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How to Take Your Baby's Temperature and What's Considered Normal

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How to Take Your Baby's Temperature and What's Considered Normal

Reviewed by pediatrician and pediatric gastroenterologist Anna Talybin

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How the temperature tracker works

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The temperature tracker helps you record your baby's temperature and see whether it's within the normal range — and if your baby gets sick, track how it changes over time.

In the app, you can choose how the temperature was taken:

  • rectally
  • under the arm
  • in the ear
  • on the forehead

— and record the reading.

Once you save it, the app shows whether the reading is within the normal range, elevated, or considered a fever.

Ways to take your baby's temperature and how they differ

Temperature readings can vary depending on where on the body they're taken, so each method has its own thresholds for normal and elevated temperatures.

Rectal readings are the closest to the body's internal temperature and are generally used as a reference. Other methods usually give slightly lower readings, which is why their normal ranges are different.

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For babies under 3 months, temperature is usually taken rectally at home, and after that, under the arm.

Rectal

  • Recommended for babies under 3 months when it's important to accurately confirm or rule out a fever.
  • If your baby is under 3 months and another method shows a temperature around 100.4°F (38.0°C), it's best to double-check with a rectal reading.
🟩 Normal (up to)🟨 Elevated🟥 High
99.5°F (37.5°C)99.7–100.4°F (37.6–38.0°C)≥ 100.4°F (38.0°C)

Ear

  • Measures infrared radiation from the eardrum.
  • Ear thermometers usually come with special tips that make it easier to take a reading.
  • Babies have narrow ear canals, and an incorrect angle can often result in a reading that's too low. It shouldn't be used as the only method to confirm a fever in babies under 3 months and is more appropriate after 6 months.
🟩 Normal (up to)🟨 Elevated🟥 High
98.8°F (37.1°C)99.0–99.7°F (37.2–37.6°C)≥ 99.7°F (37.6°C)

Under the arm

  • Safe to use from birth.
  • Underarm temperature is usually about 0.9–1.1°F (0.5–0.6°C) lower than rectal temperature and may miss a borderline fever.
  • It can be used to track changes over time if your baby is older than 3 months and otherwise doing well.
🟩 Normal (up to)🟨 Elevated🟥 High
98.4°F (36.9°C)98.6–99.3°F (37.0–37.4°C)≥ 99.3°F (37.4°C)

Forehead

  • A quick, contact-free method. However, it measures skin temperature, which can be affected by the environment.
  • Cold air, a hat, sweat, or your baby's movement can affect the reading. It works well for an initial check, but if you're unsure, it's better to double-check with a more accurate method.
🟩 Normal (up to)🟨 Elevated🟥 High
98.1°F (36.7°C)98.2–99.0°F (36.8–37.2°C)≥ 99.0°F (37.2°C)

What can affect a temperature reading

  • crying
  • being bundled up
  • recent feeding
  • movement
  • room temperature
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If a reading seems unusual, taking your baby's temperature again after 20–30 minutes can often give you a clearer picture.

When to contact a doctor

  • Your baby is under 3 months and has a temperature of 100.4°F (38.0°C) or higher, or your baby is over 3 months and has a temperature of 102.2°F (39.0°C) or higher
  • The fever lasts for several days
  • Seizures
  • Difficulty breathing
  • Severe lethargy or difficulty waking up
  • A rash that doesn't fade when pressed
  • Signs of dehydration (less frequent urination, dry lips, no tears)
  • Your baby's condition is getting worse
  • Something about your baby's condition concerns you
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Temperature isn't the only thing to watch: infections can sometimes develop even with only a moderate rise in temperature. If you're concerned about how your baby is doing, contact your pediatrician.

In babies under 3 months, even a single episode of fever requires medical evaluation.

With care

Our articles are based on evidence-based medicine and reviewed by pediatricians. However, they do not replace a consultation with your doctor. Every child is unique — if you have any concerns, please consult a medical professional.