Diameter height length is given how to find volume of cylinder laid horizontally?

Whether a cylinder is laid horizontally, or standing vertically, it has the same volume.

The volume of a cylinder is the 'square area' of the circle at the end, multiplied by its length/height.

The area of a circle is Pi x diameter. (The inner diameter is probably best. The final calculation will then show the total internal volume in cubic units.)

End area x length = volume.

If the cylinder is laid horizontally, the distance between the ends would be called its length. If the cylinder is standing up, the distance between the ends is called its height.