What is a normal bilirubin level in a newborn?

Normal bilirubin levels depend on the baby’s age in hours. In the first 24 hours, any visible jaundice is considered abnormal. Between 24 and 72 hours, total bilirubin is often below 12 mg/dL (205 µmol/L) in healthy term babies, and after 72 hours usually below 15 mg/dL (257 µmol/L). Exact treatment thresholds depend on age, gestational age, and risk factors, which is why tools like nomograms and this calculator use age in hours.

When is bilirubin too high for a newborn?

Bilirubin is considered too high when it approaches or exceeds treatment thresholds for the baby’s age and risk profile. For many term, low-risk babies older than 72 hours, levels above about 18–20 mg/dL (308–342 µmol/L) may require phototherapy, and higher levels may require more urgent treatment. However, premature or high-risk babies need treatment at lower levels. Always follow your pediatrician’s advice and local guidelines.

What is the difference between total and direct bilirubin?

Total bilirubin is the sum of unconjugated (indirect) and conjugated (direct) bilirubin. In most healthy newborns with physiologic jaundice, the unconjugated fraction is elevated. Direct (conjugated) bilirubin is normally very low. If direct bilirubin is more than 20% of the total or above about 1–2 mg/dL (17–34 µmol/L), it may suggest cholestasis or liver disease and needs urgent evaluation.

Can I use this calculator to decide treatment for my baby?

No. This calculator is for education and general risk stratification only. It does not replace professional medical judgment or official guidelines. Treatment decisions for neonatal jaundice must always be made by a qualified clinician who knows your baby’s full medical history, exam findings, and local protocols.

How do I convert bilirubin from µmol/L to mg/dL?

To convert bilirubin from µmol/L to mg/dL, divide by 17.1. To convert from mg/dL to µmol/L, multiply by 17.1. For example, 10 mg/dL is about 171 µmol/L, and 200 µmol/L is about 11.7 mg/dL.

Bilirubin Calculator for Newborns

Interpret total and direct bilirubin levels in newborns using age in hours and risk factors. Get a clear, parent-friendly explanation of what the numbers may mean.

This tool is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.

Newborn Bilirubin Calculator

Baby's age since birth

hours

Enter age in hours (e.g. 1 day 12 hours = 36 hours). Calculator supports up to 14 days (336 hours).

Total serum bilirubin

Use the value from the lab report. You can switch between mg/dL and µmol/L.

Direct (conjugated) bilirubin (optional)

If available, enter direct bilirubin to screen for possible cholestasis (conjugated hyperbilirubinemia).

Gestational age at birth

Risk factors for severe hyperbilirubinemia

Select any that apply. This will shift the interpretation toward higher risk.

Hemolysis / positive Coombs / ABO or Rh incompatibility Known or suspected G6PD deficiency Clinical sepsis / serious illness Perinatal asphyxia / significant acidosis Low albumin (< 3 g/dL) or poor feeding / dehydration Sibling treated for jaundice

What is bilirubin?

Bilirubin is a yellow pigment produced when red blood cells are broken down. The liver processes (conjugates) bilirubin so that it can be excreted in bile and stool. In newborns, this system is still maturing, so bilirubin can build up in the blood and cause jaundice (yellowing of the skin and eyes).

A small rise in bilirubin is very common in the first days of life and is usually harmless (“physiologic jaundice”). However, very high levels can be dangerous for the brain and require prompt treatment.

How this bilirubin calculator works

This calculator helps you interpret a newborn’s bilirubin level by combining:

Age in hours since birth
Total serum bilirubin (TSB), in mg/dL or µmol/L
Optional direct (conjugated) bilirubin
Gestational age (term vs preterm)
Major clinical risk factors (hemolysis, sepsis, G6PD deficiency, etc.)

It then classifies the result into a simplified risk band (low, intermediate, high) and gives parent-friendly guidance on when to seek medical review. It is not a replacement for official nomograms or professional judgment.

1. Unit conversion

Laboratories report bilirubin either in mg/dL (common in the US) or µmol/L (common in Europe and many other regions). The calculator automatically converts between these units using:

From mg/dL to µmol/L:

\(\text{bilirubin}~[\mu\text{mol/L}] = \text{bilirubin}~[\text{mg/dL}] \times 17.1\)

From µmol/L to mg/dL:

\(\text{bilirubin}~[\text{mg/dL}] = \dfrac{\text{bilirubin}~[\mu\text{mol/L}]}{17.1}\)

2. Age bands and approximate thresholds

The risk of bilirubin toxicity depends strongly on the baby’s age in hours. The calculator uses broad age bands and approximate thresholds inspired by commonly used guidelines (e.g. AAP nomograms), simplified for educational use:

< 24 hours: any visible jaundice or TSB > 5 mg/dL (85 µmol/L) is concerning and needs urgent evaluation.
24–48 hours: TSB < 10 mg/dL (171 µmol/L) is usually low risk in term, low-risk babies.
48–72 hours: TSB < 12 mg/dL (205 µmol/L) is often low risk in term, low-risk babies.
> 72 hours: TSB < 15 mg/dL (257 µmol/L) is often low risk in term, low-risk babies.

Higher values, prematurity, or additional risk factors shift the interpretation toward intermediate or high risk and lower the suggested thresholds for review or treatment.

3. Direct vs indirect bilirubin

Total bilirubin is made of:

Unconjugated (indirect) bilirubin – not yet processed by the liver; usually elevated in physiologic jaundice.
Conjugated (direct) bilirubin – processed by the liver; normally very low in newborns.

The calculator flags possible cholestasis if:

Direct bilirubin > 1 mg/dL (17 µmol/L) when total < 5 mg/dL, or
Direct bilirubin > 20% of the total bilirubin.

These patterns may indicate liver or bile duct disease and require prompt specialist evaluation.

Typical bilirubin ranges in newborns

Exact “normal” ranges vary by lab and guideline, but the following table gives a rough idea for healthy term infants without risk factors:

Age	Typical total bilirubin	Comments
< 24 hours	< 5 mg/dL (< 85 µmol/L)	Any jaundice in first 24 h is abnormal – urgent review.
24–48 hours	Often < 10 mg/dL (< 171 µmol/L)	Higher values may still be physiologic but need closer follow-up.
48–72 hours	Often < 12 mg/dL (< 205 µmol/L)	Peak bilirubin usually occurs around day 3–5.
> 72 hours	Often < 15 mg/dL (< 257 µmol/L)	Persistent or rising jaundice after 2 weeks needs evaluation.

When to seek urgent medical help

Contact your pediatrician or emergency services immediately if:

Your baby is less than 24 hours old and looks jaundiced.
Bilirubin is very high or rising quickly (for example > 20 mg/dL / 342 µmol/L in a term baby).
The baby is lethargic, difficult to wake, feeding poorly, floppy, or has a high-pitched cry.
You notice dark urine, pale/white stools, or yellowing that persists beyond 2 weeks.

These signs can indicate severe hyperbilirubinemia or underlying liver disease and require urgent assessment.

Limitations and disclaimer

This bilirubin calculator:

Uses simplified thresholds and cannot replace official nomograms or local protocols.
Does not account for all clinical factors (weight loss, feeding pattern, ethnic background, etc.).
Is intended for education and general risk awareness only.

Always discuss your baby’s bilirubin results and any concerns with a qualified healthcare professional.