Free baby sleep tools
🐣 Corrected age calculator
If your baby arrived early, their corrected age (age from the due date) gives a fairer picture for sleep, feeding and milestones. Enter both dates to work it out.
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Why corrected age matters
A baby born eight weeks early who is four months old has the developing brain of a two month old. Comparing them to four month olds can make normal progress look slow and push sleep expectations too far.
How OBubba uses it
Add your due date in OBubba and the app plans wake windows, naps and milestone expectations from corrected age automatically.
Let OBubba do this for you
This chart is the average baby. OBubba learns yours.
OBubba learns your baby’s own wake windows from what you log, predicts the next nap and bedtime, and spots over 30 common sleep disruptions with a gentle plan for each. Free to download.
Questions parents ask
Frequently asked questions
Until what age do you use corrected age?
Usually until about two years old, when most premature babies have caught up.
Should I use corrected age for wake windows?
Yes. Sleep develops with brain maturity, so corrected age is the better guide for wake windows and nap counts.
Should I use corrected age for weaning?
Many specialists suggest starting solids around 6 months actual age while also looking for readiness signs. Ask your neonatal team or health visitor for advice for your baby.
Related guides
More free tools
Baby sleep schedule makerA full sample day of naps and bedtime from your baby’s age and wake-up time.
Wake window calculatorHow long your baby can comfortably stay awake between sleeps.
Why is my baby waking at night?Answer a few questions to see the most likely reasons for night wakes.
Baby bedtime calculatorThe right bedtime from when the last nap ended.
How much sleep does my baby need?How much sleep your baby needs in 24 hours, at night and in the day.
Sleep regression checkerWhich common sleep shake-ups line up with your baby’s age, and what helps.Sources
OBubba tools give general, age-based information. They are not medical advice and do not diagnose anything. Every baby is different. If you are worried about your baby, speak to your health visitor, midwife, GP or call NHS 111 (or your local equivalent).