H7 Bulb
Light Bulbs & Sockets · 7 specs
Direct Answer
The H7 Bulb (standardized under UN ECE Regulation 37 with a PX26d flanged base) is the most widely used single-filament halogen automotive headlight bulb in the world. Operating at 55W nominal at 12V (rated at 13.2V test voltage), it generates 1,500 lumens (±10%) primarily for low-beam projector and reflector headlight assemblies.
Source: UN ECE Regulation 37 (Filament lamps for use in approved lamp units) / IEC 60061-1 (7004-5) · Last reviewed Aug 28, 2026
Specs
| Standardization | UN ECE R37 Category H7 / IEC 60061-1 sheet 7004-5 / US DOT Category H7 |
| Base Socket Designation | PX26d (pre-focused metal circular mounting flange with one flat reference indexing tab) |
| Filament Type | Single axial tungsten filament (no internal shield; strictly a single-beam bulb) |
| Nominal Power & Voltage | 55 W @ 12V nominal (tested at 13.2V standard regulation voltage; draws ~4.17 A) |
| Luminous Flux Output | 1,500 lumens ± 10% (at 13.2 V) |
| Average Lifespan (B3 / Tc) | B3 (97% survival): ~330 hours | Tc (63.2% failure): ~550 hours (standard halogen) |
| Electrical Terminals | 2 spade push-on terminals (6.3 mm faston tabs spaced 14.5 mm apart) |
The Pre-Focused PX26d Flange
Because halogen optical reflectors require sub-millimeter positioning of the incandescent filament at the focal point of the parabolic mirror, the PX26d metal flange features a single flat indexing tab. The bulb can only seat in one specific rotational angle, ensuring the tungsten coil is precisely centered in the optical beam axis.