What can make the process more confusing is that for some post diameters, such as 1 5/8' and 4', the actual and nominal diameters are the same. A circle of radius 1.25 or diameter 2.5 or area 4.909 inches has a circumference of 7.854 inches which is equal to: Use the this circumference length calculator above to find the perimeter of a circle given its diameter, or other parameters. If you are buying that 2' post cap, you would need to measure and make sure your post has an outside diameter of 1 7/8'. In the building industry, nominal dimensions are the terms that are used most often, such as a 2' post cap, while actual dimensions are the true measurements of a post, which in this example would be 1 7/8'. It's important to understand the differences between nominal and actual sizes of posts. It can be confusing when a post cap, for example, is listed as 2', but with a 1 7/8' Actual OD (Outside Diameter). Pipe Schedules (Wall Thickness): Fence Industry Standard (O.D.) in fraction form as the primary measurement. Usually, the fence industry will use the actual O.D. The measurement of a pipe's schedule does not indicate the pipe's diameter.

Popular pipe schedules are Schedule 10, 40, and 80. Pipe wall thickness is measured by pipe schedules. The gauge measurement is consistent across various tube sizes. For example, a 10-gauge wall is thicker than a 16-gauge wall. Tube wall thickness is measured in gauge the lower the gauge, the thicker the wall. Beside is a diagram to illustrate the role that wall thicknesses or gauges play in the diameter of a pipe or tube measurement.Īlthough the terms post and tube can sometimes be used interchangeably, there are differences between the two, especially when it comes to how diameter and wall thickness are measured. As the schedule number increases, so does the thickness of the pipe. Schedule 40 is the most common pipe schedule, which describes the thickness of a pipe. The difference between the inside and outside diameter for a post is the wall thickness of a post or rail. Internal-fitting items should fit snugly inside the post, forming a tight connection that keeps moisture and pests out. Finding the inside diameter means measuring from the inside of a post's wall, directly across to the inside of the wall opposite your first measuring point. That's why using a chart and understanding how PVC pipe sizes are measured is important. For instance you might assume a pipe with OD (outer diameter) of 1.660' is a 1-1/2' size pipe when in fact it is 1-1/4' size. You'll notice, without a chart the dimensions could be deceiving.

The inside diameter pertains to internal-fitting objects, such as post plugs. Our online actual size ruler allows you to take measurements in millimeters, centimeters and inches all at once, giving you the most accurate information. This chart includes sizes from 1/2' to 10'. The outside diameter is relevant for external-fitting objects like external post caps. To find the outside diameter, measure from the outside edge of the post's wall directly across to the inside edge on the opposite side. A post, which has either a square or circular shape, has an inside diameter and an outside diameter.

2 inch diameter actual size