Dash Size Chart (Printable)
Dash numbers -4 through -32 mapped to fractional inch and millimeter sizes for SAE/JIC tube and hose fittings. Dash sizing is not NPT sizing — pipe threads follow their own chart.
Dash, inch and mm
| Dash | Fractional inch | mm | Typical use |
|---|---|---|---|
| -4 | 1/4 | 6.35 | Small instrument and pilot lines |
| -6 | 3/8 | 9.53 | Workhorse instrument tube size |
| -8 | 1/2 | 12.70 | Instrument and hydraulic mains |
| -10 | 5/8 | 15.88 | Medium hydraulic lines |
| -12 | 3/4 | 19.05 | Process and hydraulic distribution |
| -14 | 7/8 | 22.23 | Less common; larger instrument runs |
| -16 | 1 | 25.40 | Hydraulic supply and return lines |
| -20 | 1-1/4 | 31.75 | Larger hydraulic and process runs |
| -24 | 1-1/2 | 38.10 | Manifold and station feeds |
| -28 | 1-3/4 | 44.45 | Rare; special machinery runs |
| -32 | 2 | 50.80 | Large-bore hose and tube headers |
How to use this chart
Divide the dash number by 16 to get inches. On tube fittings the dash number corresponds to tube outside diameter; on hose ends it commonly denotes hose inside diameter. A -6 JIC fitting is made for 3/8 inch tube OD — and an NPT port marked -4 does not carry a 1/4 inch thread, so keep pipe threads on the NPT chart, not this one.
From our guide: the dash size chart explained. Copy the spec line as drawn onto theRFQ.