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About this tool
Daily fluid target while nursing, derived from milk output and feeding frequency rather than a flat one-size figure.
This calculator works out how much extra fluid breastfeeding adds to your day by rebuilding the figure from milk output rather than quoting a flat number. EFSA adds 700 ml of total water a day for lactation because average exclusive-breastfeeding output is about 800 ml of milk a day and human milk is roughly 87% water — 800 x 0.87 = 696 ml. Enter your stage, feeds per day and number of babies (or a measured pumped volume) and the increment scales with your actual production, on top of the 2.0 L/day adequate intake for adult women.
Open Breastfeeding Hydration Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Rebuilds EFSA's +700 ml from milk volume x 87% water, so the number moves with your output.
Stage and feeds per day change the milk estimate instead of everyone getting the same answer.
Also expressed as a glass at each feed, which is easier to act on than a daily litre figure.
About 2.7 litres of total water a day — the 2.0 L adequate intake for adult women plus EFSA's 700 ml lactation increment. Around 20% comes from food, so roughly 2.1-2.2 litres as drinks, more in hot weather or with a heavy milk supply.
No. Trials of forced fluid intake have not shown higher milk production, and drinking well beyond thirst does not help. Supply responds to frequent, effective milk removal; if supply is a concern, ask a lactation consultant or your health visitor rather than adding litres.
Roughly 750-800 ml a day during exclusive breastfeeding in the first six months, dropping to about 600 ml once solids start and lower again past a year. Individual output varies widely, which is why a measured pumped volume beats any average.
Oxytocin released during let-down triggers thirst, which is the body's way of covering the water leaving as milk — roughly 700 ml a day. Drinking to thirst, with a glass at each feed as a prompt, generally covers it. Persistent extreme thirst with frequent urination should be checked by a doctor.
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