HealthCalc Hub

Due date for a last period in August

If your last period is in August, your due date falls in May and June. Use the form for the exact day, or look it up in the table.

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

Add 280 days to the first day of the last period to get the due date. The table does this for each day of August. The August table has 31 rows, one per day.

Worked example

Take 15 August as the first day of the last period. 280 days later is 22 May. The first day of August lands on 8 May and the last lands on 7 June. The year in this example has 365 days.

Estimated due date for each day of August, 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 August8 May
2 August9 May
3 August10 May
4 August11 May
5 August12 May
6 August13 May
7 August14 May
8 August15 May
9 August16 May
10 August17 May
11 August18 May
12 August19 May
13 August20 May
14 August21 May
15 August22 May
16 August23 May
17 August24 May
18 August25 May
19 August26 May
20 August27 May
21 August28 May
22 August29 May
23 August30 May
24 August31 May
25 August1 June
26 August2 June
27 August3 June
28 August4 June
29 August5 June
30 August6 June
31 August7 June

Common questions

How many weeks is the gap?

Divide the days by 7 to get weeks. From day 1 of August to 8 May 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 August would then give 22 May only as a first guess.

Does the year change the due date?

Only if the span includes 29 February, which moves the date one day earlier. If the span from 15 August includes a 29 February, 22 May reads one day earlier, as 21 May.

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 August gives 22 May, 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 August points to May and June.