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Engineering Reference

How to Read Bulb Voltage and Wattage

Understand voltage and wattage markings on specialty bulbs and how to use them for safer B2B replacement sourcing.

Direct answer

Voltage tells you the circuit the bulb is designed for, while wattage tells you power consumption and helps estimate heat and brightness. Both values should be matched to the fixture or equipment requirement before replacement.

Applicable to: For B2B replacement, sourcing and custom lighting projects. Confirm final fit, performance and commercial terms against the exact product specification.

Last reviewed 2026-07-19Technical review: AOTENG Lighting technical sourcing teamEdited by AOTENG Lighting editorial team

Direct answer

Voltage tells you the circuit the bulb is designed for, while wattage tells you power consumption and helps estimate heat and brightness. Both values should be matched to the fixture or equipment requirement before replacement.

Comparison table

MarkingMeaningBuyer action
12VDesigned for a 12 volt circuitMatch with 12V equipment or confirm by RFQ
24VDesigned for a 24 volt circuitCommon in many equipment and vehicle systems
5WConsumes about 5 watts under rated conditionsCheck heat, brightness and fixture rating
V rangeMay indicate a range or multiple available variantsConfirm exact required version before order

How to identify

Look for voltage and wattage printed on glass, base or packaging.

Do not confuse volts with watts.

When several numbers appear in the product name, confirm which one is voltage and which one is wattage.

Check whether the replacement is intended for AC, DC or a specific driver.

Buyer checks

Send the original marking exactly as printed.

Provide the target equipment voltage.

Confirm acceptable wattage or brightness target.

Confirm by RFQ if the marking is incomplete or includes multiple variants.

Confirm by RFQ

AOTENG can quote by voltage and wattage, but the buyer should confirm equipment rating, fixture heat limits and approval requirements.

Common mistakes

Reading 12V3W as a model number instead of voltage and wattage.

Assuming the same base means the same wattage is acceptable.

Selecting a brighter lamp without checking heat limits.

FAQ

Which is more important, voltage or wattage?

Both matter. Voltage must match the circuit, and wattage affects load, heat and brightness.

Can I choose a higher wattage bulb?

Do not assume so. Higher wattage can create more heat or exceed fixture limits.

What if the old marking is unreadable?

Send photos, dimensions and equipment details, then Confirm by RFQ.

Sources and limits

Related application routes