Due Date Calculator
Add 280 days to the first day of your last period. Enter the details below and read the note with your result.
How to use this calculator
Use the labelled boxes and keep every measurement in the unit shown. Press the coral calculate button once your entries look right. The result appears below the button, so you can adjust an entry and calculate again.
A quick example
Start with an ordinary number you already know, rather than a guess. Check dates carefully and make sure centimetres have not gone into a feet box. The answer is best treated as a starting point for a conversation, not a target you must chase.
Common input mistakes
The most common errors are mixed units, a date entered in the wrong year and decimal points missed on a phone keyboard. Recheck the labels before relying on the estimate. Body and pregnancy numbers naturally vary between people.
Frequently asked questions
Is this result exact?
No. It is a rough estimate based only on the information you enter.
Does HealthOnDesk save my entries?
No health account or database is used. The calculation runs in your browser.
Can I use this instead of seeing a doctor?
No. Use it to understand a number, then speak with a qualified clinician when health decisions are involved.
What if my doctor's number is different?
Follow your clinician. They have medical history, examination details and tests that this simple tool does not have.