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Fitness and Health Calculators

Period Calculator

Your cycle
Result

April 2026

S
M
T
W
T
F
S
29
30
31
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
2
3
4
5
6
7
8
9

May 2026

S
M
T
W
T
F
S
26
27
28
29
30
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
1
2
3
4
5
6

June 2026

S
M
T
W
T
F
S
31
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
1
2
3
4
5
6
7
8
9
10
11
Period daysMost probable ovulation days

Important dates for the next 6 cycles:

PeriodMost probable ovulation days
Apr 10, 2026 – Apr 14, 2026Apr 22, 2026 – Apr 26, 2026
May 8, 2026 – May 12, 2026May 20, 2026 – May 24, 2026
Jun 5, 2026 – Jun 9, 2026Jun 17, 2026 – Jun 21, 2026
Jul 3, 2026 – Jul 7, 2026Jul 15, 2026 – Jul 19, 2026
Jul 31, 2026 – Aug 4, 2026Aug 12, 2026 – Aug 16, 2026
Aug 28, 2026 – Sep 1, 2026Sep 9, 2026 – Sep 13, 2026

Educational estimate only—not for diagnosis. Irregular cycles vary; see a clinician if concerned.

Ovulation band = cycle day 1 + (cycle − 14), ±2 days. Period length sets bleeding days only.

Period Calculator: Calendar & 6-Cycle Outlook

How to use

  • Set the first day of your last menstrual period.
  • Choose how many days bleeding usually lasts (1–10).
  • Set average cycle length; use the arrows to move the calendar by three months.

What we calculate

Each cycle starts on period day 1. Bleeding spans the number of days you chose. Estimated ovulation peak is at LMP + (cycle length − 14); the “most probable ovulation days” band is peak ±2 days, matching common period-calculator layouts.

Guide

What this tool does

The period calculator estimates future period days and the most probable ovulation days in a calendar view, similar to common educational period calendars. You enter the first day of your last period, typical bleeding length, and average cycle length.

Three months are shown at a time with navigation; a table lists the next six cycles with period ranges and ovulation windows.

Notes

Regular cycles

Estimates assume fairly stable cycle length; large month-to-month variation reduces accuracy.

Limitations

  • Not birth control and not a substitute for medical advice.
  • Does not model pregnancy, breastfeeding, or hormonal treatment.

FAQ

Why three months?

It matches the usual period-calculator layout so you can scan a quarter at a time.