Fundal Height Reference
The cm-equals-weeks rule with its honest ±3 window — what the tape measurement at each visit means.
It's a screening tape-measure, not a verdict — baby's position, your build, fluid volume and a full bladder all move it, and serial *trend* matters more than one number. 'Measuring big' panic and 'measuring small' panic are the two most common needless pregnancy scares; the follow-up scan exists precisely because the tape is rough.
Formula
For general information only. Pregnancy and infant care decisions must be guided by your treating clinician or midwife — always defer to their assessment.
The cm-equals-weeks rule with its honest ±3 window — what the tape measurement at each visit means. The Fundal Height Reference is a free, private fundal height tool — every result computes instantly in your browser with no sign-up and no data upload.
About Fundal Height Reference
It's a screening tape-measure, not a verdict — baby's position, your build, fluid volume and a full bladder all move it, and serial *trend* matters more than one number. It applies after 20 weeks: fundal height (cm) ≈ gestational weeks ± 3. Use the Fundal Height Reference to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Fundal Height Reference
- 1Enter your details in the Fundal Height Reference input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Fundal Height Reference?
- ✓Instant fundal height result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Papageorghiou AT et al., BMJ 2016 — INTERGROWTH-21st fundal height standards)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Fundal Height Reference work?+
It's a screening tape-measure, not a verdict — baby's position, your build, fluid volume and a full bladder all move it, and serial *trend* matters more than one number. The calculation uses the formula: after 20 weeks: fundal height (cm) ≈ gestational weeks ± 3. Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Fundal Height Reference accurate, and what is it based on?+
The method is traceable to authoritative sources: Papageorghiou AT et al., BMJ 2016 — INTERGROWTH-21st fundal height standards. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Fundal Height Reference free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is informational only. Always defer to your treating clinician or midwife for pregnancy and infant care decisions.
What can I use the Fundal Height Reference for?+
It's commonly used for fundal height, fundal height by week, measuring big small pregnancy. The cm-equals-weeks rule with its honest ±3 window — what the tape measurement at each visit means.
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