What Is an H7 Bulb? | Headlight Specs and Fitment Guide

If you’ve popped your hood and found “H7” stamped on a bulb base, you’re looking at a 12-volt, 55-watt halogen lamp producing roughly 1,500 lumens. It’s a standard size in European cars and some U.S. models, and unlike the H4, it’s strictly a one-job bulb. The simple question — what fits, what doesn’t, and what that number on the package actually means — is what this guide answers in about three minutes of reading.

Standard H7 Bulb Specifications

The H7’s design is standardized across manufacturers, so the core specs stay the same whether you grab an OSRAM or a SYLVANIA unit. The base is PX26d, voltage is 12 V, power is 55 W, and the nominal light output sits around 1,500 lumens at roughly 3,200 K color temperature. OSRAM’s official ORIGINAL LINE entry lists a 59.0 mm length, 12.0 mm diameter, and a lifespan range of 330 hours (B3) to 550 hours (Tc). SYLVANIA’s Basic H7 datasheet reports 56.00 W actual power at 12.80 VDC, 1,500 lumens, and a 270-hour rated life. A 24 V / 70 W heavy-duty H7 variant exists for trucks and commercial vehicles, but the 12 V / 55 W version is what you’ll find in nearly every passenger car application.

All genuine H7 bulbs share the PX26d base — two flat opposing tabs — and a single filament set in a precise position. That filament placement is what makes the beam pattern correct in a given housing.

Where an H7 Bulb Is Used

H7 bulbs serve low-beam, high-beam, or fog-light duties depending entirely on the headlamp assembly, not on the bulb itself. A single H7 does one job at a time. Many European sedans use H7 for low beams, while some BMW and Audi models run H7 in both the low- and high-beam positions. Japanese-market vehicles and some U.S. models also spec H7 in specific housings. The vehicle’s owner manual or the marking on the old bulb casing will tell you exactly which position it serves. Unlike the H4, which packs high and low filaments in one envelope, the H7 is always a single-beam bulb — swapping it from low to high requires a different housing or a second bulb socket.

How to Choose the Right H7 Bulb

Matching the bulb to your car is a three-check process. First, verify the base is PX26d — that’s the H7’s unique two-tab locking pattern. Second, confirm the voltage and wattage the vehicle expects; the standard is 12 V / 55 W, but some heavy-duty or commercial applications need the 24 V / 70 W variant. Third, identify which beam function the bulb will serve. Buying an “H7” LED or HID conversion kit is becoming common, but those products depart from the halogen spec and require compatible housing, correct polarity, and adequate heat management. A retailer may list an H7 halogen bulb as DOT-approved, but that certification does not transfer to aftermarket LED replacements. For the safest single purchase, buy the exact type — halogen, voltage, wattage — that matches the car’s original equipment. Our roundup of the best white H7 halogen bulbs covers options that maintain proper beam pattern and street legality.

Common H7 Mistakes to Avoid

The top error is confusing H7 with H11 or H4 — they look different at the base and their filament positions are not interchangeable in the same housing. A second common misstep is buying on lumen claims alone. Standard halogen H7 delivers about 1,500 lm. The third mistake is assuming all H7 bulbs fit every car; physical fit, base orientation, and housing depth vary. Use the PX26d identifier and the car’s manual, not the “universal” label on the package.

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