Baby and pregnancy calculators, from first scan to first steps
Due dates, weeks pregnant, WHO growth percentiles, wake windows, bottle amounts and names. Every calculator runs in your browser, instantly, and nothing you type is sent anywhere.
When is the baby due?
28 days is the textbook default. Longer cycles usually mean later ovulation, so a later due date.
Pick a date to see your due date.
All calculators
Pregnancy
Dates, weeks and what happens when.
- Due date calculatorFrom your last period, conception, IVF transfer or an ultrasound.
- Pregnancy calculatorHow many weeks pregnant you are, your trimester and what is next.
- IVF due date calculatorDay 3, day 5 or day 6 transfers and egg retrieval dates.
- Conception date calculatorWork backwards from a due date to the likely conception window.
- Ovulation calculatorFertile window and ovulation day for your next three cycles.
- Pregnancy week by weekBaby size, weight and development for weeks 4 to 42.
- Pregnancy weight gain calculatorRecommended gain for your BMI, week by week, singles or twins.
- hCG doubling time calculatorDoubling time between two beta hCG results.
Growth
Percentiles on the WHO standards your paediatrician uses.
- Baby percentile calculatorWeight, length and head percentiles on WHO or CDC growth charts.
- Baby weight percentileWeight-for-age percentile, birth to 5 years.
- Baby length / height percentileLength-for-age and height-for-age percentile.
- Head circumference percentileHead-circumference-for-age percentile.
- Baby weight chart by monthAverage weight and normal range for boys and girls, 0–24 months.
- WHO growth chart tablesPercentile tables for boys and girls, month by month.
- CDC growth chart calculatorCDC percentiles to age 20, and why the chart changes at 2.
- Child height predictorEstimate adult height from parents or toddler height.
Sleep & feeding
The two questions you'll ask at 3 a.m.
- Wake windows & sleep scheduleWake windows by age and a nap schedule built from wake-up time.
- Baby sleep schedule by ageNaps, wake windows and a sample day for every age, newborn to 3.
- Baby feeding calculatorFormula and breast milk amounts per bottle and per day.
- Baby feeding chart by ageHow much and how often to feed, newborn to 12 months.
Names
From a shortlist to the one.
Sizes & milestones
Ages, sizes and what to expect.
- Baby age calculatorAge in weeks, months and days, plus upcoming milestones.
- Adjusted age calculatorCorrected age for babies born early.
- Baby milestones by monthCDC milestone checklists from 2 months to 3 years.
- Baby eye color predictorOdds of brown, green or blue eyes from both parents.
- Baby shoe size chartFoot length to US, UK and EU sizes.
- Baby clothes size chartWeight and length to the right clothing size.
Numbers that come with a source
Growth percentiles use the WHO Child Growth Standards (the same curves the CDC recommends for every child under two), computed from the official LMS tables. Due dates follow Naegele's rule with the cycle-length and IVF adjustments recommended by ACOG. Wake windows and feeding amounts are ranges drawn from the AAP's HealthyChildren.org guidance, because babies don't read charts.
Every tool explains how it gets its answer. If something looks off, the explanation on each page shows you exactly where the number came from, so you can take it to your midwife or paediatrician with confidence.