How to Read a Baby Scale and Check It Is Accurate

To read a baby scale, switch it on and wait for 0, tare any towel, lay the baby on its back in the middle of the tray and note the number once it stops changing. On a scale that reads in 5 g steps, such as the Venus EBS-KS-9090, 3.455 kg means 3,455 g. WHO guidance is to weigh babies naked where possible.

Reading a digital baby scale step by step

Most digital models in Omace's baby weighing scale range work the same way. The steps below follow the Venus EBS-KS-9090 infant weighing scale, which weighs up to 20 kg in 5 g steps and shows grams, kilograms or pounds. The Venus EBS baby scale series is a Legal Metrology approved model in accuracy class III; the approved 30 kg model has a minimum load (Min) of 100 g and a verification interval (e) of 5 g.

1. Use a firm, level surface. A table or the floor works; a bed or sofa does not.
2. Switch on and wait for 0. Do not touch the tray until the display settles.
3. Check the unit. Press the unit key until the display shows the unit your doctor's chart uses, usually kilograms.
4. Tare the towel. Lay a thin towel or blanket on the tray and press Tare so the display returns to 0.
5. Lay the baby down. Place the baby on its back in the centre of the curved tray, with one hand close by.
6. Wait for a steady number. A changing number means the baby is moving. Wait until it holds, then write it down with the unit.

A wriggling baby is easier to weigh on a scale with a hold key. The Ace ICDS-MBS-KS-810 digital baby weighing scale locks the reading even when the baby moves, reads in 10 g steps and works as an adult scale up to 100 kg with the tray removed.

What the numbers mean: grams, kg and pounds

The last digit tells you the step size. A 5 g scale ends in 0 or 5, as in 3.455 kg. A 10 g scale always ends in 0, so 3.46 kg is 3,460 g.

Pounds cause the most mistakes. NIST's conversion tables put one pound at 453.6 g and one ounce at 28.35 g, so 16 ounces make a pound. A display reading 7.6 lb is a decimal, not 7 lb 6 oz, and the two differ by about 100 g.

The WHO growth charts your paediatrician uses are in kilograms, so record the weight in kg or grams and keep the same unit every time.

Reading a dial or spring baby scale

Mechanical baby scales need no battery: the baby lies in a sling that hangs under the dial. Omace sells the Venus CHS-25 manual circular baby hanging scale for babies and toddlers up to 25 kg, and the Venus HSTB-5 spring balance for newborns up to 5 kg. Both read in 100 g steps and have a zero adjust. The CHS-25 dial is numbered every 1 kg, labels each half kilo (0.5, 1.5 and so on) and has a small mark for every 100 g. Its face is marked class IIII, Max 25 kg and Min 1 kg, the smallest load it should weigh. The Venus CHS and HSTB series are Legal Metrology approved models in accuracy class IIII.

1. Hang the scale from a strong hook, or hold it, so the dial is at your eye level.
2. With the empty sling hanging, turn the zero-adjust knob until the pointer sits exactly on 0. On the CHS-25 the knob is on top, beside the hook. If a scale has no zero adjust, note the empty reading and subtract it from the baby's weight.
3. Put the baby in the sling, keep a hand under the baby and let the swinging stop.
4. Read the dial straight on. Looking from the side shifts the pointer against the marks.
5. Count the small marks after the last number to get the reading. On the CHS-25 each small mark is 100 g, so a pointer three marks past 4 reads 4.3 kg. Write it down in kg.

A dial cannot show steps as fine as a digital tray, so it suits occasional checks better than close tracking of small gains.

How to weigh a baby at home

The WHO regional Child Growth Monitoring technical guide sets out the clinic method, and it works at home too. Babies should ideally be weighed naked. If that is not possible, weigh the baby in a clean nappy and subtract the weight of a similar nappy, or use the scale's tare.

The guide records an infant's weight to the nearest gram on digital scales that allow tared weighing. Without an infant scale, a parent can stand on a digital adult scale, tare it, then take the naked baby in their arms, and the display shows only the baby. The Venus EPS-05 mother and child weighing scale and the Venus EPS-09 (M) do this in mother-and-child mode: the mother weighs herself, steps off, picks up the baby and steps on again, and the scale shows the baby's weight on its own. It is quick and needs no separate baby scale. The EPS-05 reads in 100 g steps, so it suits monthly checks better than tracking small gains.

• Same time of day. Weigh before a feed and at the same time, so a full stomach does not look like growth.
• Same scale. Two scales rarely read exactly alike, so mixing home and clinic readings blurs the trend.
• Not too often. The NHS advises weighing a healthy baby no more than once a month up to 6 months, and once every 2 months from 6 to 12 months.
• Safety first. Never leave a baby alone on the scale, even for a second.

How to check a baby scale is accurate

Check a baby scale against something whose weight you know. Certified test weights are best. At home, use an item weighed first on a scale you trust, or a sealed 1 kg pack of rice or sugar, remembering that the packet itself adds a few grams.

1. Zero. Switch on with the tray empty. It should show 0, and return to 0 each time you lift the weight off.
2. Known weight. Place the weight in the centre and compare. On a 5 g scale, a match within one or two steps is good.
3. Ends of the tray. Move the same weight to each end of the tray. The reading should not change; if it does, one side of the scale is reading wrong.
4. Repeat. Weigh the same item five times. Readings that jump around point to a weak battery or a soft surface.
5. A heavier check. Repeat with a weight close to your baby's, such as 4 or 5 kg, because a scale can be right at 1 kg and wrong at 5 kg.

Scale standards use the same tests. OIML R 76, the international recommendation for non-automatic weighing instruments, tests a scale at several loads, with the load placed off-centre, and with repeated weighings.

Clinics check more often: the WHO growth monitoring guide asks for measuring equipment to be checked and calibrated regularly, preferably weekly. If a home scale stays off after new batteries, stop using it for tracking. The full home method is in how to calibrate a digital weighing scale.

Is the reading normal? Look at the growth curve

One reading means little; the curve over weeks is what a doctor looks at.

• The NHS says it is normal for babies to lose some weight in the first few days after birth, and most are at or above their birthweight by 3 weeks.
• The WHO defines low birth weight as a weight at birth of less than 2,500 g.
• The WHO weight-for-age standards give separate charts for boys and girls from birth to 5 years.
• The Indian Academy of Pediatrics recommends the WHO standards for assessing the growth of children under 5.

A home scale is a weighing device, not a diagnostic tool. A paediatrician should assess your baby's growth, and sooner if your baby is not back to birthweight by 3 weeks or the weight stops rising. For typical gains month by month, see how much weight a baby should gain.

Baby scales compared: steps, capacity and price

A digital tray with 5 g or 10 g steps suits regular tracking at home; a dial or spring scale suits occasional checks. For a fuller comparison, read how to choose a baby weighing scale.

Omace Brands Private Limited has made and supplied weighing scales in India since 1994. Every scale is tested before dispatch, the company holds CE, ISO 9001 and ISO 13485 certifications, and scales bought from the Omace store carry a 2-year warranty on manufacturing defects. More about Omace. Omace scales are made in India. As a manufacturer, Omace Brands Private Limited holds ISO 9001:2015, ISO 13485:2016 and EU MDR quality certificates, and CE and US FDA compliance certificates; each is listed with its certificate number on the Omace certificates page.