API tubing sizes are standardized by the API 5CT specification. Tubing is measured by its Outer Diameter (OD), and unlike casing, it is the pipe through which oil and gas actually flow to the surface.
While API recognizes sizes from 1.050" to 4-1/2", the vast majority of oil and gas wells use three "standard" sizes.
Looking for 2-3/8" or 2-7/8" tubing? Check our real-time stock for immediate dispatch.
API Standard Tubing Sizes & Weights Chart
| Outer Diameter (OD) | Nominal Weight | Wall Thickness | Inner Diameter (ID) | Drift Diameter |
| inch (mm) | lb/ft ( kg/m ) | inch (mm) | inch (mm) | inch (mm) |
| 1.050" (26.67) | 1.14 (1.70) | 0.113 (2.87) | 0.824 (20.93) | 0.730 (18.54) |
| 1.315" (33.40) | 1.70 (2.53) | 0.133 (3.38) | 1.049 (26.64) | 0.955 (24.26) |
| 1.660" (42.16) | 2.30 (3.42) | 0.140 (3.56) | 1.380 (35.05) | 1.286 (32.66) |
| 1.900" (48.26) | 2.75 (4.09) | 0.145 (3.68) | 1.610 (40.89) | 1.516 (38.51) |
| 2-3/8" (60.32) | 4.60 (6.85) | 0.190 (4.83) | 1.995 (50.67) | 1.901 (48.29) |
| 2-7/8" (73.02) | 6.40 (9.52) | 0.217 (5.51) | 2.441 (62.00) | 2.347 (59.61) |
| 3-1/2" (88.90) | 9.20 (13.69) | 0.254 (6.45) | 2.992 (76.00) | 2.867 (72.82) |
| 10.20 (15.18) | 0.289 (7.34) | 2.922 (74.22) | 2.797 (71.04) | |
| 4" (101.60) | 9.50 (14.14) | 0.226 (5.74) | 3.548 (90.12) | 3.423 (86.94) |
| 4-1/2" (114.30) | 12.60 (18.75) | 0.271 (6.88) | 3.958 (100.53) | 3.833 (97.36) |
Dimensions and Weight Tolerances
| Item | Specification Range | Tolerance Requirement |
| Outside Diameter (D) |
≤ 4-1/2" (114.3mm) |
± 0.79 mm (0.031") |
| Wall Thickness (t) | All sizes | -12.5% (Upper limit controlled by weight) |
| Individual Weight | All sizes | +6.5% / -3.5% |
| Carload Weight | Order ≥ 18 tons (40,000 lb) | -1.75% |
| Inside Diameter (d) | All sizes | Controlled by OD and Weight tolerances |
Length Ranges
When ordering API tubing, you must specify the Range. Tubing is manufactured in specific length brackets:
Range 1: 20.0 to 24.0 ft (6.10 to 7.32 m)
Range 2: 28.0 to 32.0 ft (8.53 to 9.75 m) - This is the industry standard.
Range 3: 38.0 to 42.0 ft (11.58 to 12.80 m)
Connection (Thread) Types
Size is only half the specification; the thread type determines how the pipes connect:
EUE (External Upset End): The ends of the pipe are thickened (upset) so the threads are stronger than the pipe body. This is the most common connection for API tubing.
NUE (Non-Upset End): The pipe is not thickened at the ends. It is cheaper but has lower joint strength.
Premium Connections: Specialized, gas-tight threads (like TenarisHydril or Vallourec VAM) used for high-pressure or deviated wells.
API 5CT Tubing factory
API 5CT OCTG Test equipments
FAQ
What are standard tubing sizes?
Standard tubing sizes (Outer Diameter) are defined by the API 5CT specification and range from 1.050 inches to 4-1/2 inches.
The most common sizes used in oil and gas production are:
2-3/8" (60.3 mm)
2-7/8" (73.0 mm) - The industry standard for many wells.
3-1/2" (88.9 mm)
4-1/2" (114.3 mm)
What are the grades of API tubing?
API 5CT tubing is categorized into several grades based on strength and service environment:
Low Strength (Shallow Wells): H40, J55, K55. (Economical, standard use).
Medium Strength: N80 (N80-1 or N80-Q). (General high-pressure use).
Corrosion Resistant (Sour Service): L80, C90, T95, C110. (Controlled hardness to resist H2S cracking).
High Strength (Deep/High-Pressure): P110, Q125. (Maximum load-bearing capacity).
