What to drink and eat during exercise
How much water, carbs and salt per hour, and when to take them. Then watch your session play out, minute by minute, with or without drinking.
Water per hour
Carbs per hour
Salt per hour
Your session
Your session, minute by minute
Try another temperature
How it’s calculated
- The calculation is the Cadevia app’s own (the same one its coach uses for your sessions). Anything this tool adds is marked “added by this tool”.
- Water per hour = what you sweat: 0.8 L per hour for easy running or trail running, 1.3 for hard running, 1.2 for hard trail running, 0.6 for easy cycling, 1.0 for hard cycling (sweat-rate prediction equations, Journal of Applied Physiology, 2024; 1 L = 33.8 fl oz). “Steady” counts as easy for water: the app only counts a session as hard above 75 load points per hour, roughly your half-marathon pace. The feels-like temperature multiplies that figure: × 0.85 below 10°C (50°F), × 0.95 up to 18°C (64°F), × 1 up to 24°C (75°F), × 1.15 up to 28°C (82°F), × 1.3 up to 32°C (90°F), × 1.45 above that; with no answer, × 1. Rounded to 50 ml, never less than 400 ml (13.5 fl oz) or more than 1 L (34 fl oz) per hour (American College of Sports Medicine guidance, 2007). Triathlon counts as cycling, as in the app.
- “Do you sweat a lot?” (added by this tool): “yes” puts your sweat rate one standard deviation above the endurance-athlete average, i.e. × 1.45 (Barnes et al., Journal of Sports Sciences, 2019: 1.28 ± 0.57 L per hour across 1,303 athletes). “About average” and “I don’t know” keep the average.
- Carbs per hour depend on duration: none under 1 h 15 min; from 1 h 15 min to 1 h 30 min, none if it’s easy, 20–30 g otherwise; 30–60 g up to 3 h; 60–75 g up to 6 h; 60–90 g beyond that. But never more than your stomach knows: 20 g per hour if you never eat or only drink water, 30 if you eat sometimes, 60 if you have your routine. You build up in steps (20, 30, 45, 60, 75, 90 g), keeping a step once it has gone down fine twice. Duration benchmarks: Jeukendrup (Sports Medicine, 2014) and Burke et al. (Journal of Sports Sciences, 2011), made progressive by the Cadevia coach.
- When: a drink every 20 min on foot, every 15 min on the bike (the drink reminders on the Cadevia watch app; the NATA advises about 200 ml, or 7 fl oz, every 15 to 20 min). A serving of about 22 g of carbs (a gel or half a bar), spaced to hold your hourly rate, never less than 20 min apart. Each serving sits in the middle of its interval (added by this tool): the first comes early, the last before the finish, and the total follows your hourly rate. In a triathlon, nothing during the swim: take on the bike what the swim made you skip.
- Salt: 500–800 mg of sodium per liter you drink below 10°C (50°F), 500–1,000 from 10 to 20°C (50–68°F), 800–1,200 from 20 to 27°C (68–81°F), 1,000–1,500 above that (Cadevia coach benchmarks, top of the range when it’s hot), multiplied by the water you drink per hour, rounded to 50 mg. 1 g of salt = 400 mg of sodium (EU labeling rule: salt = sodium × 2.5). A 17-oz bottle is half a liter: half these amounts.
- Water loss (added by this tool): what you sweat minus what you drink, as a percentage of your weight (1 L ≈ 1 kg). From 2%, endurance performance drops; beyond 3%, the risk of heat illness climbs (National Athletic Trainers’ Association, McDermott et al., Journal of Athletic Training, 2017, recommendation 4).
- After the finish (added by this tool): drink back 1.25 times what you’re short (the American College of Sports Medicine advises 125 to 150%: some of it leaves in your urine). The app applies the same rule to your whole day.
- The limits: these are averages. Weigh yourself before and after a session to know your real loss (1 kg lost ≈ 1 L; 1 lb lost ≈ 15 fl oz). Never drink more than you lose: drinking too much dilutes the sodium in your blood (NATA, 2017). On race day, nothing new: only what you’ve tested in training.
Frequently asked questions
How much should I drink per hour while exercising?
What you sweat, between about 14 and 34 fl oz (400 ml to 1 liter) per hour: about 27 fl oz on an easy run and 20 fl oz on an easy ride, more when it's hard or hot (American College of Sports Medicine guidelines).
How many carbs per hour?
None for the first 1 hr 15 min. Then 30 to 60 g per hour up to 3 hours, 60 to 75 g up to 6 hours and up to 90 g beyond, never more than your gut is used to. Build up step by step in training, never on race day.
Do I need salt during exercise?
Yes, as soon as you drink a lot: 500 to 1,500 mg of sodium per liter you drink (about 250 to 750 mg per 17 oz bottle), depending on the heat. The tool gives it in grams of salt per hour.
When does dehydration start to hurt performance?
Around 2% of body weight lost; beyond 3%, the risk of heat illness rises (National Athletic Trainers' Association, 2017). The tool's “Without drinking” view shows when you get there.