A familiar wattage is not enough to choose a replacement bulb. Start with the fixture's requirements, then compare brightness and the appearance of the light. Energy use is a separate specification.
Match the physical and electrical requirements first
Check the base type, shape, size, and the fixture's permitted use. If the fixture is enclosed or uses a dimmer, the bulb must be suitable for that arrangement. Follow manufacturer instructions and do not exceed the fixture's rating.
Switch off power and let the bulb cool before handling it. This guide is for choosing a compatible replacement, not repairing a fixture or altering wiring.
Compare the experience you want
Lumens describe light output. Color temperature, expressed in kelvins, describes the light's warm or cool appearance. A brighter bulb is not necessarily a cooler-looking bulb; the two properties can be selected separately.
For a reading lamp, consider the amount and direction of light at the task. For several bulbs in one room, matching appearance may matter. Keep the packaging from a bulb you like so that future replacements can be compared accurately.
Read energy estimates with their assumptions
An estimated yearly energy cost depends on assumed hours of use and electricity price. Your actual use may differ. Compare the wattage and lumen output under similar conditions rather than treating the printed cost as a guaranteed bill.
Before buying a multipack, consider testing one compatible bulb in the intended location if returns and packaging terms allow it. A specification sheet narrows the choice, but glare, shade design, and room surfaces affect the result you see. Choose the bulb that fits the fixture and the task, not just the largest equivalent-wattage claim.
Sources
- US Department of Energy: Consumer guide to lighting
Lumens, color temperature, and energy use are separate bulb specifications.
- US EIA: Measuring electricity
Watts measure power and watt-hours measure energy over time.