What is a normal bilirubin in a newborn?

It depends on age in hours. In term infants the typical upper limit of physiological jaundice rises to ~256 µmol/L by days 3–5, then declines. It’s a guide, not a treatment threshold — that’s set by a doctor.

When is newborn jaundice dangerous?

Concerning signs: jaundice in the first 24 hours, rapid rise, jaundice in a preterm baby, lasting beyond 2–3 weeks, lethargy and poor feeding. These need urgent medical review.

Does this calculator tell me if phototherapy is needed?

No. Phototherapy thresholds are calculated only by a doctor using nomograms accounting for age in hours, gestational age, weight and risk factors. The calculator is a reference guide.

Why are norms different for preterm babies?

A preterm liver is even less mature and the risk of complications is higher, so bilirubin limits are lower and decisions are made earlier. The calculator lowers the limit when “preterm” is checked, but the exact plan is set by a doctor.

Newborn bilirubin: norm by age

Enter the baby’s age in hours (optionally a measured bilirubin level) — the calculator shows the typical upper limit of physiological jaundice for that age. This is a reference guide: treatment thresholds and any decision are made only by a doctor. Jaundice in the first day and any exceedance is a reason to see a pediatrician or neonatologist urgently.

Check bilirubin by age

Enter the baby’s age in hours — we’ll show the typical threshold.

Typical limit by age (term infants)

Guides to the physiological course of jaundice, NOT phototherapy thresholds. In preterm infants limits are lower. 1 mg/dL ≈ 17.1 µmol/L.

Age	Upper limit, µmol/L
under 24 hours	up to 137 (day-1 jaundice — see a doctor)
24–48 hours	up to 205
3–5 days (peak)	up to 256
5–7 days	up to 205
over 7 days	declining, to ~171

Physiological vs pathological jaundice

Most newborns develop physiological jaundice on days 2–3: the liver is still immature and can’t clear bilirubin fast enough. Levels rise toward days 3–5, then fall and usually resolve by 1–2 weeks without treatment.

Red flags: jaundice in the first 24 hours, very rapid rise, jaundice in a preterm baby, jaundice lasting beyond 2–3 weeks, plus lethargy, refusing the breast, an unusual cry. These need urgent medical review.

Why it’s only a guide

The limits in the table describe the typical physiological course but are NOT treatment thresholds. Actual phototherapy and exchange-transfusion thresholds depend on age in hours, gestational age, weight and risk factors, and are calculated by a doctor using dedicated nomograms (e.g. AAP).

So the calculator doesn’t say “treat or not”. It only helps you see whether a level is within the typical range and, in any doubtful case, points you to a doctor.

Frequently asked questions

It depends on age in hours. In term infants the typical upper limit of physiological jaundice rises to ~256 µmol/L by days 3–5, then declines. It’s a guide, not a treatment threshold — that’s set by a doctor.
Concerning signs: jaundice in the first 24 hours, rapid rise, jaundice in a preterm baby, lasting beyond 2–3 weeks, lethargy and poor feeding. These need urgent medical review.
No. Phototherapy thresholds are calculated only by a doctor using nomograms accounting for age in hours, gestational age, weight and risk factors. The calculator is a reference guide.
A preterm liver is even less mature and the risk of complications is higher, so bilirubin limits are lower and decisions are made earlier. The calculator lowers the limit when “preterm” is checked, but the exact plan is set by a doctor.

Have your baby’s test in hand?

Upload the report — the AI explains the values in plain language for the baby’s age and flags what to watch. It doesn’t replace a doctor’s exam.

Analyze baby’s test

This calculator is for information only and is not a treatment threshold. With newborn jaundice, especially in the first day, seek a doctor immediately.