2 hours or more.
How many carbs per hour during a race?
30–60 g per hour for efforts of 1–2.5 hours, and up to 90 g per hour beyond about 2.5 hours (ACSM joint position; IOC consensus). The higher amounts are absorbed best from glucose–fructose mixtures (ACSM); practise them in training first. Under about 45 minutes no carbohydrate is needed during the race; up to about 75 minutes, small amounts or a carbohydrate mouth rinse are enough.
Should I carb load for HYROX or a sprint triathlon?
Not marathon-style. Events of 60–90 minutes call for a 24-hour fuel-up of 7–12 g per kg, not two days. HYROX is intermittent running and station work, so Plait's race week never gives it more than one fuel-up day at 7 g per kg, whatever finishing time you enter.
How do I eat that much carbohydrate without feeling stuffed?
Spread it over meals and snacks, lean on familiar low-fibre foods (white rice, pasta, bagels, white bread, peeled potatoes, juice, jam) and trim fat and fibre to make room instead of adding huge meals. The table below shows what 50 g of carbohydrate looks like.
Does Plait plan race week for me?
Tell Plait's coach chat about your race and it computes a day-by-day plan: fuel-up days, a timed race-morning meal and a recovery day. Free accounts see the whole plan and the countdown; with Pro the meals themselves change on those days. Nothing changes until you apply it.
Sources
- Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Med Sci Sports Exerc 2016;48(3):543–568 (ACSM joint position, Table 2). pubmed.ncbi.nlm.nih.gov
- Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. J Sports Sci 2011;29 Suppl 1:S17–S27 (IOC consensus conference on nutrition for sport). pubmed.ncbi.nlm.nih.gov
- Kerksick CM et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr 2017;14:33 (8–12 g/kg/day to maximize glycogen stores). pubmed.ncbi.nlm.nih.gov
- Jäger R et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr 2017;14:20 (1.4–2.0 g/kg/day). pubmed.ncbi.nlm.nih.gov
Race-week guides
- What to eat the week before the NYC Marathon
- What to eat the week before the Philadelphia Marathon
- What to eat the week before the CIM
- What to eat the week before the Valencia Marathon
- What to eat the week before the Honolulu Marathon
- HYROX nutrition: what to eat in training and race week
Check the gap between your watch and a calorie formula · Garmin macro calculator · WHOOP macro calculator · All race-week guides