PEX Pipe Sizes Chart
Complete reference chart for CTS (Copper Tube Size) PEX tubing dimensions. Find OD, ID, wall thickness, and flow area for all standard sizes per ASTM F876/F877.
PEX Tubing Size Chart (CTS - Copper Tube Size)
Standard residential PEX tubing dimensions. CTS sizing uses actual outside diameter (like copper), not Nominal Pipe Size (NPS). All PEX types (A, B, C) share the same CTS dimensions.
| Nominal Size | OD (in) | OD (mm) | ID (in) | ID (mm) | Wall (in) | Wall (mm) | Area (in²) |
|---|---|---|---|---|---|---|---|
| 3/8" | 0.500" | 12.70 | 0.360" | 9.14 | 0.070" | 1.78 | 0.102 |
| 1/2" | 0.625" | 15.88 | 0.485" | 12.32 | 0.070" | 1.78 | 0.185 |
| 5/8" | 0.750" | 19.05 | 0.610" | 15.49 | 0.070" | 1.78 | 0.292 |
| 3/4" | 0.875" | 22.23 | 0.709" | 18.01 | 0.083" | 2.11 | 0.395 |
| 1" | 1.125" | 28.58 | 0.959" | 24.36 | 0.083" | 2.11 | 0.722 |
| 1-1/4" | 1.375" | 34.93 | 1.189" | 30.20 | 0.093" | 2.36 | 1.110 |
| 1-1/2" | 1.625" | 41.28 | 1.439" | 36.55 | 0.093" | 2.36 | 1.626 |
| 2" | 2.125" | 53.98 | 1.913" | 48.59 | 0.106" | 2.69 | 2.874 |
Standard: ASTM F876/F877 - CTS (Copper Tube Size) Standard Residential PEX Tubing
About PEX Tubing & CTS Sizing
PEX (Crosslinked Polyethylene) is a flexible plastic tubing used for hot and cold water distribution in residential and commercial plumbing systems. Unlike steel pipe which uses Nominal Pipe Size (NPS), PEX uses CTS (Copper Tube Size) which represents the actual outside diameter.
CTS Sizing (PEX Standard)
- Definition: Copper Tube Size - actual OD measurement
- Example: 1/2" PEX has 0.625" actual OD (same as 1/2" copper)
- Wall Thickness: Standard residential wall thickness for each size
- Compatibility: Direct replacement for copper tubing in many applications
- Benefits: Consistent sizing makes transitions to copper fittings easier
PEX Manufacturing Process
- Material: High-density polyethylene (HDPE) polymer
- Crosslinking: Chemical bonds create 3D molecular network
- Result: Superior strength, flexibility, and temperature resistance
- Properties: Won't crack, corrode, or scale like metal pipes
- Flexibility: Can bend around corners, reducing fittings needed
Important Note on CTS vs NPS:
PEX tubing uses CTS (Copper Tube Size) where the nominal size represents the actual outside diameter. For example, 3/4" PEX has an actual OD of 0.875 inches, matching 3/4" copper tube. This differs from steel pipe NPS (Nominal Pipe Size) where 3/4" refers to an approximate internal bore, not the actual OD.
How to Read This Chart
Column Definitions
- Nominal Size
- The CTS designation (e.g., 1/2", 3/4", 1"). For PEX, this represents the actual outside diameter and matches copper tube sizing. A 1/2" PEX tube has the same OD as 1/2" copper tube.
- OD (Outside Diameter)
- Actual external diameter of the tubing. This is the CTS standard dimension and matches copper tubing OD. Critical for selecting compression fittings and determining pipe support sizing. Shown in both inches and millimeters.
- ID (Inside Diameter)
- Internal diameter available for fluid flow. Calculated as: ID = OD - (2 × Wall Thickness). Used for flow rate and velocity calculations. Shown in both inches and millimeters.
- Wall Thickness
- Thickness of the tubing wall. Standard residential PEX uses consistent wall thickness for each size. Thicker walls provide higher pressure ratings and better freeze resistance. Shown in both inches and millimeters.
- Area (Flow Area)
- Cross-sectional area available for fluid flow, calculated as π × (ID/2)². Used in flow rate, velocity, and pressure drop calculations. Shown in square inches.
How to Select the Right PEX Size
- Determine fixture flow requirements - Calculate total GPM demand for all fixtures served by the line. Common sizes: 3/8" (1-2 GPM), 1/2" (4-5 GPM), 3/4" (8-10 GPM), 1" (15-20 GPM).
- Consider pipe run length - Longer runs require larger diameter to maintain adequate pressure. Use our Pressure Drop Calculator to verify pressure loss.
- Check velocity limits - Residential plumbing: 4-8 ft/s typical, 10 ft/s maximum. Higher velocities cause noise and erosion. Use our Velocity Calculator to verify.
- Review pressure rating requirements - Standard residential PEX is rated for 160 PSI at 73°F, 100 PSI at 180°F. Apply temperature de-rating for hot water applications.
- Verify code compliance - Check local plumbing codes for minimum and maximum sizes. Some jurisdictions restrict PEX to certain applications or require specific types (A, B, or C).
PEX Tubing Types (A, B, C)
All PEX types (A, B, and C) share the same CTS dimensions shown in this chart. The difference is in the crosslinking method used during manufacturing, which affects flexibility, kink resistance, and price - but not the actual pipe dimensions.
PEX-A (Engel Method)
- Crosslinking: Peroxide method during manufacturing (highest degree)
- Flexibility: Most flexible, easiest to work with
- Kink Resistance: Best - can be re-rounded with heat gun if kinked
- Freeze Resistance: Best expansion/contraction performance
- Fittings: Expansion (cold expansion) fittings - largest flow area
- Cost: Most expensive
- Brands: Uponor (Wirsbo), Rehau
- Best For: Premium installations, tight bends, freeze-prone areas
PEX-B (Silane Method)
- Crosslinking: Silane method after extrusion (medium degree)
- Flexibility: Good flexibility, slight coil memory
- Kink Resistance: Good - kinks cannot be repaired (must cut out)
- Freeze Resistance: Good performance in freeze conditions
- Fittings: Crimp, clamp, or push-fit fittings
- Cost: Mid-range, most economical for quality
- Brands: Zurn, SharkBite, Apollo, most manufacturers
- Best For: General residential plumbing, best value
PEX-C (E-Beam Method)
- Crosslinking: Electron beam irradiation after extrusion (lowest degree)
- Flexibility: Less flexible, more rigid, stiffer coil memory
- Kink Resistance: Lower - more prone to kinking
- Freeze Resistance: Adequate for most applications
- Fittings: Crimp, clamp, or barb fittings
- Cost: Least expensive
- Brands: Various budget brands
- Best For: Budget projects, straight runs, DIY installations
Key Takeaway:
All three PEX types (A, B, C) use the same CTS dimensions from this chart. Your choice of type affects flexibility, installation ease, and cost - not the pipe size or flow capacity. PEX-B offers the best balance of performance and value for most residential applications.
PEX Applications
Residential Plumbing
- Hot and cold water distribution systems
- Whole-house plumbing manifold systems
- Individual fixture supply lines (home runs)
- Water heater connections and recirculation loops
- Bathroom and kitchen rough-in plumbing
- Washing machine and appliance hookups
- Outdoor hose bibs and irrigation supply
- Replacement for copper in remodeling projects
Radiant Heating Systems
- In-floor radiant heating (most common application)
- Basement and garage floor heating loops
- Bathroom and kitchen floor warming systems
- Driveway and sidewalk snow melt systems
- Outdoor step and walkway ice prevention
- Hydronic baseboard heating distribution
- Pool and spa heating systems
- Commercial building radiant panel systems
Commercial & Specialty
- Multi-family residential plumbing systems
- Hotels and hospitality water distribution
- Institutional buildings (schools, hospitals)
- Residential fire sprinkler systems (CPVC-approved areas)
- Commercial kitchen and restaurant plumbing
- Reclaimed water distribution systems
- Solar thermal hot water systems
- Geothermal heating/cooling ground loops
PEX Advantages
- Flexibility: Reduces fittings, speeds installation
- Freeze Resistance: Can expand without bursting
- Corrosion Resistance: Won't corrode, pit, or scale
- Quiet Operation: Eliminates water hammer noise
- Lower Cost: Less expensive than copper
- Fewer Joints: Long continuous runs reduce leak points
- Chemical Resistance: Resists chlorine and hard water
- Energy Efficient: Less heat loss than metal pipes
Application Restrictions:
PEX cannot be used outdoors or exposed to sunlight (UV degrades plastic), cannot be used with recirculating pumps over 140°F continuous duty, and is not approved for direct connection to water heaters (use 18" copper stub-outs). Some local codes restrict PEX use - always verify code compliance before installation.
Temperature & Pressure Ratings
Operating Temperature Ranges
Continuous Operating Range
- Minimum: -40°F (-40°C) - maintains flexibility in freezing conditions
- Maximum Continuous: 180°F (82°C) at reduced pressure rating
- Optimal Range: 32°F to 140°F (0°C to 60°C) for full pressure rating
- Standard Rating: 73°F (23°C) at 160 PSI for 50-year service life
Surge/Short-Term Ratings
- Maximum Surge: 200°F (93°C) for brief periods only
- Duration: Short-term exposure (<1 hour) acceptable
- Pressure Surge: Can handle brief pressure spikes above rating
- Recovery: Returns to original shape after cooling
Pressure Ratings by Temperature
| Temperature | Pressure Rating (PSI) | Application |
|---|---|---|
| 73°F (23°C) | 160 PSI | Cold water distribution, standard rating |
| 100°F (38°C) | 130 PSI | Warm water applications |
| 140°F (60°C) | 100 PSI | Standard hot water distribution |
| 180°F (82°C) | 100 PSI | Maximum continuous hot water temperature |
| 200°F (93°C) | 80 PSI | Short-term surge only (<1 hour) |
Chlorine Resistance
PEX tubing is tested for chlorine resistance per ASTM F2023 and CSA B137.5 standards. Standard PEX can handle typical municipal chlorine levels (0.5-4.0 ppm) at elevated temperatures for 50-year service life.
- Standard Chlorine (1-2 ppm): No degradation over 50+ years at 140°F
- High Chlorine (3-4 ppm): Minimal impact on service life with proper installation
- Enhanced Formulations: Some PEX types offer improved chlorine resistance
- Temperature Impact: Higher temperatures accelerate chlorine aging effects
Standards & Specifications
Primary Standards
ASTM F876 - Crosslinked Polyethylene (PEX) Tubing
Standard specification for crosslinked polyethylene (PEX) tubing. Defines material requirements, dimensions, burst pressure, sustained pressure, and quality control testing for PEX tubing intended for pressure applications.
- CTS dimensions (Copper Tube Size) as shown in this chart
- Minimum burst pressure: 480 PSI at 73°F for CTS sizes
- Minimum sustained pressure: 160 PSI at 73°F for 50-year service life
- Hot water rating: 100 PSI at 180°F continuous
ASTM F877 - Crosslinked Polyethylene (PEX) Hot/Cold Water Distribution
Standard specification for crosslinked polyethylene (PEX) plastic hot and cold water distribution systems. Covers complete system including tubing, fittings, manifolds, and installation methods.
- System design and layout requirements
- Fitting compatibility and pressure ratings
- Installation methods and support spacing
- Expansion/contraction calculations and allowances
ASTM F2023 - PEX for Radiant Floor Heating
Standard for crosslinked polyethylene (PEX) tubing used in radiant floor heating and snow melting systems. Addresses elevated temperature exposure and chlorine resistance for hydronic applications.
NSF/ANSI 61 - Drinking Water System Components
Health effects standard for drinking water system components. All PEX tubing for potable water must be certified to NSF/ANSI 61 to ensure no harmful contaminants leach into drinking water.
Color Coding
Red PEX
Designated for hot water distribution. Standard color coding for hot water manifold systems and individual hot water supply lines.
Blue PEX
Designated for cold water distribution. Standard color coding for cold water manifold systems and individual cold water supply lines.
White PEX
Can be used for either hot or cold water. Common for radiant heating loops and applications where color coding is not required.
Note: Color coding is for identification purposes only. Red, blue, and white PEX have identical physical properties and pressure ratings. All colors share the same CTS dimensions from this chart.
Fitting Systems
Crimp Fittings (Most Common)
Copper or stainless steel crimp ring compressed over PEX using crimp tool. Requires go/no-go gauge verification. Compatible with PEX-B and PEX-C. Economical and reliable method.
Expansion Fittings (PEX-A Only)
Fitting is inserted into expanded PEX-A tubing which shrinks back to original size. Largest internal flow area, no metal rings visible. Requires expansion tool. Premium method for PEX-A systems.
Clamp (Cinch) Fittings
Stainless steel clamp band tightened with clamp tool. Easier to verify than crimp rings (visible tab). Works with all PEX types. Popular for repairs and remodeling.
Push-Fit Fittings
No tools required - push tubing into fitting until it locks. Removable and reusable. More expensive than crimp/clamp but fastest installation. Common brands: SharkBite, ProBite.
Related Calculators
Engineering Notes & Disclaimer
Standards Compliance: All dimensions in this chart are based on ASTM F876 and F877 (Crosslinked Polyethylene Tubing and Hot/Cold Water Distribution Systems) using CTS (Copper Tube Size) standard.
Pressure Ratings: Standard residential PEX is rated for 160 PSI at 73°F, 100 PSI at 180°F. Pressure ratings decrease at elevated temperatures. Always apply appropriate temperature de-rating factors.
Temperature Limits: Maximum continuous operating temperature is 180°F (82°C). Brief exposure to 200°F is acceptable. Optimal performance range is 73°F to 140°F. Do not use for steam or high-temperature industrial applications.
Expansion/Contraction: PEX has a thermal expansion coefficient of 0.000094 in/in/°F (nearly 10× greater than copper). Provide adequate allowance for expansion through flexible routing, expansion loops, or offset changes in direction.
UV Degradation: PEX degrades rapidly when exposed to UV light (sunlight). Never install PEX outdoors or in direct sunlight. Use only indoors or in buried applications protected from sunlight.
Fitting Compatibility: Use only fittings approved for the specific PEX type (A, B, or C). Expansion fittings require PEX-A. Crimp/clamp fittings work with PEX-B and PEX-C. Always follow manufacturer installation instructions.
Code Compliance: Verify local plumbing code approval before installation. Some jurisdictions restrict PEX to certain applications or require specific types. International codes (IPC, UPC) generally accept PEX per ASTM standards.
Water Heater Connections: Most codes require 18" of metal pipe (copper or CPVC) between water heater and PEX connection to protect from excessive temperatures. Never connect PEX directly to water heater.
Support Spacing: Support PEX tubing per ASTM F877: horizontal runs every 32 inches, vertical runs every 4-6 feet. Provide additional support at changes in direction and near fittings.
Professional Verification: This chart is for reference and preliminary design only. All plumbing systems must be designed, installed, and inspected by qualified professionals in accordance with applicable codes, standards, and local regulations. Always verify dimensions and specifications with manufacturer data sheets.
Liability: The user assumes all responsibility for proper application of this information. PipeSizing.net and its operators are not liable for any damages or losses resulting from the use of this chart.