Pregnancy Due Date Calculator
Enter your last menstrual period date to find your estimated due date, trimester, and weeks pregnant.
First Day of Last Menstrual Period (LMP)
Estimated Due Date
8 October 2026
Weeks Pregnant
12 weeks and 5 days
Trimester
1st Trimester (Weeks 1–13)
Days Remaining
191 days
Extended
Pregnancy Timeline
Trimester visual, key milestone dates, and week-by-week development summary
Visual pregnancy timeline — you are at week 12
1st Trimester ends
2 April 2026
2nd Trimester ends
9 July 2026
Due Date
8 October 2026
Professional
Full Pregnancy Planner
40-week calendar, appointment schedule, weight gain tracker, kick count log template
Month-by-month pregnancy calendar
Month 1Weeks 1–4
from 1 January 2026Month 2Weeks 5–8
from 29 January 2026Month 3Weeks 9–12
from 26 February 2026You are here
Month 4Weeks 13–16
from 26 March 2026Month 5Weeks 17–20
from 23 April 2026Month 6Weeks 21–24
from 21 May 2026Month 7Weeks 25–28
from 18 June 2026Month 8Weeks 29–32
from 16 July 2026Month 9Weeks 33–36
from 13 August 2026How to Use This Calculator
Select the day, month, and year of the first day of your last menstrual period (LMP). The calculator adds 280 days (40 weeks) to estimate your due date using Naegele's Rule — the standard method used by obstetricians worldwide including in Nigerian hospitals.
The Formula
Naegele's Rule:
Due Date = LMP + 280 days (40 weeks)
Pregnancy Duration = 280 days from LMP
1st Trimester: Weeks 1–13
2nd Trimester: Weeks 14–27
3rd Trimester: Weeks 28–40
Weeks Pregnant = (Today − LMP) ÷ 7
Example
LMP: 1 January 2025
Due Date8 October 2025
At 12 weeks checkMarch 26, 2025
At 20 weeks scanMay 21, 2025
FAQ
The LMP method is accurate within ±2 weeks for most women with regular 28-day cycles. A dating ultrasound scan done between 8–12 weeks is more accurate because it measures actual foetal size. Most Nigerian hospitals use LMP as the initial estimate then confirm with an early scan. Only about 5% of babies arrive exactly on the due date — most arrive within 2 weeks either side.
Naegele's Rule assumes a 28-day cycle with ovulation on day 14. If your cycle is longer (e.g. 35 days), your due date may be about a week later. If shorter (e.g. 21 days), a week earlier. Your healthcare provider will adjust the estimate based on your cycle length and ultrasound measurements.
The Nigerian Federal Ministry of Health recommends at least 8 antenatal visits: first visit at 8–12 weeks for booking and dating scan; 16 weeks, 20 weeks (anomaly scan), 24 weeks, 28 weeks (glucose test, anti-D if needed), 32 weeks, 36 weeks, and 38–40 weeks. Private hospitals in Lagos and Abuja often schedule more frequent visits. Early registration is strongly encouraged.