About the RRULE to Human Readable Converter

Welcome to the most comprehensive RRULE (Recurrence Rule) converter available online. This tool transforms complex RFC 5545 recurrence patterns used in iCalendar applications into simple, easy-to-understand plain English descriptions. Whether you're a developer working with calendar APIs, a system administrator managing recurring events, or simply curious about decoding those cryptic RRULE strings, this tool provides instant, accurate translations.

RRULE is the industry standard for expressing recurring events in digital calendars. It's used by Google Calendar, Microsoft Outlook, Apple Calendar, and virtually every calendar application worldwide. However, these rules can be incredibly difficult to read and understand. Our converter bridges that gap, making recurrence patterns accessible to everyone.

What sets this tool apart is its precision and depth. Not only does it convert your RRULE to plain English, but it also shows you the next five occurrences of your recurring event, breaks down individual rule components, and validates syntax in real-time. You can share your converted rules via URL, copy results instantly, and use pre-built templates for common patterns.

How It Works

The RRULE format is defined in RFC 5545 (Internet Calendaring and Scheduling Core Object Specification). It consists of property-value pairs separated by semicolons. Our converter parses each component and reconstructs a natural language description that anyone can understand.

Key RRULE Components

• FREQ – Frequency (DAILY, WEEKLY, MONTHLY, YEARLY)
• INTERVAL – How often the recurrence repeats (e.g., every 2 weeks)
• COUNT – Total number of occurrences
• UNTIL – End date for the recurrence
• BYDAY – Specific days of the week (MO, TU, WE, TH, FR, SA, SU)
• BYMONTH – Specific months (1-12)
• BYMONTHDAY – Day of the month (1-31 or -1 for last day)
• BYSETPOS – Position in a set (e.g., 1st, 2nd, last)
• WKST – Week start day (defaults to Monday)

Our parser handles complex combinations including negative positions (like "last Friday of the month"), multiple weekdays, month-specific patterns, and more. The algorithm calculates future occurrences using the parsed rules, providing you with concrete examples of when events will occur.

How to Use This Tool

1. Choose a Template – Start with one of our pre-built templates for common patterns, or jump straight to entering your own.
2. Enter Your RRULE – Paste or type your recurrence rule in the text field. You can include or omit the "RRULE:" prefix.
3. Click Convert – Press the Convert button to see your rule translated to plain English.
4. Review Results – See the human-readable description, detailed breakdown, and next five occurrences.
5. Copy or Share – Use the Copy button to copy the result to your clipboard, or Share to generate a URL with your RRULE encoded.

Example RRULEs

• FREQ=DAILY;INTERVAL=2 → "Every 2 days"
• FREQ=WEEKLY;BYDAY=MO,WE,FR;COUNT=10 → "Every week on Monday, Wednesday, and Friday, 10 times"
• FREQ=MONTHLY;BYDAY=1MO → "Every month on the first Monday"
• FREQ=YEARLY;BYMONTH=12;BYMONTHDAY=25 → "Every year on December 25"

Tips & Best Practices

• Validate Before Use – Always test your RRULE with this converter before implementing it in production systems.
• Consider Timezones – RRULEs are timezone-agnostic. Make sure to handle timezone conversions separately in your calendar application.
• Use DTSTART – In actual iCalendar files, combine RRULE with DTSTART (start date) for complete recurrence definitions.
• Limit Complexity – While RFC 5545 allows very complex rules, simpler patterns are easier to maintain and less prone to edge cases.
• Test Edge Cases – Check how your rule behaves on month boundaries, leap years, and daylight saving transitions.
• Document Your Rules – Use this tool to generate documentation for your recurrence patterns in project specs.

Frequently Asked Questions

Common Mistakes to Avoid

• Lowercase Properties – RRULE properties must be uppercase. Use FREQ=DAILY, not freq=daily.
• Missing FREQ – The FREQ property is mandatory in every RRULE. You cannot have a recurrence without specifying frequency.
• Invalid Day Codes – Days must be two-letter codes: MO, TU, WE, TH, FR, SA, SU. Full names or numbers don't work.
• Wrong Separators – Use semicolons (;) between properties and commas (,) within lists. Don't use spaces or other characters.
• BYMONTHDAY Conflicts – Using BYMONTHDAY=31 with months that don't have 31 days will skip those months. Consider if this is intentional.
• COUNT vs UNTIL – Don't use both COUNT and UNTIL in the same RRULE. Choose one end condition.
• Negative Positions – -1 means last, -2 means second-to-last. Don't confuse with absolute positions.