Bulb shapes and sizes

Light bulb shape chart

The letters name the envelope family. In many U.S. codes, the number gives nominal maximum diameter in eighths of an inch. Read the base, voltage, and exact dimensions elsewhere on the lamp or specification sheet.

Ashape family+19nineteen eighths of an inch=2⅜ innominal maximum diameter

Silhouettes are representative family profiles, not scaled manufacturer dimension drawings. The arrow compares nominal maximum diameter; overall length, shoulder, neck, and optics vary by product.

General A shapes

4 reference profiles

1.875 in (48 mm)

A15

compact A-shape bulb

ceiling fans · appliances

2.375 in (60 mm)

A19

standard A-shape bulb

table lamps · floor lamps

2.625 in (67 mm)

A21

large A-shape bulb

high-lumen lamps · garage fixtures

3.125 in (79 mm)

A25

extra-large A-shape bulb

high-output fixtures · commercial pendants

Decorative and candle shapes

5 reference profiles

1.25 in (32 mm)

B10

blunt-tip decorative bulb

chandeliers · wall sconces

1.375 in (35 mm)

B11

large blunt-tip decorative bulb

chandeliers · pendants

0.875 in (22 mm)

C7

small cone-shaped bulb

night lights · holiday strings

1.125 in (29 mm)

C9

cone-shaped decorative bulb

holiday strings · outline lighting

1.25 in (32 mm)

CA10

bent-tip candle bulb

chandeliers · decorative sconces

Globe shapes

4 reference profiles

2.063 in (52 mm)

G16.5

small globe bulb

vanity lights · decorative fixtures

3.125 in (79 mm)

G25

medium globe bulb

bathroom vanities · makeup mirrors

3.75 in (95 mm)

G30

large globe bulb

vanity bars · open pendants

G40

extra-large globe bulb

large pendants · decorative strings

Reflector shapes

12 reference profiles

BR20

small bulged-reflector bulb

small recessed cans · track lights

3.75 in (95 mm)

BR30

bulged-reflector flood bulb

recessed cans · track lights

BR40

large bulged-reflector flood bulb

large recessed cans · high-ceiling flood lighting

PAR16

small PAR reflector bulb

track lights · small spotlights

PAR20

PAR reflector bulb

track lights · small recessed cans

3.75 in (95 mm)

PAR30

medium PAR reflector bulb

recessed cans · track lights

4.75 in (121 mm)

PAR38

large PAR reflector bulb

outdoor floods · security lights

1.375 in (35 mm)

MR11

small multifaceted-reflector bulb

display lights · landscape lights

MR16

multifaceted-reflector bulb

recessed spotlights · track lights

R20

small reflector bulb

track lights · small recessed cans

3.75 in (95 mm)

R30

medium reflector bulb

recessed cans · display lighting

R40

large reflector bulb

large recessed fixtures · heat-lamp-style housings

Tubular shapes

4 reference profiles

T4

narrow tubular bulb

cabinet lights · appliances

0.625 in (16 mm)

T5

tubular lamp

linear fixtures · cabinet lights

T8

one-inch tubular lamp

troffers · shop lights

1.25 in (32 mm)

T10

wide tubular lamp

picture lights · signs

Sign and Edison-style shapes

2 reference profiles

1.75 in (44 mm)

S14

sign bulb

patio strings · signs

2.375 in (60 mm)

ST19

straight-sided Edison-style bulb

open pendants · decorative lamps