Projector Bulb: What It Is, What It Costs, and How to Pick the Right One
A projector bulb is a high-pressure mercury arc lamp - usually a Philips UHP burner or an equivalent - mounted in a dichroic glass reflector and, in most cases, enclosed in a moulded plastic cage that fits one specific projector chassis. It is not an ordinary light bulb. It runs at extreme internal pressure and temperature, it is matched electrically to the projector's ballast, and it is identified by the projector model it fits rather than by wattage.
What is actually inside a projector bulb
Three components, and understanding them explains almost everything about price and behaviour.
- The burner - a small quartz envelope containing mercury and two electrodes, operating at very high pressure when hot. The arc between the electrodes is the light source, and it is physically tiny, which is what lets the optics produce a sharp image.
- The reflector - a precisely shaped dichroic glass mirror that collects light from the arc and directs it into the projector's optical path. Its geometry is matched to the specific projector, which is why reflectors are not interchangeable.
- The cage or housing - moulded plastic that holds the assembly, provides the electrical connector, and locates the whole thing accurately in the lamp bay.
The burner alone is a commodity made by a handful of manufacturers. The reflector geometry and the cage are what make a lamp specific to your projector.
Why it is not a light bulb
Several practical differences follow from the construction:
- It needs a ballast - the projector contains electronics that strike and regulate the arc. You cannot run one from mains directly.
- Wattage is not a selection criterion - two 230W lamps from different projectors are not interchangeable. Fit is determined by reflector and cage, not power.
- It contains mercury - which is why disposal is regulated. See lamp recycling and mercury disposal.
- It dims rather than fails - output falls gradually across life, often by half before anything looks obviously wrong. See how long projector lamps last.
- Skin oil damages it - touching the quartz leaves residue that creates a hot spot and can cause early failure. Handle by the cage.
Bulb, lamp or module?
The terms are used loosely and it causes real ordering mistakes.
- Bare bulb or bare lamp - the burner and reflector only, no plastic cage. Cheaper, but you must transfer it into your existing cage.
- Lamp with module, or full assembly - burner, reflector and cage together, ready to drop in. More expensive, far simpler.
For most buyers the module is the right choice. Transferring a bare burner means handling the quartz, aligning it correctly in the cage, and getting the reflector seated square - all of which are achievable but all of which can go wrong. Our guide to re-housing a bare burner safely covers the procedure if you want to try. The terminology is covered in lamp vs bulb vs module.
What drives the price
Four things:
- OEM versus compatible - an OEM lamp uses the original burner and reflector in the original cage. A compatible uses an equivalent burner in a third-party cage. See OEM vs compatible.
- Bare versus module - the cage adds cost
- How common the model is - a lamp for a popular projector costs less than one for a low-volume or discontinued model
- Market age - lamps for current projectors are cheaper than lamps for long-discontinued ones, where supply is thin
Current US pricing across the range is in projector lamp prices in 2026, and replacement cost versus replacing the projector covers when a new lamp stops making sense.
Getting the right part
Order by projector model, never by appearance. Visually identical cages differ in bracket positions and connector type.
- Find the projector model number on the base or rear label
- Look up the lamp part number - see finding your part number
- Cross-check equivalents if you have a part number but no model - see the cross-reference guide
- Decide OEM or compatible, and bare or module
Browse by brand: BenQ, Optoma, ViewSonic, Acer, Eiki, InFocus, Sanyo, Dukane, Boxlight and Hitachi.
Before you buy
A dim image is not always the lamp. Check the air filter, eco mode and lens cleanliness first - see diagnosing a dim image. And if a new lamp does not fix it, our guide to a new lamp not working covers the nine usual causes.
Frequently asked questions
What is a projector bulb?
A high-pressure mercury arc lamp, usually a Philips UHP burner or equivalent, mounted in a dichroic reflector and typically enclosed in a moulded cage that fits one specific projector. It is not an ordinary light bulb and cannot be run without the projector's ballast.
How much does a projector bulb cost?
It varies with whether you buy OEM or compatible, bare bulb or full module, and how common your projector model is. Lamps for popular current models cost considerably less than those for discontinued low-volume projectors.
Can I use any bulb with the same wattage?
No. Wattage does not determine fit. The reflector geometry and the cage are matched to one projector chassis, so two 230W lamps from different projectors are not interchangeable.
What is the difference between a bare bulb and a lamp module?
A bare bulb is the burner and reflector without the plastic housing, and you transfer it into your existing cage. A module is the complete assembly ready to install. Modules cost more and are much simpler to fit.
Why do projector bulbs cost so much?
They are precision optical assemblies, not light bulbs. The reflector is a shaped dichroic mirror matched to the projector's optics, the burner runs at extreme pressure and temperature, and production volumes are small compared with general lighting.
Can I touch the glass on a projector bulb?
Avoid it. Skin oil on the quartz envelope creates a hot spot when the lamp runs and can cause premature failure. Handle the assembly by its plastic cage.
Finding your lamp
Lamps Authority stocks projector lamps for thousands of models across more than forty brands, in both OEM and compatible options. Send us your projector model number and we will identify the correct part.