What is Vacation Planner?

Vacation Planner is a web tool that helps you plan your vacation dates, taking into account the probability of menstruation for women with irregular cycles.
It uses a Monte Carlo simulation to estimate the probability of having a period on each day of your vacation, based on your cycle parameters and the date of your last period.

How does it work?

  1. You enter the date of your last period, the minimum and maximum cycle length (in days), and the period length (in days).
  2. You specify one or more vacation periods (start and end dates).
  3. The algorithm simulates thousands of possible cycles and calculates the probability of having a period for each day of your vacation.
  4. The result is shown as a color-coded calendar, where each cell shows the probability for that day (from green to red).

Who is this for?

  • Women with irregular menstrual cycles who want to plan vacations or important events.
  • Partners and families who want to avoid planning trips during high-probability days.
  • Anyone who wants a visual, data-driven approach to menstrual cycle prediction.

How to use

  1. Fill in your last period date, cycle range, and period length at the top of the page.
  2. Add one or more vacation periods (you can add multiple by clicking "Add vacation period").
  3. Click Calculate probabilities.
  4. Scroll down to see the calendar with color-coded probabilities for each day.

How does the algorithm work?

The algorithm uses a Monte Carlo simulation:
For each simulation, it randomly picks a cycle length from your range, and simulates periods starting from your last period date. For each vacation day, it counts how often that day falls within a period. The final probability is the ratio of simulations where the day is "in period" to the total number of simulations.

Is my data safe?

No data is stored or shared.