How to Add Holidays to P6 Calendar?

When working on construction schedules in Primavera P6, accurately defining your calendar is just as important as defining the activities themselves. Whether you’re planning a high-rise tower or an infrastructure project, the calendar directly influences your project logic, durations, float calculations, and your completion date. In this article, we’ll walk through the concept of calendars in P6, their importance, and most importantly, how to add holidays to P6 calendar to ensure accurate planning.

What Are Calendars in P6 and Why Are They Important?

In Primavera P6, a calendar defines the working and non-working time periods for your project. This includes workdays, work hours per day, weekends, and holidays. The calendar affects how durations are calculated and how activities are scheduled over time. For example, if you define an activity as having a 10-day duration, it doesn’t mean 10 calendar days; it means 10 working days based on the assigned calendar.

Using incorrect or incomplete calendars may result in unrealistic schedules, inaccurate resource allocation, or misleading end dates. That’s why every professional planning engineer must ensure their calendars reflect the real working conditions of their project site.

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Why You Need a Calendar for Each Project

Not all projects follow the same working rules. A government infrastructure project might observe national holidays, while a private industrial site may have a different workweek. For that reason, each project often requires its own calendar setup.

Creating a dedicated project calendar ensures your schedule aligns with:

Actual site workdays
Project-specific shift hours
Holiday breaks
Friday/Sunday weekends depending on the country
Ramadan hours or seasonal adjustments

By tailoring calendars at the project level, you avoid conflicts with other projects and protect your schedule from global changes that may not apply.

Difference Between Global Calendars and Project Calendars

Primavera P6 offers three types of calendars:

Global Calendars: Available across all projects in the database. These are typically set up by an administrator and used for standardization.
Project Calendars: Created specifically within a single project. They’re perfect when your project requires unique working rules.
Resource Calendars: Used to define working hours for specific resources (labor, equipment, etc.), often based on their availability. This can be used if you have a subcontractor carpenter, for example, who works 2 days only. Most of the time, this type of calendar isn’t used in projects to avoid unneeded complexity.

While global calendars can serve as a template, it’s best practice to copy a global calendar into your project and modify it as a project calendar, especially when adding holidays or customizing work hours. This avoids unintentional changes to other projects using the same global calendar.

How to Add Holidays to Project Calendar in P6

To add holidays to P6 calendar (specifically a project calendar), follow these steps:

Open your project in Primavera P6.
Go to Enterprise > Calendars.
Select the appropriate project calendar (or create a new one by copying from a global calendar).
Click Modify to open the calendar settings.
Navigate to the holiday date you want to add.
Double-click the date or click on the day and choose “Work / Non-work”.
Repeat for each year of the project lifecycle, adding 2–3 years extra in case of delays.
Repeat this step for each year of the project lifecycle, and add extra 2-3 years after the project ’s finish date for any delays that might happen later.
Repeat the steps for each holiday in your project calendar.

These holidays will now be excluded from working durations, ensuring your activity finish dates are not miscalculated.

But won’t those steps be a headache for you to do for each project you create in P6? Can’t we define the holidays once and then apply them to each calendar we create later?

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How to Inherit Holidays from a Global Calendar

If your organization maintains a standard holiday list in a global calendar and you want to use those holidays in your project, you don’t need to recreate them manually. Instead, you can inherit holidays from a global calendar into your project calendar.

For example, at Planning Engineer FZE, we work on different schedules from different countries at the same time. Each country has its holidays and working hours for years ahead (e.g., until 2040). So, instead of manually adding holidays to each new calendar, we inherit them from each country’s global calendar.

Go to your project calendar and click Modify.
Under Inherit holidays and exceptions from Global Calendar, choose the desired calendar.
Holidays from the global calendar will have a 🌎 symbol next to them.

You can later modify the project calendar to add extra holidays or project exceptions. This approach ensures that your project benefits from organizational standards while still giving you the flexibility to adjust for local requirements.

Also, most of the projects could have more than one calendar in P6; of course, you don’t want to modify them manually to add holidays in each one of them and forget a day by mistake, that’s when inheriting holidays from a global calendar comes into play.

How to Know Holidays in Any Country?

As a planning engineer, you may find yourself working on projects in unfamiliar regions or supporting a global PMO responsible for projects across multiple countries. One of the practical challenges in such cases is determining the correct list of national and public holidays for the country where the project is located. As we discussed before, these holidays have a direct impact on your Primavera P6 calendar setup and your schedule accuracy.

Here are a few reliable ways to find and validate holiday dates for any country:

1. Check the Project Documents

Before doing any external research, refer to your project documentation. The planning requirements section of the RFP or contract documents often includes a predefined list of holidays or refers to a local labor law or authority that governs public holidays. These should be your primary reference when building your calendar.

2. Refer to Older or Similar Projects

If your organization has previously executed projects in the same country (or even with the same client), review the calendars used in those schedules. This can save you time and give you a validated list of holidays already approved in a past baseline or schedule submission.

3. Use Trusted Online Sources

If no official list is available in project documents, you can search online. Google searches such as “public holidays in [country] 2025” can lead you to reliable sources. Recommended websites include:

Also check government or embassy websites. They often differentiate between fixed and variable holidays.

4. Use AI Tools (with Caution)

AI platforms like ChatGPT can quickly provide a list of holidays for a given country and year. However, it’s always best to validate these responses by cross-checking with official or client-approved sources. AI can accelerate the process but should not be your only source of truth.

Special Note: Religious Holidays

Holidays such as Eid al-Fitr and Eid al-Adha are based on the lunar calendar and can vary by a day depending on moon sightings in each country. It’s best to allow flexibility in your calendar for such holidays by:

Consult local announcements before the holiday
Avoid tight deadlines immediately after expected dates
Add a note in your schedule explaining their flexibility

If you found this guide helpful, don’t forget to explore our Primavera P6 tutorials, which will teach you everything you need to know about planning and scheduling using Primavera P6.

If you’re interested in expanding your knowledge beyond how to add holidays to P6 calendar, we’ve got you covered with more valuable resources. You can read our detailed guide on how to copy a project calendar from one project to another, which walks you through the process of transferring calendar setups efficiently between different projects without starting from scratch. We also recommend checking out our article on Primavera P6 Calendar: 10 Tips and Tricks, where we share expert-level insights to help you get the most out of your calendar configurations, avoid common difficulties, and work smarter within P6.

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