Light Bulb Shape & Size Chart
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Selection Methodology: Picks come from verified manufacturer data sheets, certification databases (DesignLights Consortium QPL for commercial fixtures, California Title 24 JA8, FTC Lighting Facts, and EPA ENERGY STAR for recessed downlights), and owner failure-rate analysis. We do not run hands-on lab tests.
Every US light bulb shape code pairs a letter for the glass profile with a number giving its widest diameter in eighths of an inch. Divide the number by 8 to get exact width in inches (for example, A19 = 19 ÷ 8 = 2.375 inches wide).
Interactive Bulb Shape Code Decoder
Visual Profiles of Common LED Bulb Shapes
Compare the silhouette before buying. Omnidirectional bulbs (A19, A21, G25) spread light all around a shade or globe, whereas directional reflectors (BR30, PAR38, GU10/MR16) concentrate all lumens forward into a controlled cone.
A19 Standard
2.375 in wide · ~4.4 in tall. Lamps, ceiling domes, sconces.
A21 High-Output
2.625 in wide · ~5.1 in tall. 100W to 150W utility & floor lamps.
BR30 Bulged Reflector
3.75 in wide · 100°+ soft flood. 5-in and 6-in indoor recessed cans.
PAR38 Parabolic Flood
4.75 in wide · 25° to 40° beam. Wet-rated exterior flood holders.
MR16 / PAR16 Spot
2.0 in wide · 15° to 40° beam. Track heads, art spots, range hoods.
G25 Vanity Globe
3.125 in spherical globe. Exposed bathroom mirror bars & pendants.
T8 Linear Tube
1.0 in wide · 48 in long. Office troffers and garage shop fixtures.
Corn Retrofit (Type B)
360° diode array for E26/E39 post tops and enclosed commercial cans.
Household, Decorative & Globe Shape Size Chart
Verify both diameter and Maximum Overall Length (MOL) whenever replacing bulbs inside enclosed ceiling domes, ceiling fan globes, or tight lamp harps.
| Shape Code | Size (Width × Height) | Usual Base | Best Fixtures |
|---|---|---|---|
| A15 Small Pear | 1.88 × 3.4 in (48 mm) | E26, E17, E12 | Refrigerators, range hoods, ceiling fan globes (15W guide) |
| A19 Standard Pear | 2.38 × 4.3 in (60 mm) | E26, GU24 | Table lamps, bedrooms, hallways (60W & 75W guides) |
| A21 Large Pear | 2.63 × 5.1 in (67 mm) | E26 | 100W to 200W floor lamps, garages (100W & 150W guides) |
| ST19 (ST64) Vintage Edison | 2.38 × 5.4 in (60–64 mm) | E26 | Exposed-socket dining pendants, industrial wall sconces |
| B10 / B11 Torpedo Candle | 1.25–1.38 × 3.7 in | E12, E26 | Dining chandeliers, wall sconces, foyer lanterns (25W guide) |
| CA10 Flame-Tip Candle | 1.25 × 4.1 in (32 mm) | E12 | Open-arm traditional chandeliers without fabric shades |
| C7 / C9 Holiday Cone | 0.88–1.13 × 2.1–2.9 in | E12 (C7), E17 (C9) | Nightlights and commercial holiday roofline strings |
| G16.5 Mini Globe | 2.06 × 3.0 in (52 mm) | E12, E26 | Compact vanity sconces, makeup mirrors, chandeliers |
| G25 (G80) Vanity Globe | 3.13 × 4.4 in (80 mm) | E26 | Exposed bathroom vanity bars and mirror lights |
| G40 (G125) Statement Globe | 5.00 × 6.7 in (125 mm) | E26 | Single-cord statement pendants (patio strings also use mini 1.5-in G40 globes) |
Directional Reflector & Floodlight Shape Chart (BR, PAR, MR)
Recessed cans, track heads, and outdoor floodlights require directional bulbs. Match both the face diameter (so the ring gap inside the ceiling trim looks clean) and the optical beam spread.
| Shape Code | Diameter & Beam | Usual Base | Can Size / Primary Application |
|---|---|---|---|
| MR11 | 1.38 in · 15°–35° | GU4 (12V) | Miniature curio cabinets, elevators, landscape step lights |
| MR16 | 2.00 in · 15°–40° | GU5.3 (12V) / GU10 | Low-voltage track, landscape spots, art walls (35W halogen) |
| PAR16 | 2.00 in · 25°–40° | GU10 / E26 (120V) | 120V kitchen track lighting, range hoods (50W halogen) |
| R20 / BR20 | 2.50 in · 90°–105° | E26 | 4-inch indoor recessed cans and compact eyeballs |
| PAR20 | 2.50 in · 25°–40° | E26 | 4-inch recessed cans over counters, art walls, damp porches |
| BR30 | 3.75 in · 100°–110° | E26 | Standard 5-inch and 6-inch indoor recessed cans (8 to 10 ft ceilings) |
| PAR30 Short Neck | 3.75 in · 25°–40° | E26 (~3.6 in tall) | Shallow track heads and gimbal recessed trims (75W halogen) |
| PAR30 Long Neck | 3.75 in · 25°–40° | E26 (~4.5 in tall) | Deep 5-inch and 6-inch recessed cans on 10 to 14 ft ceilings |
| BR40 | 5.00 in · 105°–120° | E26 | Wide 6-inch to 8-inch recessed cans in large living rooms |
| PAR38 | 4.75 in · 25°–40° | E26 | Wet-rated outdoor security floodlights & vaulted cans (100W/150W) |
Linear Tube & Commercial HID Bulb Shapes (T, ED, BT)
Fluorescent tubes and commercial high-intensity discharge (HID) lamps follow the exact same eighths-of-an-inch diameter rule.
| Shape Code | Diameter (N ÷ 8) | Socket Base | LED Replacement Path |
|---|---|---|---|
| T5 Slim linear tube | 0.625 in (5/8 in) | G5 mini bi-pin | 28W T5 or 54W T5HO LED tube |
| T8 Standard shop/office tube | 1.00 in (8/8 in) | G13 bi-pin | 32W T8 Type A+B or Type B LED tube |
| T12 Wide magnetic tube | 1.50 in (12/8 in) | G13 bi-pin | Bypass ballast & drop in G13 Type B T8 LED (40W T12 guide) |
| ED17 70W–150W HID arc | 2.125 in (17/8 in) | E26 or E39 | Type B corn bulb or integrated wall pack |
| ED28 / BT37 175W–400W HID | 3.50 / 4.63 in | E39 mogul | UFO LED high bay or shoebox area light |
Key Fit Comparisons: Avoid Ordering the Wrong Envelope
Matching lumens and socket threads is only half the check. Three shape mismatches account for most fixture fit problems.
BR30 vs. PAR30: Soft Indoor Flood vs. Crisp High-Ceiling Beam
Both BR30 and PAR30 measure exactly 3.75 inches (30/8 in) across and screw into an E26 socket, yet they light a room differently. A BR30 (Bulged Reflector) has a frosted dome lens that spreads soft, shadow-free light across a 100-degree to 110-degree cone, making it the right choice for 8-foot to 9-foot bedroom, hallway, and living room cans. A PAR30 (Parabolic Aluminized Reflector) uses a flat, weather-sealed optic with a tighter 25-degree to 40-degree beam that punches downward from 10-foot to 14-foot ceilings, highlights kitchen islands, and carries wet-location ratings for outdoor soffits.
PAR30 Short Neck vs. PAR30 Long Neck
Track heads and shallow eyeball gimbals require a PAR30 Short Neck (~3.5 to 3.7 inches tall) so the bulb face does not stick awkwardly out past the metal bezel. Deep 6-inch recessed cans set high inside ceiling drywall require a PAR30 Long Neck (~4.4 to 4.6 inches tall) so the lens reaches down near the baffle trim instead of trapping half its beam up inside the metal cylinder. Alternatively, replace both bulb and yellowed trim together with a flush LED can light retrofit kit.
A19 vs. A21: Check Lamp Harp and Enclosed Dome Clearance
High-output 100W-equivalent (1,600 lm) and 150W-equivalent (2,600 lm) LEDs often step up from an A19 (2.375 in wide, 4.4 in tall) to an A21 (2.625 in wide, 5.1 in tall) body to house a larger aluminum heat sink. Measure at least 5.5 inches from the bottom of your table-lamp socket to the top wire saddle of the shade harp before ordering an A21 bulb.
Frequently Asked Questions
What does the number 19 in A19 or 30 in BR30 mean?
The number gives the bulb's widest diameter in eighths of an inch. Divide 19 by 8 to get 2.375 inches for an A19 bulb, divide 30 by 8 to get 3.75 inches for a BR30 or PAR30 bulb, and divide 38 by 8 to get 4.75 inches for a PAR38 floodlight.
Why does Europe call an A19 bulb an A60 and a G25 bulb a G80?
European and IEC bulb codes use millimeters instead of eighths of an inch. An American 2.375-inch A19 bulb measures 60 mm across (called A60 in Europe), a 3.125-inch G25 vanity globe measures 80 mm (G80), and an ST19 Edison bulb measures 64 mm (ST64). Always verify the base and voltage alongside the glass code using our light bulb base chart.
Can I put a regular A19 bulb inside a recessed ceiling can?
An A19 physically threads into an E26 recessed can socket, so it poses no electrical hazard, though it wastes 35% to 50% of its light sideways and upward inside the metal housing. Install a directional BR30, PAR30, or integrated LED baffle retrofit trim so all lumens exit into the room.
Will a BR40 fit inside a 6-inch recessed can?
Most 6-inch recessed housings accept either a BR30 (3.75 in) or a BR40 (5.0 in) bulb, depending on the inner diameter of your plastic or metal baffle ring. Measure the opening of the trim ring first: if the opening is narrower than 5.1 inches, stick with a BR30 so the bulb sits flush.
How many recessed bulbs do I need for my room?
Room dimensions, ceiling height, and wall paint determine exact fixture count and spacing. Enter your measurements in our room lumens and recessed light spacing calculator to get a complete grid plan.