HealthCalc Hub

Due date for a last period in October

Enter your last period start date to get a due date. This page is set up for October. The table below covers each day from day 1 to day 31.

Pick a date to see your due date.

This calculator gives general information only. It is not medical advice. Talk to a doctor or other qualified health professional about your own health.

How it works

Due date equals the first day of the last period plus 280 days. A table of every October day is below. On this page day 15 maps to 22 July.

Worked example

Use 15 October as the first day of the last period. Add 280 days for a due date of 22 July. The range for the month is 8 July to 7 August. This example uses a 365-day year.

Estimated due date for each day of October, counting 280 days from the first day of the last period. The table uses a 365-day year.

First day of last periodDue date
1 October8 July
2 October9 July
3 October10 July
4 October11 July
5 October12 July
6 October13 July
7 October14 July
8 October15 July
9 October16 July
10 October17 July
11 October18 July
12 October19 July
13 October20 July
14 October21 July
15 October22 July
16 October23 July
17 October24 July
18 October25 July
19 October26 July
20 October27 July
21 October28 July
22 October29 July
23 October30 July
24 October31 July
25 October1 August
26 October2 August
27 October3 August
28 October4 August
29 October5 August
30 October6 August
31 October7 August

Common questions

How reliable is a due date worked out by month?

It is an estimate, and births spread across the weeks around it. A last period on day 15 of October gives 22 July, with arrivals spread across the weeks around that date.

Which month will my baby be born?

The due date month is a guide, and many births come earlier or later. A last period in October points to July and August.

What if I only know the month?

Use the middle of the month. The due date then falls in the middle of the window. Day 15 of October maps to 22 July.

How many weeks is the gap?

Divide the days by 7 to get weeks. From day 1 of October to 8 July is 280 days, which is 40 weeks.

What if my cycle is not regular?

When cycles are irregular, an ultrasound can date a pregnancy more reliably than a calendar. A date of 15 October would then give 22 July only as a first guess.