# Pregnancy Due Date Calculator

> Calculate your due date and current pregnancy week from your last period or known conception date. Includes trimester and key milestones.

URL: https://uttir.com/pregnancy-calculator
Categories: calculators
Privacy: Your dates never leave the browser.

## About

Two ways to estimate a due date. The default is Naegele's rule: due date = first day of last period + 280 days (40 weeks). This works if your cycles are roughly 28 days. If you know the conception date (IVF transfer, known ovulation, IUI), use that mode — it adds 266 days instead.

The calculator shows the current week and day, which trimester you're in, days until the due date, and the key milestone dates (heartbeat detectable at 7 weeks, anatomy scan at 20 weeks, viability at 24 weeks, full term at 37 weeks).

## How to use

1. **Pick the input mode** — LMP (last menstrual period) or known conception date.
2. **Pick the date** — For LMP: the first day of your most recent period. For conception: the date of ovulation, IUI, or embryo transfer.
3. **Read the result** — See the due date, current week/day, trimester, and milestone dates.

## Examples

### LMP on January 1

Standard 28-day cycle.

Output:

```
Due date: October 8
```

### Conception on February 14

Known timing.

Output:

```
Due date: November 7 (266 days later)
```

## FAQ

### How accurate is the due date?

Only about 4-5% of babies are born on their actual due date. The due date is a midpoint of a 5-week range (37-42 weeks is considered full term). Use it for planning, not as a deadline.

### What if my cycle is longer or shorter than 28 days?

Naegele's rule assumes 28-day cycles. For longer or shorter cycles, the due date is off by the same number of days. Conception-date mode is more accurate when you know the actual date of ovulation.

### When will the first ultrasound be more accurate?

The first-trimester ultrasound (8-13 weeks) measures the crown-rump length, which is the most accurate due-date method outside of IVF. Use the calculator as an estimate until your dating scan.

## Related tools

- [Age Calculator](https://uttir.com/age-calculator) — Find the exact age in years, months, and days — plus totals and the countdown to the next birthday.
- [Date Calculator](https://uttir.com/date-calculator) — Count the days between two dates, or add and subtract days from any date.
- [Date Add/Subtract Calculator](https://uttir.com/date-add-subtract) — Add or subtract days, weeks, months, or years from any date. Handles month-end and leap-year rollovers.
- [BMI Calculator](https://uttir.com/bmi-calculator) — Calculate your Body Mass Index and see where you fall on the healthy range.

---

For the full HTML page with the live tool, visit https://uttir.com/pregnancy-calculator.
This file is the markdown rendering at https://uttir.com/pregnancy-calculator.md. See https://uttir.com/llms.txt for a site-wide summary.