Pregnancy Due Date Calculator (Naegele) — Fórmula
## Naegele's Rule
The estimated due date is 280 days (40 weeks) from the first day of the last menstrual period (LMP).
**Due Date = LMP + 280 days**
### Trimester Breakdown
| Trimester | Weeks |
|---|---|
| First | 1-12 |
| Second | 13-27 |
| Third | 28-40 |
Only about 5% of babies are born on their exact due date. Most arrive within 2 weeks of the estimate.
The estimated due date is 280 days (40 weeks) from the first day of the last menstrual period (LMP).
**Due Date = LMP + 280 days**
### Trimester Breakdown
| Trimester | Weeks |
|---|---|
| First | 1-12 |
| Second | 13-27 |
| Third | 28-40 |
Only about 5% of babies are born on their exact due date. Most arrive within 2 weeks of the estimate.
Ejemplo Resuelto
A woman whose last period started 84 days ago.
- Gestational week = floor(84 / 7) = 12 weeks
- Extra days = 84 - 12 x 7 = 0
- Days remaining = 280 - 84 = 196 days
- Weeks remaining = 196 / 7 = 28.0 weeks