Water intake calculator: how much to drink a day for your weight
Work out how much water you need a day for your weight, how much of it to drink and how much to add for exercise. If you weigh yourself before and after training, we also tell you how much you sweat.
Total water: 30 to 35 ml per kilo of body weight, a widely used rule of thumb for adults on a rest day in a temperate climate.
To drink: about 80% of that total. The rest comes from food and from your own metabolism.
Exercise: half a litre is added for every hour, or one litre in hot weather or with heavy sweating. It is a cautious estimate: sweat rates vary a lot from one person to another, so it is best to measure yours.
What EFSA recommends
The European reference is the opinion of the European Food Safety Authority (EFSA, 2010), which sets an adequate intake of total water, counting both what you drink and what comes from food:
Adequate intake of total water for adults according to EFSA (2010)
Group
Total water per day
Of which, roughly, from drinks
Adult women
2.0 litres
About 1.6 litres
Adult men
2.5 litres
About 2.0 litres
Pregnancy
2.3 litres
About 1.8 litres
Breastfeeding
2.6-2.7 litres
About 2.1 litres
The calculator shows the reference for your sex alongside the weight-based figure. For people of average weight the two numbers are close; for very heavy or very light people, the weight-based figure moves further away.
How much water to drink when you train
The position stand of the American College of Sports Medicine (Sawka and colleagues, 2007) has one central goal: not to lose more than 2% of your body weight through dehydration during exercise, because beyond that point performance suffers. As sweat rates vary a lot between people, it recommends individual plans and estimating your sweat loss by weighing yourself before and after training.
How to measure your sweat rate
Weigh yourself without clothes just before training.
Train and note how much you drink.
Dry off and weigh yourself again without clothes.
Enter the figures in “Work out your sweat rate”: each kilo lost is roughly a litre of sweat.
According to EFSA, about 2.0 litres of total water a day for women and 2.5 for men, of which around 80% comes from drinks. By weight, 30 to 35 ml per kilo on a rest day.
Does water from food count?
Yes. Around 20% of total water comes from food, especially fruit, vegetables, dairy and soup. That is why the figure to drink is lower than the total water figure.
How much water should I drink when I train?
Enough not to lose more than 2% of your body weight in the session, according to the American College of Sports Medicine (2007). The way to know how much you sweat is to weigh yourself without clothes before and after training.
Can you drink too much water?
Yes. In very long efforts, drinking much more than you sweat can lower blood sodium, and some kidney or heart conditions require limiting fluids. Otherwise, drinking to thirst is a good day-to-day guide.
Calories and protein supply the fuel; training decides what you do with it. Generate a free routine built around your goal, your level and your equipment.
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on dietary reference values for water. EFSA Journal. 2010;8(3):1459.
American College of Sports Medicine, Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine & Science in Sports & Exercise. 2007;39(2):377-390.
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RoutineYour personalized routine
RIRReps in Reserve — how close to failure
RIR tells you how many reps you have left in the tank when you finish a set. RIR 2 means you could do 2 more reps before reaching failure. It's a more precise way to control intensity than using a fixed percentage of your max.
Example: If you do 10 reps of bench press with RIR 2, you could have done 12 at that moment. It's not an exact number — listen to your body.
VolumeTotal sets and reps
Volume is the total work done per muscle group per week (sets × reps × weight). For hypertrophy, 10–20 effective sets per muscle per week is recommended. Your routine adjusts this based on your level and available days. Each set counts in full for the exercise's main muscle and as half for the ones that assist: 4 sets of bench press are 4 for chest and 2 for triceps and shoulders.
Example: 4 sets of bench press + 3 sets of flyes = 7 sets for chest in that session. The weekly total determines how much the muscle grows.
FrequencyDays and weekly structure
Example: With 3 days/week, Full Body is used to train each muscle 3 times. With 4–5 days, muscle groups are split (Push/Pull/Legs or similar).
ProgressionHow to progress week by week
Progression is the most important principle in training. Your body adapts, so you need to give it a greater stimulus each week. The main ways are: adding weight, adding reps, or adding sets.
Tip: When you can hit the top of the rep range (e.g. 12) with good form and RIR 2, add 2.5–5 kg in the next session.
⚠️ You train at your own risk. Suggested loads are guidance only: increase them only if your technique is solid and pain-free. This does not replace advice from a medical professional or trainer. If you feel pain or get injured, stop and consult a specialist.
