Specifications
| Outside diameter | 5.5 mm |
|---|---|
| Hole diameter | 2.1 mm |
| Jack pin | 2.0 mm |
| Centre pin in the hole | no |
| Barrel length | 9.5 or 14 mm |
| Standard | IEC 60130-10 type A |
| Rating (catalogue part) | PP3-002A: 6 A, 20 V DC; Switchcraft S760: 5 A, 12 V DC |
| Polarity | both exist: centre positive (Arduino), centre negative (Boss pedals) |
| Plug | PP3-002A · Switchcraft S760 |
| Jack | PJ-002A |
Lookalikes and how to tell them apart
The 5.5 × 2.5 looks identical: only the hole differs. A 2.1 plug won’t go onto a 2.5 mm pin; a 2.5 plug goes onto this jack’s 2.0 mm pin but wobbles and loses contact.
| Size | Centre pin | Standard |
|---|---|---|
| 5.5 × 2.1 mm | no | IEC 60130-10 type A |
| 5.5 × 2.5 mm | no | IEC 60130-10 type A |
| 5.5 × 1.7 mm | no | de facto size |
| 5.0 × 2.1 mm | no | de facto size |
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.
A 5.5 × 2.5 mm plug goes onto a jack with a 2.0 mm pin but sits loose and can lose contact; a 5.5 × 2.1 mm plug won’t go onto a 2.5 mm pin. Check the polarity symbol on the adapter too.
Guitar pedals (Boss and many others) use 9 V, centre negative, on a 5.5 × 2.1 plug: an Arduino or LED adapter with the same plug is usually centre positive.
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.
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 × 2.5 mm 5.5 × 3.0 mm 5.5 × 3.3 mm 6.3 × 3.0 mm 6.5 × 4.4 mm 7.4 × 5.0 mm 7.9 × 5.5 mm
All DC plug sizes, with a chart →
Frequently asked questions
What jack does a 5.5 × 2.1 mm plug need?
A jack for 5.5 × 2.1 mm plugs, with a 2.0 mm pin, such as the PJ-002A: makers sell plug and jack as a matching pair.
Does a 5.5 × 2.1 mm plug fit a 5.5 × 2.5 mm jack?
No: its 2.1 mm hole doesn’t go over the thicker pin of a 5.5 × 2.5 mm jack.
Does a 5.5 × 2.1 mm plug fit a 5.5 × 1.7 mm jack?
It goes in, but loosely: the pin of a 5.5 × 1.7 mm jack is thinner than its 2.1 mm hole, so the contact comes and goes when the cable moves.
Is 5.5 × 2.1 mm a standard size?
Yes: IEC 60130-10 type A.
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.