External Torx Size Chart
Quick answer: external Torx bolts use E-size sockets such as E4, E8, E10, and E12. The E number is not the same as an internal T-bit size. For example, E8 is commonly listed around 7.4 mm point-to-point and is often associated with M6/M7 external Torx fasteners.
External Torx Socket Size Chart
| E socket size | Point-to-point approx. | Point-to-point inches | Common fastener match |
|---|---|---|---|
| E4 | 3.8 mm | 0.150 in | #6 / M3 range |
| E5 | 4.7 mm | 0.185 in | #8 / M4 range |
| E6 | 5.6 mm | 0.225 in | #10 / M5 range |
| E7 | 6.1 mm | 0.241 in | Small automotive fastener |
| E8 | 7.4 mm | 0.292 in | 1/4 in / M6-M7 range |
| E10 | 9.3 mm | 0.367 in | 5/16 in / M8 range |
| E12 | 11.1 mm | 0.436 in | 3/8 in / M10-M11 range |
| E14 | 12.8 mm | 0.503 in | 7/16 in / M12 range |
| E16 | 14.7 mm | 0.576 in | 1/2 in range |
| E18 | 16.6 mm | 0.652 in | 9/16 in / M14 range |
| E20 | 18.4 mm | 0.722 in | 5/8 in / M16 range |
| E24 | 22.1 mm | 0.870 in | 3/4 in / M18-M20 range |
External Torx Fit Tips
- Use an E socket on external Torx heads; do not use a standard 6-point socket if the fit is loose.
- Clean rust and paint from the bolt head before judging size.
- External E sizes do not directly match internal T-bit sizes.
- Use impact-rated E sockets with impact tools.
Related references: Allen wrench size chart, socket sizes in order, and bolt spanner size chart.
Source Notes
External Torx dimensions were checked against E-socket references including Newman Tools Torx dimensional specifications, Tien-I’s star socket chart guidance, and tool manufacturer socket listings. Fit the socket to the actual fastener before applying torque.
