Free baby sleep tools
🤰 Due date calculator
Enter the first day of your last period. We will estimate your due date and how many weeks pregnant you are today.
Try it now
Runs in your browser. Nothing you type is saved or sent anywhere.
How it is worked out
The standard method (Naegele’s rule) adds 280 days to the first day of your last period, adjusted for cycles longer or shorter than 28 days.
OBubba from bump to baby
OBubba follows you week by week through pregnancy for free, then becomes your baby tracker the day your baby arrives, with everything in one place.
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
How accurate is a due date calculator?
It is an estimate. The dating scan at around 11 to 14 weeks is usually used to confirm or adjust it.
When does the second trimester start?
From week 14. The third trimester starts at week 28.
What if I do not know the date of my last period?
Your midwife will date your pregnancy from your first scan.
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).