How to take a child's temperature and how to log it
The same thermometer in three places gives three different numbers. Pick the method that fits the age, stick with it and log the result together with the method — then the trend means something.
Last updated: 24 September 2026
Which method at which age
| Method | Age | Accuracy | Typical normal |
|---|---|---|---|
| Rectal | 0–3 years (most accurate in babies) | very high | 36.6–38.0 °C |
| Ear | from 6 months | high with good technique | 35.8–38.0 °C |
| Forehead (no-touch) | any | moderate; for screening | 35.8–37.8 °C |
| Armpit | any | low; reads 0.3–0.6 °C low | 35.5–37.5 °C |
| Oral | from 4–5 years | high | 35.8–37.8 °C |
Technique
- Ear: pull the ear gently back (down in babies), aim along the canal, measure twice and take the higher.
- Forehead: dry forehead, no hat for 10 minutes, indoors.
- Armpit: dry skin, tip in the middle of the armpit, arm pressed down, full time from the instructions.
- Rectal: lubricated tip, 1–2 cm, child on the back with knees up. A separate thermometer for this only.
How often
For a common infection 2–3 times a day and whenever the child looks worse. A reading before a medicine and about an hour after tells you whether it worked. Do not wake a sleeping child to measure.
How to log it so the doctor can use it
- time and reading with the method (38.4 °C ear),
- every dose: which product, how many ml, when,
- symptoms besides fever: cough, vomiting, rash, how much they drank.
Such a list shows whether fever drops after medicine and comes back, or keeps rising despite it. The second is a reason to see a doctor.
These numbers are conversions from leaflets and guidelines. Before giving a medicine, confirm them at the source:
- NHS: paracetamol for children · NHS: ibuprofen for children
- NICE NG143 — fever in under 5s · AAP HealthyChildren.org
- Polish medicines register (URPL) — official leaflets of the products listed here
- Your own country's medicines regulator and the leaflet in the box always take precedence.
Don't want to calculate and write this down every time?
Oh Fever does it from your child's profile and the product you use: it converts the leaflet dose to weight, counts down to the next dose and watches the daily limit — on iPhone and Apple Watch. Free for one child.
Read next
AAP — How to take a child's temperature
NICE NG143 — Fever in under 5s
This content is for information only and does not replace your doctor or the medicine leaflet. Doses on this page are the mg/kg ranges from manufacturers' leaflets converted to body weight. Check the strength on the package before giving any medicine. For high fever, any fever in an infant under 3 months, or worrying symptoms, contact a doctor.