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NHS guidance for formula-fed babies after the first week: roughly 150-200ml per kg per day until around 6 months, fed responsively; babies vary day to day and appetite is the better guide than the maths. Not medical advice: follow your midwife or health visitor, especially for newborns, premature babies or any feeding concerns.
What The Baby Formula Calculator Works Out
- Total per day: the NHS working guideline for formula-fed babies past the first week is 150 to 200ml per kilogram of body weight across 24 hours until around six months, so the calculator multiplies the weight by 150ml. A 5kg baby needs roughly 750 to 1,000ml a day.
- Per feed: the daily total divided by the number of feeds. Six feeds for a 5kg baby is 125 to 165ml a bottle. Newborns in the first days take far less (a newborn's stomach starts marble-sized) and from six months solids gradually take over, with formula falling toward 500 to 600ml a day.
- Typical range: the 150 to 200ml per kg band. It is a range, not a target: feed when hungry, stop when done, and expect growth-spurt days above the maths and sleepy days below it. Wet nappies, weight gain along the red book centiles and a content baby are the real dashboard.
- Weight in pounds (advanced): enter 11lb 4oz as 11.25 and the calculator converts to kilograms (1lb = 0.454kg).
- Guideline used (advanced): move the ml per kg figure anywhere within the 150 to 200 band, for example if your health visitor has suggested the higher end.
- Scoops per feed (advanced): UK first infant milks use one level scoop per 30ml of water, so the card rounds the feed up to whole scoops and shows the volume that makes. Never add an extra scoop or water down; the ratio is a safety matter, not a preference.
- Per feed in fluid ounces (advanced): bottle markings often show UK fluid ounces (28.4ml each) alongside millilitres.
- A tin lasts (advanced): a scoop holds about 4.4g of powder, so the daily volume converts to grams a day and the tin size (usually 800g, sometimes 700g or 900g) gives the days per tin, typically 7 to 9 for a 5kg baby.
- Formula cost (advanced): the tin price divided by the days it lasts, per week and per month. Supermarket own-brand first infant milk costs around GBP 9 to GBP 10 a tin against GBP 13 to GBP 16 for the big brands, and infant formula composition is regulated, so the difference is marketing. First infant milk is the only formula babies need for the first year; follow-on milks are optional. Make bottles fresh with water of at least 70C, cool to body temperature and use within two hours. Not medical advice.
Source and further reading: NHS: formula feeding guidance.