Veses Kavua: When a Pattern Becomes a Fixed Veses
5 min read · October 22, 2026
Most women have no fixed pattern, and keep the three vestos from each period afresh — this is an eino kavua veses. When the same pattern repeats three times, it becomes a veses kavua: a fixed veses, kept even when a period comes elsewhere.
How it is established
- Veses hachodesh kavua: three periods on the same Hebrew date in three consecutive months.
- Veses haflagah kavua: three equal intervals — which takes four periods.
- A dilug: intervals that grow by the same step each time, such as 31, 32 and 33 days.
What changes
A fixed veses is anticipated on its day every month, whether or not the last period fell there. Opinions differ on whether the onah beinonis is still kept alongside it; many calendars keep both unless the rav says otherwise.
Uprooting it
A veses kavua is uprooted by three times its day passes without a period. Whether that has happened — and whether a new pattern has replaced the old — is a question for your rav, not for a calendar.
What does not count
A veses is not established during pregnancy or nursing, and periods on either side of such a time do not combine to make three.
This guide explains the general rules and the common customs. Where poskim differ it says so — it does not rule. For your own questions, ask your rav.
Questions
- How is a veses kavua established?
- By three repetitions: the same Hebrew date in three consecutive months, or three equal intervals (four periods).
- Do I still keep the onah beinonis with a veses kavua?
- Opinions differ. Ask your rav; many keep both until told otherwise.