The earliest likely arrival based on your recent shortest cycle.
Intent-focused tool page
Irregular period calculator
Use this irregular period calculator to estimate the earliest and latest timing for your next period when your cycle length changes month to month.
Range-based forecast
Estimate the next period window for irregular cycles
When your cycle length changes from month to month, this page gives you an arrival range instead of pretending there is one exact date.
Last period start
Shortest cycle24 days
Longest cycle35 days
The latest likely arrival based on your recent longest cycle.
A wider fertile estimate fits a more variable cycle.
Calculated as longest cycle minus shortest cycle.
This page captures narrower intent. The value comes from framing everything as a realistic window with softer planning guidance.
Your current cycle spread is 11 days, which is why this page works with a wider timing window.
Why this page matters
A range is the right shape for a cycle that moves around.
Plan with a range
A window is easier to trust than one exact day when your body rhythm changes month to month.
Reduce false precision
The earliest and latest dates help with travel, appointments, and packing rather than pretending the month is perfectly predictable.
Grow with more logs
As your saved history grows, the range can become more personal and more useful.
FAQ
Answer the core questions around irregular timing clearly.
Why use a range instead of one exact date?
This page uses your shortest and longest recent cycles to estimate an arrival window instead of one date.
What does the cycle spread mean?
A wider spread often means a broader planning window. Logging a few more months can tighten the estimate.
Why is the fertile window shown as a range too?
The fertile estimate is also a range here because ovulation can move earlier or later across different cycles.
When should I ask for medical guidance?
Very irregular cycles, missing periods, or sharp changes in your usual rhythm deserve medical support.