H7 Bulbs Explained: The 477 PX26d Headlight Bulb, H7 Equivalents, and How to Fit It
An H7 bulb is the 477: a 12V 55W single-filament halogen headlight bulb on a PX26d base. 24V 70W version, H7 equivalents explained, and UK LED rules.
In this guide
An H7 bulb is a single-filament halogen headlight bulb on a PX26d base with 2 connector pins. The standard 12-volt H7 is rated 55 watts and gives about 1,500 lumens. In the UK it is sold as the 477, and some brands use 499. The 24-volt version is rated 70 watts. Each H7 gives one beam only, so a headlamp usually needs one H7 for dipped and another for main beam.
This guide explains what the H7 code means, the PX26d base, the 12V and 24V ratings and UK numbers, where H7 bulbs are used on tractors and road vehicles, what people really mean by an “H7 equivalent”, where LED H7 bulbs stand under UK rules, and how to fit one.
What Is an H7 Bulb?
An H7 is a halogen filament lamp category defined in UNECE Regulation 37. It has one filament inside a quartz glass capsule filled with halogen gas, and it has no shield cap. The headlamp’s reflector or projector lens, not the bulb, shapes the light into either a dipped beam with a sharp cut-off or a long main beam.
Because the bulb only does one job, makers can tune the optics around a single filament in a fixed position. That gives a precise beam, which is why the H7 spread through car headlamps from the 1990s onwards and appears in many newer tractor, telehandler and loader headlamps.
| Specification | H7 12V | H7 24V |
|---|---|---|
| UK number | 477 (also sold as 499) | 474 (Ring numbering) |
| Wattage | 55W | 70W |
| Light output | 1,500 lumens | 1,750 lumens |
| Base | PX26d | PX26d |
| Filaments | 1 | 1 |
| Connector pins | 2 | 2 |
The light output figures are the reference values in Regulation 37, which allows a tolerance of plus or minus 10 percent. Some makers quote a lower figure for their standard H7 (one major maker lists 1,350 lumens), so compare bulbs within the same brand rather than across brands.
The PX26d Base
The PX26d is a prefocus base with a flat metal flange and a locating tab, so the bulb only seats in the headlamp one way. That fixes the filament at the exact point the optics were designed around. A wire spring clip or a retaining ring holds the flange against the headlamp, and the 2 flat pins on the back take a 2-way connector: one feed and one earth.
The PX26d base is not shared with the other common headlamp bulbs. The H4 uses a P43t base with 3 pins, the H1 uses a P14.5s base and the H11 uses a PGJ19-2 base with an L-shaped plastic body. None of them fits an H7 headlamp correctly.
477, 499 and 474: The UK Numbers
- 477 is the most widely used UK trade number for the 12V 55W H7, sometimes with a prefix such as R477.
- 499 is used by some brands for the same 12V 55W H7 bulb. A 477 and a 499 marked H7 12V 55W are the same bulb. Ring uses R499 for a different, off-road H1 bulb, so check for the H7 marking.
- 474 is Ring’s number for the 24V 70W H7, used on lorries, plant and 24V tractors. Other brands may simply label it H7 24V.
Because the numbers vary by brand, the safest check is the printing on the base: H7, the voltage and the wattage. A 12V bulb on a 24V machine blows almost at once, and a 24V bulb on a 12V machine gives a weak yellow light. See 12V vs 24V lighting systems if you are not sure which you have.
What H7 Bulbs Are Used For
- Dipped beam headlamps in twin-bulb headlamps, often behind a projector lens.
- Main beam headlamps, either in the same housing as the dipped beam or as a separate lamp.
- Tractor, telehandler and loader headlamps on many newer machines that use separate dipped and main beam units.
- Front fog lamps and some auxiliary and work lamps built around an H7.
Check the old bulb rather than going by model, because the same machine range can change headlamp type during production. The comparison with the twin-filament bulb used in single-bulb headlamps is in H4 vs H7 bulbs, and other halogen types are set out in halogen headlamp bulb types.
What Is an H7 Equivalent?
There is no other bulb type that is a direct equivalent of an H7. The only correct replacement for an H7 is another H7 of the right voltage. When someone asks for an “H7 equivalent”, they usually mean one of 4 things, and each has a different answer.
A different brand or part number
Any bulb marked H7 with an E mark and the right voltage and wattage is an equivalent, whatever the brand. The 477 and 499 numbers are the same bulb. This is the normal answer.
A brighter or longer-lasting H7
Uprated H7 bulbs sold as +50%, +100% or +150% are still H7 55W bulbs and are road legal when E-marked. The percentage refers to the light at a point in the beam, not total output, and these bulbs often have a shorter life. Long-life H7 bulbs trade some brightness for more hours. Both are true H7 equivalents. For longer intervals between changes, see our lifetime halogen bulbs.
A different bulb code that looks similar
H1, H3, H11 and other single-filament halogens are not H7 equivalents. They have different bases, filament positions and connectors, so they will not seat correctly and cannot give a correct beam even if adapted. High-wattage “H7” bulbs of 80 or 100 watts are sold for off-road use only and are not approved for the road.
An LED “H7 equivalent”
LED bulbs with an H7 base are often sold as H7 equivalents. On vehicles that take an MOT, fitting one in a halogen headlamp is a fail (see the next section). An LED H7 is not an equivalent for road use in the UK.
Are LED H7 Bulbs Legal in the UK?
The DVSA MOT inspection manual for cars and light vans says existing halogen headlamp units on vehicles first used on or after 1 April 1986 must not be converted to HID or LED bulbs. If they have been, the tester must fail the headlamp as a major defect for “light source and lamp not compatible”. Complete replacement headlamp units built with LED light sources are not affected. From 14 October 2026 (a DVSA change to the MOT inspection manual) testers must also accept ECE-approved LED replacement (LEDr) bulbs that have their approval sticker fixed to the vehicle.
Some LED H7 bulbs have national approval in other European countries for listed vehicles, but that approval does not apply in the UK. In 2025 the first LED replacement bulb approved under Regulation 37 was launched in the H11 category, and from 14 October 2026 the MOT accepts approved LEDr bulbs with their sticker. At the time of writing no LEDr bulb is approved for H7. Treat any “road legal LED H7” claim with caution in the UK.
Most tractors are exempt from the MOT, but the lighting regulations still apply on the road, and an LED bulb in a reflector built for a filament can throw light above the cut-off. The compliant route to LED headlights is a complete E-marked LED headlamp. The options are explained in LED headlamp conversions, and you can browse tractor headlights.
How to Fit an H7 Bulb
- Switch off the lights and ignition, and turn off the battery isolator on a tractor.
- Reach the back of the headlamp. On many tractors this means lifting the bonnet or removing a grille or headlamp cover.
- Pull off the 2-pin connector and remove the dust cover.
- Release the spring clip or turn the retaining ring, and lift out the old bulb, noting which way the locating tab sits.
- Check the code and voltage on the old bulb: H7 12V 55W or H7 24V 70W.
- Hold the new bulb by its metal flange or plastic base only. Do not touch the glass, because skin oils create hot spots that shorten its life.
- Seat the bulb with the tab in the slot so the flange sits flat, then refit the clip.
- Refit the dust cover so it seals all the way round, then the connector.
- Test the beam. If both headlamps use H7 for dipped beam, replace both bulbs together so the colour and brightness match.
If you do touch the glass, wipe it with isopropyl alcohol on a lint-free cloth before switching on. Shop standard halogen bulbs for 12V and 24V H7 replacements. If your headlamp has one bulb for both beams, you need the twin-filament bulb in H4 bulbs explained.
Frequently asked questions
Is a 477 bulb the same as an H7?
Yes. H7 is the ECE category and 477 is the most common UK trade number for the 12V 55W version. Some brands use 499 for the same bulb.
What is the equivalent of an H7 bulb?
Only another H7. Any E-marked H7 of the same voltage from any brand is an equivalent, including uprated and long-life versions. Other codes such as H1 or H11 do not fit, and LED H7 bulbs are not road legal in halogen headlamps on MOT-tested vehicles.
Is an H7 12V 55W the standard bulb?
Yes. 55 watts is the standard rating for a 12V H7. The 24V version is 70 watts. Bulbs rated 80 or 100 watts are off-road only.
Can I use an H4 instead of an H7?
No. The H4 has 2 filaments, a P43t base and a 3-pin connector, so it does not fit an H7 headlamp.
Why do my H7 bulbs keep blowing?
Common causes are touching the glass during fitting, water getting past a split dust cover, a loose connector, vibration and high charging voltage. Check those before fitting another bulb.