Choosing the right fitting size is essential for maintaining proper pressure, preventing leaks, and ensuring safety. However, with multiple fitting standards like JIC, NPT, ORFS, BSP, and Metric, determining the correct size can be confusing.
This detailed guide provides a complete Hydraulic Fitting Size Chart that covers all major fitting types, thread sizes, and corresponding hose sizes to help you identify the correct part quickly.
Hydraulic Fitting Size Chart
NPTF (National Pipe Tapered Fuel)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | NPTF | 1/8 | 27 | Tapered | 13/32 (0.41) | 3/8 (0.38) |
| 1/4 | -4 | 1/4 | NPTF | 1/4 | 18 | Tapered | 17/32 (0.54) | 1/2 (0.49) |
| 3/8 | -6 | 3/8 | NPTF | 3/8 | 18 | Tapered | 11/16 (0.68) | 5/8 (0.63) |
| 1/2 | -8 | 1/2 | NPTF | 1/2 | 14 | Tapered | 27/32 (0.84) | 25/32 (0.77) |
| 3/4 | -12 | 3/4 | NPTF | 3/4 | 14 | Tapered | 1 1/16 (1.05) | 1 (0.98) |
| 1 | -16 | 1 | NPTF | 1 | 11.5 | Tapered | 1 5/16 (1.32) | 1 1/4 (1.24) |
| 1 1/4 | -20 | 1 1/4 | NPTF | 1 1/4 | 11.5 | Tapered | 1 21/32 (1.66) | 1 19/32 (1.58) |
| 1 1/2 | -24 | 1 1/2 | NPTF | 1 1/2 | 11.5 | Tapered | 1 29/32 (1.90) | 1 13/16 (1.82) |
| 2 | -32 | 2 | NPTF | 2 | 11.5 | Tapered | 2 3/8 (2.38) | 2 5/16 (2.30) |
Related Oil Drain Plug Torque Chart(For ALL Car Models)
NPSM (National Pipe Straight Mechanical)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | NPSM | 1/8 | 27 | Straight | 13/32 (0.41) | 3/8 (0.38) |
| 1/4 | -4 | 1/4 | NPSM | 1/4 | 18 | Straight | 17/32 (0.54) | 1/2 (0.49) |
| 3/8 | -6 | 3/8 | NPSM | 3/8 | 14 | Straight | 11/16 (0.68) | 5/8 (0.63) |
| 1/2 | -8 | 1/2 | NPSM | 1/2 | 14 | Straight | 27/32 (0.84) | 25/32 (0.77) |
| 3/4 | -12 | 3/4 | NPSM | 3/4 | 14 | Straight | 1 1/16 (1.05) | 1 (0.98) |
| 1 | -16 | 1 | NPSM | 1 | 11.5 | Straight | 1 5/16 (1.32) | 1 1/4 (1.24) |
| 1 1/4 | -20 | 1 1/4 | NPSM | 1 1/4 | 11.5 | Straight | 1 21/32 (1.66) | 1 19/32 (1.58) |
| 1 1/2 | -24 | 1 1/2 | NPSM | 1 1/2 | 11.5 | Straight | 1 29/32 (1.90) | 1 13/16 (1.82) |
| 2 | -32 | 2 | NPSM | 2 | 11.5 | Straight | 2 3/8 (2.38) | 2 5/16 (2.30) |
Related Hydraulic Oil Equivalent Chart(For All Brands)
JIC 37° Flare (SAE J514)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | UNF | 5/16-24 | 24 | 37° | 5/16 (0.31) | 9/32 (0.27) |
| 3/16 | -3 | 3/16 | UNF | 3/8-24 | 24 | 37° | 3/8 (0.38) | 11/32 (0.34) |
| 1/4 | -4 | 1/4 | UNF | 7/16-20 | 20 | 37° | 7/16 (0.44) | 13/32 (0.39) |
| 5/16 | -5 | 5/16 | UNF | 1/2-20 | 20 | 37° | 1/2 (0.50) | 15/32 (0.45) |
| 3/8 | -6 | 3/8 | UNF | 9/16-18 | 18 | 37° | 9/16 (0.56) | 17/32 (0.51) |
| 1/2 | -8 | 1/2 | UNF | 3/4-16 | 16 | 37° | 3/4 (0.75) | 11/16 (0.69) |
| 5/8 | -10 | 5/8 | UNF | 7/8-14 | 14 | 37° | 7/8 (0.88) | 13/16 (0.81) |
| 3/4 | -12 | 3/4 | UNF | 1 1/16-12 | 12 | 37° | 1 1/16 (1.06) | 1 (0.98) |
| 7/8 | -14 | 7/8 | UNF | 1 3/16-12 | 12 | 37° | 1 3/16 (1.19) | 1 1/8 (1.10) |
| 1 | -16 | 1 | UNF | 1 5/16-12 | 12 | 37° | 1 5/16 (1.31) | 1 1/4 (1.23) |
| 1 1/4 | -20 | 1 1/4 | UNF | 1 5/8-12 | 12 | 37° | 1 5/8 (1.63) | 1 9/16 (1.54) |
| 1 1/2 | -24 | 1 1/2 | UNF | 1 7/8-12 | 12 | 37° | 1 7/8 (1.88) | 1 13/16 (1.79) |
| 2 | -32 | 2 | UNF | 2 1/2-12 | 12 | 37° | 2 1/2 (2.50) | 2 7/16 (2.42) |
Related Hydraulic Oil vs Engine Oil(Complete Side by Side Differences)
SAE 45° Flare (SAE J512)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | UNF | 5/16-24 | 24 | 45° | 5/16 (0.31) | 9/32 (0.27) |
| 3/16 | -3 | 3/16 | UNF | 3/8-24 | 24 | 45° | 3/8 (0.38) | 11/32 (0.34) |
| 1/4 | -4 | 1/4 | UNF | 7/16-20 | 20 | 45° | 7/16 (0.44) | 13/32 (0.39) |
| 5/16 | -5 | 5/16 | UNF | 1/2-20 | 20 | 45° | 1/2 (0.50) | 15/32 (0.45) |
| 3/8 | -6 | 3/8 | UNF | 5/8-18 | 18 | 45° | 5/8 (0.63) | 9/16 (0.57) |
| 1/2 | -8 | 1/2 | UNF | 3/4-16 | 16 | 45° | 3/4 (0.75) | 11/16 (0.69) |
| 5/8 | -10 | 5/8 | UNF | 7/8-14 | 14 | 45° | 7/8 (0.88) | 13/16 (0.81) |
| 3/4 | -12 | 3/4 | UNF | 1 1/16-14 | 14 | 45° | 1 1/16 (1.06) | 1 (0.99) |
| 7/8 | -14 | 7/8 | UNF | 1 1/4-12 | 12 | 45° | 1 1/4 (1.25) | 1 5/32 (1.16) |
| 1 | -16 | 1 | UNF | 1 3/8-12 | 12 | 45° | 1 3/8 (1.38) | 1 9/32 (1.29) |
SAE Straight Thread O-Ring (O-Ring Boss) – SAE J1926-1
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | UN/UNF | 5/16-24 | 24 | O-Ring | 5/16 (0.31) | 9/32 (0.27) |
| 3/16 | -3 | 3/16 | UN/UNF | 3/8-24 | 24 | O-Ring | 3/8 (0.38) | 11/32 (0.34) |
| 1/4 | -4 | 1/4 | UN/UNF | 7/16-20 | 20 | O-Ring | 7/16 (0.44) | 13/32 (0.39) |
| 5/16 | -5 | 5/16 | UN/UNF | 1/2-20 | 20 | O-Ring | 1/2 (0.50) | 15/32 (0.45) |
| 3/8 | -6 | 3/8 | UN/UNF | 9/16-18 | 18 | O-Ring | 9/16 (0.56) | 17/32 (0.51) |
| 1/2 | -8 | 1/2 | UN/UNF | 3/4-16 | 16 | O-Ring | 3/4 (0.75) | 11/16 (0.69) |
| 5/8 | -10 | 5/8 | UN/UNF | 7/8-14 | 14 | O-Ring | 7/8 (0.88) | 13/16 (0.81) |
| 3/4 | -12 | 3/4 | UN/UNF | 1 1/16-12 | 12 | O-Ring | 1 1/16 (1.06) | 1 (0.98) |
| 7/8 | -14 | 7/8 | UN/UNF | 1 3/16-12 | 12 | O-Ring | 1 3/16 (1.19) | 1 1/8 (1.10) |
| 1 | -16 | 1 | UN/UNF | 1 5/16-12 | 12 | O-Ring | 1 5/16 (1.31) | 1 1/4 (1.23) |
| 1 1/4 | -20 | 1 1/4 | UN/UNF | 1 5/8-12 | 12 | O-Ring | 1 5/8 (1.63) | 1 9/16 (1.54) |
| 1 1/2 | -24 | 1 1/2 | UN/UNF | 1 7/8-12 | 12 | O-Ring | 1 7/8 (1.88) | 1 13/16 (1.79) |
| 2 | -32 | 2 | UN/UNF | 2 1/2-12 | 12 | O-Ring | 2 1/2 (2.50) | 2 7/16 (2.42) |
Related Oil Filter Thread Size Chart(For All Thread Size/Pitch)
ORFS (O-Ring Face Seal) – SAE J1453
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/4 | -4 | 1/4 | UN/UNF | 9/16-18 | 18 | Flat | 9/16 (0.56) | 17/32 (0.51) |
| 5/16 | -5 | 5/16 | UN/UNF | 5/8-18 | 18 | Flat | 5/8 (0.63) | 9/16 (0.57) |
| 3/8 | -6 | 3/8 | UN/UNF | 11/16-16 | 16 | Flat | 11/16 (0.69) | 5/8 (0.63) |
| 1/2 | -8 | 1/2 | UN/UNF | 13/16-16 | 16 | Flat | 13/16 (0.81) | 3/4 (0.75) |
| 5/8 | -10 | 5/8 | UN/UNF | 1-14 | 14 | Flat | 1 (1.00) | 15/16 (0.94) |
| 3/4 | -12 | 3/4 | UN/UNF | 1 3/16-12 | 12 | Flat | 1 3/16 (1.19) | 1 1/8 (1.13) |
| 7/8 | -14 | 7/8 | UN/UNF | 1 5/16-12 | 12 | Flat | 1 5/16 (1.31) | 1 1/4 (1.25) |
| 1 | -16 | 1 | UN/UNF | 1 7/16-12 | 12 | Flat | 1 7/16 (1.44) | 1 3/8 (1.38) |
| 1 1/4 | -20 | 1 1/4 | UN/UNF | 1 11/16-12 | 12 | Flat | 1 11/16 (1.69) | 1 5/8 (1.63) |
| 1 1/2 | -24 | 1 1/2 | UN/UNF | 2-12 | 12 | Flat | 2 (2.00) | 1 15/16 (1.94) |
| 2 | -32 | 2 | UN/UNF | 2 1/2-12 | 12 | Flat | 2 1/2 (2.50) | 2 7/16 (2.44) |
BSPP (British Standard Pipe Parallel)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | BSPP | G1/8 | 28 | 60° | 0.38 | 0.35 |
| 1/4 | -4 | 1/4 | BSPP | G1/4 | 19 | 60° | 0.52 | 0.47 |
| 3/8 | -6 | 3/8 | BSPP | G3/8 | 19 | 60° | 0.66 | 0.60 |
| 1/2 | -8 | 1/2 | BSPP | G1/2 | 14 | 60° | 0.83 | 0.75 |
| 5/8 | -10 | 5/8 | BSPP | G5/8 | 14 | 60° | 0.90 | 0.82 |
| 3/4 | -12 | 3/4 | BSPP | G3/4 | 14 | 60° | 1.04 | 0.95 |
| 1 | -16 | 1 | BSPP | G1 | 11 | 60° | 1.30 | 1.20 |
| 1 1/4 | -20 | 1 1/4 | BSPP | G1 1/4 | 11 | 60° | 1.65 | 1.55 |
| 1 1/2 | -24 | 1 1/2 | BSPP | G1 1/2 | 11 | 60° | 1.89 | 1.78 |
| 2 | -32 | 2 | BSPP | G2 | 11 | 60° | 2.35 | 2.22 |
Related Engine Oil Consumption Calculator
BSPT (British Standard Pipe Tapered)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | BSPT | R1/8 | 28 | 55° | 0.38 | 0.35 |
| 1/4 | -4 | 1/4 | BSPT | R1/4 | 19 | 55° | 0.52 | 0.47 |
| 3/8 | -6 | 3/8 | BSPT | R3/8 | 19 | 55° | 0.66 | 0.60 |
| 1/2 | -8 | 1/2 | BSPT | R1/2 | 14 | 55° | 0.83 | 0.75 |
| 3/4 | -12 | 3/4 | BSPT | R3/4 | 14 | 55° | 1.04 | 0.95 |
| 1 | -16 | 1 | BSPT | R1 | 11 | 55° | 1.30 | 1.20 |
Metric DIN 24° Cone (DIN 2353 L/S Series)
| Tube OD (mm) | Dash Size | Hose ID (approx) | Thread Type | Thread Size | Thread Pitch (mm) | Seat Angle | Male Thread O.D. (mm) | Female Thread O.D. (mm) |
|---|---|---|---|---|---|---|---|---|
| 6 | -04 | 1/4 | Metric | M12x1.5 | 1.5 | 24° | 12 | 10.5 |
| 8 | -05 | 5/16 | Metric | M14x1.5 | 1.5 | 24° | 14 | 12.5 |
| 10 | -06 | 3/8 | Metric | M16x1.5 | 1.5 | 24° | 16 | 14.5 |
| 12 | -08 | 1/2 | Metric | M18x1.5 | 1.5 | 24° | 18 | 16.5 |
| 14/15 | -10 | 5/8 | Metric | M22x1.5 | 1.5 | 24° | 22 | 20.5 |
| 16 | -12 | 5/8 | Metric | M24x1.5 | 1.5 | 24° | 24 | 22.5 |
| 20 | -14 | 3/4 | Metric | M30x2 | 2.0 | 24° | 30 | 28 |
| 25 | -16 | 1 | Metric | M36x2 | 2.0 | 24° | 36 | 34 |
| 30 | -20 | 1 1/4 | Metric | M42x2 | 2.0 | 24° | 42 | 40 |
| 38 | -24 | 1 1/2 | Metric | M52x2 | 2.0 | 24° | 52 | 50 |
Related Wolf’s Head Super Universal Synthetic ATF Chart(All Models)
Flareless Compression (SAE J514)
| Inch Size | Dash Size | Hose ID (in) | Thread Type | Thread Size | Thread Pitch (TPI) | Seat Angle | Male Thread O.D. (in) | Female Thread O.D. (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | -2 | 1/8 | UN/UNF | 5/16-24 | 24 | Bite | 5/16 (0.31) | 9/32 (0.27) |
| 3/16 | -3 | 3/16 | UN/UNF | 3/8-24 | 24 | Bite | 3/8 (0.38) | 11/32 (0.34) |
| 1/4 | -4 | 1/4 | UN/UNF | 7/16-20 | 20 | Bite | 7/16 (0.44) | 13/32 (0.39) |
| 5/16 | -5 | 5/16 | UN/UNF | 1/2-20 | 20 | Bite | 1/2 (0.50) | 15/32 (0.45) |
| 3/8 | -6 | 3/8 | UN/UNF | 9/16-18 | 18 | Bite | 9/16 (0.56) | 17/32 (0.51) |
| 1/2 | -8 | 1/2 | UN/UNF | 3/4-16 | 16 | Bite | 3/4 (0.75) | 11/16 (0.69) |
| 5/8 | -10 | 5/8 | UN/UNF | 7/8-14 | 14 | Bite | 7/8 (0.88) | 13/16 (0.81) |
| 3/4 | -12 | 3/4 | UN/UNF | 1 1/16-12 | 12 | Bite | 1 1/16 (1.06) | 1 (0.98) |
| 7/8 | -14 | 7/8 | UN/UNF | 1 3/16-12 | 12 | Bite | 1 3/16 (1.19) | 1 1/8 (1.10) |
| 1 | -16 | 1 | UN/UNF | 1 5/16-12 | 12 | Bite | 1 5/16 (1.31) | 1 1/4 (1.23) |
| 1 1/4 | -20 | 1 1/4 | UN/UNF | 1 5/8-12 | 12 | Bite | 1 5/8 (1.63) | 1 9/16 (1.54) |
| 1 1/2 | -24 | 1 1/2 | UN/UNF | 1 7/8-12 | 12 | Bite | 1 7/8 (1.88) | 1 13/16 (1.79) |
| 2 | -32 | 2 | UN/UNF | 2 1/2-12 | 12 | Bite | 2 1/2 (2.50) | 2 7/16 (2.42) |
Related Hydraulic Symbols Chart(All Symbols + Meanings)
How to Identify the Correct Hydraulic Fitting Size
- Measure the Thread Diameter: Use a caliper to measure the outer diameter of male threads or the inner diameter of female threads.
- Determine the Thread Pitch: Use a thread pitch gauge or compare visually with a known fitting.
- Check the Seat Angle: Use a seat gauge or protractor to identify if it’s 37°, 45°, or flat face.
- Match the Standard: Compare your measurements with the chart above to find the correct standard and dash size.
Why Correct Sizing Matters
Choosing the wrong fitting size can cause:
- Fluid leaks under pressure
- Excessive vibration and wear
- Thread damage or cracking
- Loss of hydraulic efficiency
A proper fitting ensures leak-free performance, safety, and longer equipment life.
Final Thoughts
Hydraulic fittings come in many types and thread standards, but understanding how sizes correlate across JIC, NPT, ORFS, BSP, and Metric standards helps simplify maintenance and replacement.
Always measure carefully and refer to a verified hydraulic fitting size chart like the one above to ensure compatibility and performance in your hydraulic system.
