How the sleep calculator works
Enter your baby’s date of birth and their usual morning wake-up time. The calculator works out your baby’s age and shows the typical wake window, number of naps and total sleep for that age. From about three months, it also builds a sample day: the first wake window of the day is usually the shortest and the one before bed the longest, so the naps and bedtime are spaced that way.
Wake windows and naps by age
| Age | Wake window | Naps | Total sleep (24 h) |
|---|---|---|---|
| 0–4 weeks | 35–60 min | On demand | 14–17 h |
| 1–3 months | 60–90 min | 4–5 | 14–17 h |
| 3–5 months | 75 min – 2 h | 3–4 | 12–16 h |
| 5–7 months | 2–3 h | 3 | 12–16 h |
| 7–9 months | 2.5–3.5 h | 2–3 | 12–16 h |
| 9–12 months | 3–4 h | 2 | 12–16 h |
| 12–18 months | 4–6 h | 1–2 | 11–14 h |
| 18 months – 3 years | 5–6 h | 1 | 11–14 h |
Total sleep ranges follow recommendations from sleep medicine experts. Wake windows are common practical guides, not rules — some babies need more or less.
Signs your baby is tired
- Early cues: yawning, staring into space, slowing down, rubbing eyes or ears.
- Later cues: fussing, crying, arching or becoming “wired” — often a sign the wake window has run long.
Offering sleep when early cues appear often makes settling easier.
Safe sleep
For every sleep, day and night, place your baby on their back in their own clear, flat, firm sleep space — a cot, crib or Moses basket — with no pillows, bumpers or loose bedding, in a smoke-free room. Sharing a room (but not a bed) for at least the first six months is recommended by many health services.
Every baby is different, and sleep often changes around growth spurts, illness, teething and developmental leaps. If you are worried about your baby’s sleep or breathing, speak to your doctor or health visitor. For babies born early, using corrected age can give a better guide.