The density of FR4 material is approximately 1.85 g/cm³. This is an average value, and the exact density can vary slightly depending on the specifics of the FR4 formulation used.

To calculate the weight of the FR4 board, follow these steps:

1. First, you need to calculate the volume of the FR4 board. This can be done using the formula for the volume of a rectangular prism: Volume = length x width x thickness. Be sure that all your measurements are in the same units. If your length and width are given in millimeters and thickness in inches, you will need to convert them all to the same unit. In this case, it’s best to use centimeters because the density of FR4 is given in grams per cubic centimeter (g/cm³).

2. Once you have calculated the volume (in cubic centimeters), you can calculate the weight. Multiply the volume by the density of FR4 to get the weight in grams. Weight = volume x density.

Remember, these calculations will give you an approximate value. The actual weight can vary slightly based on factors such as variations in the material’s density, manufacturing tolerances, etc.