To calculate the area of an irregular pentagon, we'll need one of the following:

1. The coordinates of its vertices.
2. A decomposition of the pentagon into smaller, simpler shapes like triangles or trapezoids with their respective dimensions.
3. A given formula or additional measurements like diagonals or side lengths with heights.

If you have any of the above information or can upload an image with dimensions, please provide it so I can assist further. Would you like to clarify or upload the details?

Here are some questions for you to consider:

1. Do you know the side lengths and angles of the pentagon?
2. Is the pentagon divided into simpler shapes?
3. Are the vertices' coordinates provided in a Cartesian plane?
4. Is this a practical problem with real-world units?
5. Would you like help in approximating the area if dimensions are incomplete?

Tip: For irregular polygons, breaking them into triangles is often the easiest way to calculate the area.