Pregnancy due date calculator
Naegele's rule from last menstrual period (+280 days). An estimate—confirm with your doctor.
Runs in this tab. The file stays here.
Estimated due date
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Naegele's rule: last menstrual period + 280 days. Pregnancies vary — confirm with your doctor.
This runs in your browser. Nothing is uploaded.
About Pregnancy due date calculator
Pregnancy due date from last menstrual period using Naegele's rule plus 280 days. Confirm with your doctor.
This due date calculator stays in the tab. Nothing is uploaded to ihateonlinetools.com for the calculation. That is the same offline promise as the rest of the site: your numbers, caption, or recipe never need to sit in a third-party form log.
Naegele's rule adds two hundred eighty days to the first day of the last menstrual period. The date is a standard estimate; ultrasound dating and clinical judgment often adjust it.
Say confirm with your doctor once, plainly. The tool does not track pregnancy week-by-week or store health records. Related tools on this site cover nearby jobs without forcing a signup wall.
How to use Pregnancy due date calculator
- 1Open /health/due-date-calculator/ and check the side-panel defaults.
- 2Enter your values or paste your list; the main pane updates.
- 3Copy the result if you need it elsewhere. Closing the tab clears local state unless noted.
What it won't do
- Not professional advice and not a hosted account product.
- Garbage in, garbage out: wrong inputs yield wrong outputs.
Common questions
Does due date calculator upload anything?
No. Inputs and outputs stay in the browser process. Sharing features that exist, such as countdown links, only put values you choose into the URL on your device.
What formula or method does due date calculator use?
Naegele's rule adds two hundred eighty days to the first day of the last menstrual period. The date is a standard estimate; ultrasound dating and clinical judgment often adjust it.
When should I not rely on due date calculator alone?
When a clinician, building code, platform policy, or teacher requires a signed process. This page is a calculator and explainer, not a certificate.
Is due date calculator free and offline-capable?
Yes. After the static page loads, the logic runs without calling an external compute API. Return visits may use the service worker cache for the shell.
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Why this one doesn't upload your file
There is no server to upload to. This page is a static file, and the work happens in your browser using the same graphics and WebAssembly code that renders every other site you visit. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network entirely and it keeps working. The longer explanation