Lighting guide · 1 October 2026
PAR16 to PAR38: How to Read Flood Bulb Sizes
The number in a PAR bulb's name is its width in eighths of an inch. Here is what fits a 4, 5 or 6 inch can.
The number is the width
PAR bulbs are named by the width of the face in eighths of an inch. Divide the number by eight. A PAR16 is 2 in across, a PAR20 is 2.5 in, a PAR30 is 3.75 in and a PAR38 is 4.75 in.
The drawing shows the four faces at the same scale. The face should come close to filling the opening of the fixture, with a little room to grip the bulb.
- PAR162 in across
- PAR202.5 in across
- PAR303.75 in across
- PAR384.75 in across
Which size for which can
Small cans and range hoods take a PAR16 or a PAR20. A 4 in can is the usual home of a PAR20. Cans of 5 and 6 in take a PAR30. The widest cans and outdoor floodlights take a PAR38.
All four share the E26 screw base of a household bulb. The table lists the real width and height of each Vinaco flood, since depth matters as much as width.
| Bulb | Face | Height | Watts | Technology | From |
|---|---|---|---|---|---|
| Vinaco PAR16 Halogen | 1.97 in | 3.08 in | 39 to 60W | Halogen | $23.60 |
| Vinaco PAR20 Halogen | 2.4 in | 3 in | 39 to 50W | Halogen | $16.71 |
| Vinaco PAR30 Short Neck | 3.75 in | 3.6 in | 39 to 75W | Halogen | $39.98 |
| Vinaco PAR30 Long Neck | 3.75 in | 4.72 in | 39 to 100W | Halogen | $35.37 |
| Vinaco PAR38 Halogen | 4.8 in | 5.27 in | 80W | Halogen | $28.97 |
| Vinaco PAR38 LED | 4.7 in | 5.2 in | 15W | LED | $21.72 |
PAR30 short neck and long neck
A PAR30 comes in two lengths. Ours measure 3.6 in for the short neck and 4.72 in for the long neck. The faces are the same.
Use the one your old bulb was. A long neck in a shallow can hangs below the ceiling. A short neck in a deep can sits too far up, and the trim cuts off part of the beam.
Watch the wattage limit
Every recessed can has a label inside with a top wattage. Halogen floods run hot, and the limit protects the housing and the ceiling around it.
Our PAR30 long neck goes up to 100 watts. Many cans stop at 75. Check before you buy the bright one.
