What is the normal temperature for a baby?

A baby's normal temperature ranges from 36.5°C to 37.5°C (97.7°F to 99.5°F) when measured in the armpit. Values between 35.5°C and 36.4°C are also normal but may indicate the baby is cold.

Is 37°C (98.6°F) a fever in a baby?

No. 37°C is within the normal temperature range for babies (36.5°C to 37.5°C axillary). Fever is only considered from 37.8°C (100°F) in the armpit.

Is 37.5°C (99.5°F) a fever in a baby?

37.5°C is the upper limit of the normal range (low-grade temperature). It is not fever, but you should observe the child and re-measure after 30 minutes. If it rises above 37.8°C, it is considered fever.

How do I measure a baby's temperature correctly?

For babies, the most practical method is axillary (under the arm) with a digital thermometer. Hold the baby's arm against their body for 3-5 minutes. For newborns under 3 months, the rectal method is the most accurate.

What is the best thermometer for a baby?

A digital thermometer is the most recommended by pediatric societies as it is safe, accurate, and easy to use. Avoid mercury thermometers (banned in many countries) and use forehead thermometers only for quick screening, not clinical decisions.

Normal Baby Temperature by Age: Complete Chart and Measuring Guide

“My baby is at 37°C — is that a fever?” This is one of the questions I hear most often from worried parents. The truth is that your baby's temperature varies throughout the day and depends on several factors. In this guide, I will show you exactly what the normal range is for each age and how to measure correctly. Remember to bring these questions to your routine pediatric checkups.

Normal Baby Temperature Chart by Age

A baby's body temperature is slightly different from an adult's and can vary with age. Here is the reference chart:

Age	Normal Temp (axillary)	Fever From	Note
Newborn (0-28 days)	36.5-37.5°C (97.7-99.5°F)	37.8°C (100°F)	Any fever = see pediatrician immediately
1-3 months	36.5-37.5°C (97.7-99.5°F)	37.8°C (100°F)	Any fever = see pediatrician immediately
3-6 months	36.5-37.5°C (97.7-99.5°F)	37.8°C (100°F)	Watch for warning signs
6-12 months	36.5-37.5°C (97.7-99.5°F)	37.8°C (100°F)	Can monitor at home if otherwise well
1-3 years	36.5-37.5°C (97.7-99.5°F)	37.8°C (100°F)	Observe overall condition
Over 3 years	36.0-37.5°C (96.8-99.5°F)	37.8°C (100°F)	Same reference as adults

Important: The normal temperature range is the same at all ages. What changes is the urgency of the response to fever: the younger the baby, the more urgent it is to seek medical care. In newborns and babies under 3 months, any fever requires immediate medical evaluation.

What Makes a Baby's Temperature Fluctuate?

A baby's temperature fluctuates throughout the day. This is completely normal and does not indicate illness:

Temperature rises naturally when:

▲After feeding or eating
▲After prolonged crying
▲After a warm bath
▲With excess clothing or blankets
▲In the late afternoon (circadian variation)
▲During teething (slight increase)

Temperature drops naturally when:

▼During the early morning hours
▼With light clothing or no blanket
▼In cold rooms or with air conditioning
▼After a bath (if not too hot)
▼During deep sleep

Important Tip

If your baby's temperature is between 37.0°C and 37.5°C (98.6°F and 99.5°F) and they just finished feeding, crying, or were bundled up, wait 15-20 minutes in light clothing and measure again. It often returns to normal.

Questions about your baby's temperature?

Dr. Paula can guide you on when to worry and what to do.

Talk to the Pediatrician

How to Measure Your Baby's Temperature: Step by Step

Axillary Method (Most Common)

1Dry the armpit with a towel (sweat affects the reading)
2Place the tip of the digital thermometer in the armpit
3Hold the baby's arm gently against their body
4Wait for the beep (usually 1-3 minutes)
5Read the display. This is the axillary temperature

Comparison of Measurement Methods

Method	Accuracy	Recommended Age	Difference vs Axillary
Rectal	Most accurate	0-3 months (gold standard)	+0.5°C / +1°F above axillary
Axillary	High	All ages	Reference
Ear (tympanic)	Moderate	Over 6 months	+0.3°C / +0.5°F above axillary
Forehead (infrared)	Low	Quick screening only	Variable

Which Thermometer Should You Buy?

A digital axillary thermometer is sufficient for most families. In Brazil, these cost between R$15-30 (about US$3-6) and are available at any pharmacy.

Avoid: mercury thermometers (banned in many countries including Brazil since 2019) and forehead thermometers for clinical decisions (good only for quick screening).

Hypothermia in Babies: When the Temperature Is Too Low

Parents usually worry only about fever, but a temperature that is too low also requires attention, especially in newborns:

Hypothermia Classification in Babies

36.0-36.4°C (96.8-97.5°F): Mild hypothermia. Bundle up and warm the room. Re-measure in 30 minutes.
35.0-35.9°C (95.0-96.6°F): Moderate hypothermia. Place baby skin-to-skin on your chest. If it does not improve, seek medical care.
Below 35.0°C (95.0°F): Severe hypothermia. Seek immediate medical attention.

When to See the Pediatrician

If the temperature exceeds the normal range, check our complete guide to baby fever to know exactly when it is urgent and when you can monitor at home.

Seek Immediate Medical Care If:

Baby 0-3 months with any fever (37.8°C / 100°F or above)
Temperature below 35°C (95°F) that does not improve with warming
Fever above 39.5°C (103.1°F) that does not respond to fever medicine
Baby is lethargic, unresponsive, or has difficulty breathing

For Expat Families in Sao Paulo

In Brazil, axillary temperature measurement is the standard method — this differs from some countries where rectal or ear thermometers are preferred. Brazilian pediatricians use Celsius exclusively, so it is helpful to familiarize yourself with the scale. Dr. Paula provides all guidance in English and can help you understand how Brazilian pediatric practices compare with those in your home country. Learn about finding an English-speaking pediatrician and consultation costs.

Scientific References

• Brazilian Society of Pediatrics (SBP). Scientific Document #206: Approach to Acute Fever in Pediatrics. 2025.
• Brazilian Ministry of Health. Child Health Booklet. 2025 Update.
• Brazilian Society of Pediatrics. Guidelines: Thermoregulation in the Newborn.

Originally published February 1, 2026