Comprehensive Calculator Guide
The fundal height calculator gives the expected measurement for your week of pregnancy and compares yours if you enter it. From about week 24 the height in centimetres matches the week, give or take 2 cm. At week 28 the usual range is 26–30 cm, so 27 cm is fine, while 28 cm at week 32 is 4 cm under.
What it measures and what a gap means
It’s the distance from the pubic bone to the top of the womb, measured with a tape at check-ups. From about week 24 to 36 the centimetres track the weeks; after 36 it may hold or dip as the baby drops.
A gap of more than 2 cm can come from the baby’s position, fluid volume, twins, the mother’s build, a full bladder or measuring technique. Doctors usually check with an ultrasound. This is for information, not a substitute for antenatal care.
How to Use
- Enter the week of pregnancy, from 20 to 42.
- Add your measured height in cm if you have it (optional).
- Press “Calculate” to see the expected range and where yours sits.
Formula Used
Fundal height (cm) ≈ week of pregnancy ± 2, roughly weeks 24–36
Practical Examples
- Example 1
- Week 28, measured 27 cm: expected 28, usual 26–30, gap −1 cm.
- Example 2
- Week 32, measured 28 cm: expected 32, usual 30–34, gap −4 cm.
Important Tips
- Note your measurement at each visit; steady growth of about 1 cm a week matters most.
Common Mistakes to Avoid
- Applying the rule before week 24.
Frequently Asked Questions
- What is normal fundal height at 30 weeks?
- About 30 cm, usually 28–32 cm.
- What if I measure small for my dates?
- It may be position, fluid or technique; your doctor will usually order an ultrasound.
- What if I measure large?
- A bigger baby, extra fluid, twins or a dating error are possible causes.