Finding Your PVC Pipe Size

Determining what size PVC pipe you are using in your project or that you picked up from the home center can be a frustrating and challenging process. FORMUFIT products are available in six (6) PVC sizes that work with FORMUFIT PVC pipe, but also work with off-the-shelf plumbing grade PVC pipe, available from your home center or hardware store. You can use PVC pipe machine to produce PVC pipe.

If you have not worked with PVC pipe before, or are not familiar with how PVC pipes are sized, we highly recommend you review the following three important details about PVC Pipe sizing:

The Outside Diameter is not the PVC Pipe Size.

PVC Schedule is Important

Some Pipe isn't Compatible

The Outside Diameter of the pipe is not the PVC Pipe Size.

PVC Pipe sizes are so named by the measurement of the inside diameter (also called the bore) of the PVC pipe, and not the outside diameter. If you measure the outside diameter it will give you a larger reading than the actual PVC Pipe Size. The pipe will always be larger on the outside than the size name, as the thickness of the ‘walls’ of the pipe make it larger.

Correct way to Measure

FORMUFIT products follow the Nominal Pipe Size (NPS) naming convention or PVC specifications, which identifies the diameter of the hole of a PVC pipe with a closely-related dimensional number for its size. Therefore the Pipe Size for all of our products is based on the inside hole or ‘bore’ of the PVC pipe that it fits. This is the correct way to measure what PVC Pipe Size you need.

Incorrect way to Measure

You should never use the outside diameter of the pipe to determine your PVC pipe size. If you measure the outside diameter of your PVC pipe and order based off that measurement you will almost always receive the next PVC Size up. Never order PVC products based off the outside diameter.

Important: PVC Schedule

PVC Schedule (abbrev. SCH or Sch.) is the thickness of the PVC pipe wall. The most common Schedule is 40, but Schedule 80 PVC is also available. As the schedule gets larger the pipe wall gets thicker from the outside in, so the inside hole (bore) of the pipe gets smaller.

FORMUFIT internal-fit products, such as Internal Dome Caps, Adjustable Elbows and Internal Couplings are only compatible with Schedule 40 PVC pipe. All FORMUFIT Furniture Grade PVC pipe is Schedule 40. Our internal-fit products will not work with PVC Schedule 80, as the inner diameter of 80 Schedule PVC is much smaller than PVC Schedule 40.

All off-the-shelf pressurized plumbing-grade PVC pipe is marked with the pipe schedule. Please see our PVC Pipe Markings Page to learn how to read them.

Some Pipe isn't Compatible

Not all types of pipe will work with FORMUFIT fittings and accessories:


The most commonly confused non-compatible pipe is Copper Tube Size (CTS) plastic pipe, which is actually made from CPVC and uses an entirely different sizing system. If you use CTS pipe with FORMUFIT fittings or accessories they will be much too large for the pipe. CTS and CPVC can be identified by their yellowish or tan color, and are marked in the manufacturer printings as CTS or CPVC. For more information on CPVC, please see our CPVC Incompatibilities page here.

ABS Pipe

While ABS pipe is size-compatible with most FORMUFIT products, it cannot be cemented together using standard PVC cement. A special transitional cement must be used, or the pipe to fitting connection must be screwed together to connect them securely. ABS pipe is also very brittle and is not recommended for structural use.

Steel Conduit or Pipe

Steel pipe and conduit have the same outside diameters as the corresponding PVC pipe sizes and are size-compatible, but are not recommended for use with PVC joints & fittings, as there is no way to connect the steel pipe to the plastic PVC fitting. In most cases the steel pipe will easily slide out of the fitting, resulting in loose, or possibly collapsing, structures.

Ground Protection Mats for the Change in Season

Summer is coming to a close across much of the country where heatwaves are giving way to cooler temps and wetter weather. With the change of seasons, now is a great time to outfit your crews with the ground protection mat they need to keep working in the soggy conditions fall has to offer. Using professional ground protection mats helps you avoid unnecessary repair and replacement costs, complete job after job with happy customers, and enjoy a profitable bottom line at the end of the day.

Faster Work and Happier Customers

No question, you need to get the job done when planned, but wet environments can prevent you from starting the work. Using quality ground protection mats can get you in sooner and keep your schedule on track. Especially when the solution is lightweight, easy to deploy, dependable, and can support loads up to 120 tons.

You also want happy customers that refer their friends and contacts, not upset customers who call because of a torn up yard and have negative lasting memory of your work.

Plastic Pipe Machine

As an important part of chemical building materials, plastic pipes are widely accepted by users for their superior performance, hygiene, environmental protection, and low consumption. They mainly include UPVC drainage pipes, UPVC water supply pipes, aluminum-plastic composite pipes, and polyethylene (PE). These kinds of water supply pipes. The pipe production line is composed of a control system, an extruder, a machine head, a shaping cooling system, a tractor, a planetary cutting device and a turning frame. Each pipe production line has two extruders, one of which mainly uses powerful conveying bushings and high-efficiency screws, and the other smaller extruder is used to extrude the marking line. When the plastic pipe machine malfunctions, it will directly cause the plastic pipe to have rough surface, jitter ring inside, and no vacuum. Therefore, it is necessary to eliminate the plastic pipe machine fault in time to improve product quality.

HDPE pipe Machine

HDPE (High Density Polyethylene) water supply pipe, the raw material is from Sinopec. High density polyethylene is non-toxic and odorless milky white particles. It has excellent temperature resistance and cold resistance, good chemical reliability, ductility and impact toughness. Well, it is a kind of thermoplastic resin with high crystallinity and non-polarity. HDPE pipe is a new type of water supply pipe, which can be made by HDPE pipe machine. Its various aspects are better than common traditional drainage pipes, such as cement pipes, cast iron pipes, seamless steel pipes and so on. With the development of high-tech standards, HDPE pipes have become a fashion trend in the future development of the pipeline industry and will completely replace traditional water supply pipes.

PP Pipe Machine

PP pipe is made of polypropylene as raw material and made by PP pipe machine. It is non-toxic, hygienic, high temperature resistant and recyclable. It is mainly used in indoor cold and hot water supply systems in buildings, and is also widely used in heating systems. It has the characteristics of non-corrosion, and can withstand the pH value in a wide temperature range, ranging from 1 to 14 high-concentration acid and alkali corrosion. In addition, the PP pipe is wear-resistant, non-scaling, the inner wall of the pipe and pipe fittings is uniform and smooth, and the flow resistance is small and does not scale. It also has the characteristics of reducing vibration and noise, and has excellent sound insulation performance, which can significantly reduce vibration and noise caused by liquid flow. The P material has excellent elasticity so that the pipe and pipe section can expand with the frost heaving liquid without bursting. The PP tube is anti-condensation and has less heat loss. The PP material is a poor heat conductor, which can reduce condensation and reduce heat loss. It is easy to install, light in weight, easy to install and operate, weldable, and has a long service life. The PP pipe system has a service life of 50 years under specified conditions.

PPR pipe Machine

PPR is the abbreviation of type three polypropylene, also called random copolymer polypropylene pipe. It adopts thermal welding method, has special welding and cutting tools, has high plasticity, and can be made by PPR pipe machine. The price is also very economical. With an external insulation layer, the insulation performance is better, and the pipe wall is also very smooth, excluding the joints of the inner and outer wires. It is generally used in embedded walls or deep well embedded pipes. PPR pipe is moderately priced, stable in performance, heat-resistant, heat-insulated, corrosion-resistant, smooth inner wall, no scaling, safe and reliable piping system, impermeable, and the service life can reach 50 years. However, the construction technology requirements are high, and special tools and professionals are required for construction to ensure the safety of the system.