How to Check if a Light Bulb Is Burned Out

Swap the bulb into a working lamp first

The fastest way to confirm whether a bulb has burned out is to move it into another light fixture you know works. You do not need special tools or electrical skills. A fixture swap gives you a clear answer in less than two minutes while keeping things safe.

Turn off the fixture switch and unplug the lamp cord from the wall outlet. If the bulb was on recently, give the glass five minutes to cool down to room temperature so you do not burn your fingers. Once cool, gently turn the bulb counterclockwise to remove it from the socket.

1. Find a second lamp in your home that is currently plugged in and lights up normally.
2. Turn off the working lamp and disconnect its cord before touching the socket.
3. Check that the base sizes match. Standard household table lamps use a medium screw base (labeled E26). Smaller accent lamps and chandeliers use a candelabra or small screw base (labeled E12).
4. Gently screw the suspect bulb into the working fixture until snug. Do not overtighten it.
5. Plug the lamp cord back into the wall outlet and switch it on.

If the bulb illuminates, the bulb is fine. That means the issue is in your original lamp, a faulty switch, or the wall outlet. If the bulb stays dark in the second lamp, the bulb has failed and needs replacement.

Multi-setting table lamps need extra attention. Lamps with three brightness settings use three-way light bulbs with two separate internal filaments (such as 30, 70, and 100-watt equivalent ratings). If one filament snaps while the other survives, the bulb might light up on low or medium but go dark on high.

Pin-based bulbs also require matching sockets. Directional track heads often use a twist-and-lock two-prong base (GU10) or a two-pin push-in base (GU5.3). Never force these into standard screw sockets; verify them only by swapping them into a matching fixture.

Look for broken wire filaments or dark glass

A quick physical check can tell you immediately if a traditional bulb has burned out. This visual inspection works best on incandescent bulbs, vintage clear bulbs, and halogen capsules where internal parts are visible through clear glass.

In these bulbs, light comes from a filament, which is the thin wire inside that glows when electrical current passes through it. Over time, heat weakens this wire until it snaps, breaking the circuit.

• A broken or detached wire: Hold the clear bulb toward a bright window. Look at the upright metal support arms inside the glass. If the thin wire stretching between those arms has snapped or dangles loosely, the bulb is burned out.
• Dark or smoky glass: When a tungsten wire breaks under high heat, vaporized metal particles coat the glass. If the glass looks smoky, mirrored, or stained with black soot, the bulb has burned out.
• A rattling sound: Gently tilt the bulb near your ear. If the wire broke into small pieces, you might hear a faint tinkling sound. Do not shake the bulb hard, which could break an intact filament.
• Cloudy white powder: Halogen bulbs rely on pressurized gas inside a quartz capsule. If the quartz cracks, air enters and leaves a white powdery film. When installing a replacement, remember how to safely change a halogen bulb without touching the quartz glass with bare fingers, since skin oils cause hot spots that crack the glass.

Visual checks have limits. Teardrop bulbs (standard A19 or A21 shapes), round vanity globe bulbs (G25), and recessed flood bulbs (BR30) usually have frosted white coatings or plastic domes. Because you cannot see inside, you must verify them using a working fixture or a meter.

Use a meter to verify an unbroken electrical path

When you cannot see inside a bulb, a digital multimeter is the most reliable tool to verify it. A multimeter is a small handheld electrical meter that measures electrical values. Here, you use it to check continuity, which means an unbroken electrical path that allows current to travel through a circuit.

Every functioning screw base bulb relies on an unbroken path. Electricity enters through the small metal contact point at the bottom center of the base, flows through the lighting element, and exits through the threaded metal side. If that path is broken, current cannot flow. A continuity check verifies whether that internal path remains whole.

1. Turn your digital meter to the continuity setting, marked by a sound wave or diode icon. If your meter lacks a sound function, set the dial to the lowest resistance setting (measured in ohms, marked by the omega symbol).
2. Touch the red and black metal probe tips together. The meter should emit a steady beep, or show a reading near zero ohms, confirming the meter works.
3. Hold the dry bulb in one hand. Place one probe tip firmly against the bottom metal contact point at the center of the base, avoiding the black insulating ring.
4. Place the second probe tip against the threaded metal side of the screw base.
5. Read the result. A steady beep or low resistance reading confirms an unbroken path. If the meter stays silent or displays "OL" (open loop), the circuit is broken and the bulb is dead.

For spotlight bulbs with a twist-and-lock two-prong base (GU10) or accent bulbs with a two-pin push-in base (GU5.3), place one probe on each metal pin. A continuous beep confirms the connection between the pins is intact.

If you do not have a meter, you can verify small incandescent bulbs with a household 9-volt battery and a wire. Strip both ends of the wire. Hold one end to the battery negative terminal and touch the other end to the bulb screw threads, while touching the bulb bottom contact directly to the battery positive terminal. If the filament is intact, the bulb will glow softly. Never try this on LED bulbs, because raw direct current can ruin delicate microchips.

Modern LED bulbs fail without visible damage

Homeowners often feel puzzled when an LED bulb stops working. You can hold an LED bulb to the light, shake it, look at the plastic dome, and see no damage. There is no wire to snap, no soot, and no loose pieces inside, yet it will not turn on.

LED bulbs do not produce light with a glowing wire. They use microscopic light-emitting diodes mounted on a small board. Hidden inside the base sits an electronic driver, which is a miniature circuit board that converts 120-volt alternating current into low-voltage direct current. When an LED fails, this electronic driver almost always breaks down, not the diodes.

• Heat buildup in enclosed fixtures: Heat is the leading cause of early LED failure. In airtight ceiling globes or enclosed porch lanterns, heat cannot escape. Unless packaging marks the bulb as "enclosed fixture rated," trapped heat cooks the driver until it fails permanently.
• Dimmer switch conflicts: Older wall dimmers adjust light by cutting up the electrical wave. Putting a non-dimmable LED bulb on an older dimmer stresses the driver. The bulb will buzz, flicker, or burn out within weeks. Confirm packaging says "dimmable" before installing bulbs on dimmers.
• Moisture exposure: Standard indoor bulbs installed in humid bathrooms or outdoor fixtures suffer from internal corrosion. Check packaging for a "damp location rated" mark for bathrooms and covered porches, or "wet location rated" for exposed outdoor fixtures.

Driver failure also explains why a meter continuity check is not always definitive on LED bulbs. The internal driver contains diodes and capacitors that block low-voltage meter currents in one direction. A healthy LED bulb might produce no sound on a continuity check because the meter voltage is too weak to activate the driver. For LED bulbs, swapping the bulb into a working fixture is the most dependable home check.

Fluorescent tubes have similar electronic limits. They depend on internal gases and ballasts to glow; see how long fluorescent bulbs last to understand why darkened tube ends and humming ballasts signal that a tube is ready for replacement.

Check the socket tab when a working bulb stays dark

If your bulb worked in a second lamp, your bulb is in good shape. That leaves you with a dark fixture. Many people fear their wiring has failed or the fixture is dangerous. Usually, the culprit is simply a flattened socket tab.

Inside every standard screw socket sits a small brass contact. This socket tab is the small metal contact at the bottom of the socket that delivers power to the center of the bulb base. Screwing bulbs in too hard flattens this tab against the bottom insulator.

Modern LED bulbs often have slightly flatter bottom contact points than older incandescent bulbs. When you screw a new bulb into a socket with a flattened tab, the threads stop turning before the base touches the tab. Without that physical contact, no circuit forms and the bulb stays dark.

You can gently adjust a flattened socket tab in a few minutes:

1. Cut all electrical power first. Unplug a portable lamp from the wall. For ceiling lights or sconces, switch off the breaker at your main panel and flip the wall switch to verify no power reaches the fixture.
2. Shine a flashlight into the empty socket and locate the small brass tongue at the center of the socket floor.
3. Use a wooden craft stick, a stiff plastic tool, or a small insulated flathead screwdriver to slide under the edge of the tab.
4. Gently pry the tab upward by about one-eighth of an inch (two to three millimeters). Do not yank it repeatedly, as thin brass can snap.
5. Screw your bulb back into the socket until finger-snug. Do not overtighten it. Restore electrical power and turn on the switch.

If adjusting the socket tab does not solve the problem, check these common fixture issues:

• Tripped GFCI outlet: Outlets in bathrooms, kitchens, and garages are often linked to ground-fault circuit interrupters. If one trips, it shuts down fixtures down the line. Press the Reset button firmly until it clicks.
• Switched wall outlets: Many living rooms have wall outlets controlled by a wall switch near the doorway. If that wall switch is off, a lamp plugged into that outlet will not turn on.
• Tripped circuit breaker: Check your main electrical panel for a breaker handle resting in the middle position. Switch it fully off, then flip it back to on.

Know when to call a licensed electrician. If you notice a burning plastic odor, hear buzzing sounds from the switch, see scorched metal inside the socket, or the breaker trips repeatedly, turn the breaker off and call a professional.