HealthCalc Hub

Due date for a last period in May

A last period in May puts the due date between 5 February and 7 March. The table lists every day.

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

Count 280 days forward from the first day of the last period. The result is the estimated due date. In May the due dates run through February and March.

Worked example

Start at 15 May. Count 280 days ahead to reach 19 February. Across the whole month the due dates run from 5 February to 7 March. This example assumes a 365-day year.

Estimated due date for each day of May, 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 May5 February
2 May6 February
3 May7 February
4 May8 February
5 May9 February
6 May10 February
7 May11 February
8 May12 February
9 May13 February
10 May14 February
11 May15 February
12 May16 February
13 May17 February
14 May18 February
15 May19 February
16 May20 February
17 May21 February
18 May22 February
19 May23 February
20 May24 February
21 May25 February
22 May26 February
23 May27 February
24 May28 February
25 May1 March
26 May2 March
27 May3 March
28 May4 March
29 May5 March
30 May6 March
31 May7 March

Common questions

How many weeks is the gap?

Divide the days by 7 to get weeks. From day 1 of May to 5 February 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 May would then give 19 February 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. The span from 15 May does not cross February. A leap year changes nothing for 19 February.

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 May gives 19 February, 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 May points to February and March.