Specifications
| Outside diameter | 6.5 mm |
|---|---|
| Hole diameter | 4.3–4.4 mm |
| Centre pin in the hole | yes, 1.4 mm |
| Barrel length | 9.5–16 mm |
| Standard | EIAJ class 5, 13.5–18 V |
| Rating (catalogue part) | Lumberg 1636 05: 2 A, 18 V DC |
| Polarity | not set by the size: read the symbol |
| Plug | Lumberg 1636 05 |
Lookalikes and how to tell them apart
The 6.3 × 3.0 is slightly thinner and has no pin; the laptop 7.4 × 5.0 is bigger.
| Size | Centre pin | Standard |
|---|---|---|
| 6.5 × 4.4 mm | yes, 1.4 mm | EIAJ class 5, 13.5–18 V |
| 6.3 × 3.0 mm | no | de facto size |
| 7.4 × 5.0 mm | yes | de facto size |
| 5.5 × 3.3 mm | yes, 1.0 mm | EIAJ class 4, 10.5–13.5 V |
Before you plug it in
Measure with a caliper: the metal sleeve gives the outside diameter. For the hole, use drill bits as gauges: the largest one that slides in gives the size. If there is a pin in the middle, a bit won’t go in: use the caliper’s inside jaws.
The size says nothing about polarity: look for the symbol (a dot inside a C, with + and −) on the device and on the adapter. Centre positive is the most common.
In the EIAJ standard each voltage band has its own size, larger for higher voltages, so a plug won’t go into a jack for a lower band. A smaller plug can still enter a larger jack (class 2 into class 3), and outside Japan the bands aren’t always kept: read the label.
Open the connector identifier →Not sure it is this size? Enter the outside and hole diameters: the identifier compares 22 DC plug sizes.
Other DC plug sizes
2.0 × 0.6 mm 2.35 × 0.7 mm 2.5 × 0.7 mm 3.0 × 1.1 mm 3.5 × 1.1 mm 3.5 × 1.35 mm 4.0 × 1.35 mm 4.0 × 1.7 mm 4.5 × 3.0 mm 4.75 × 1.7 mm 4.8 × 1.7 mm 5.5 × 1.7 mm 5.5 × 2.1 mm 5.5 × 2.5 mm 5.5 × 3.0 mm 5.5 × 3.3 mm 6.3 × 3.0 mm 7.4 × 5.0 mm 7.9 × 5.5 mm
All DC plug sizes, with a chart →
Frequently asked questions
Is 6.5 × 4.4 mm a standard size?
Yes: EIAJ class 5, 13.5–18 V.
Sizes and ratings from the makers’ catalogues (Same Sky, Lumberg, Switchcraft) and the EIAJ and IEC summaries. A plug’s rating is a maximum: the adapter’s label says what it actually supplies.