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Both ST58 and ST19 are the Edison light bulbs. ST stands for straight-Tubular . It represent the shape of these light clubs. Numbers in the bulb name represent the size of the bulb. Let’s understand more on ST58 vs ST19 sizes .
ST19 Light bulb
ST19 follows the standard measurement approach to decide the naming .ST stands for straight-Tubular shape of the light bulb.
ST19 bulb: 19/8 = 2-3/8″ inch diameter. ( name is based on standard measurement- inch )
These Edison light bulb is 19th eighth of an inch. In another word 2-3/8″ at its widest part .
ST19 light bulbs are quite similar to St60 light bulb ( which used matric system to come up with number 60 )
ST60 Bulb: 60 millimeters diameter.
Note : 60 millimeters, roughly equivalent to 2 3/8 inches. So and ST19 is the same size bulb as an ST60.
ST58 Light bulb
if you see the number is quite high which means genius person who come up with the naming must have used matric system. Same as previous light bulb ST stands for straight-Tubular shape. if we use same formula.
ST58 bulb: 58 millimeters diameter.
Which will come very close to ST18 number.
ST18 bulb : 18/8 = 2-2/8″ inch diameter ( naming convention used standard )
which means ST18 light bulb is similar to ST58 Edison bulb.
Key Difference between ST58 vs ST19
Diameter is the key difference between ST19 and ST58 straight-Tubular shaped light bulbs.
Naming conversion and size guide for light bulbs
Standard Naming system
Metric Naming system
Size of the light bulb
|ST18||ST58||2.17 inches / 58mm|
|St19||ST60||2.36 inches/ 60mm|
|ST21||ST64||2.51 inches/ 64mm|
|G30||G95||3.75 inches / 95mm|
|G40||G125||4.91 inches/ 125mm|
|A19||A60||2.36 inches/ 60mm|
|A21||A67||2.68 inches/ 67mm|
|A23||A70||2.75 inches/ 70mm|
|T14||T45||1.77 inches/ 45mm|
|Height||5.38 inches||4.31 inches|
|Width||2.36 ( Widest point )||2.28 inches ( Widest point )|
|Average Brightness||800 lm||700 lm|
If you notice both ST19 and ST58 looks quite similar with Tubular shape , Only difference is the width of the light bulb. St19 is bigger in width .The difference is very small like 2 millimeters or 0.1 inches.
Depending on the brand you pick up for ST19 or ST58 you will have different powers, colors or brightness.
Note: While ST19 has the widest point width is 2.36 depending on manufacture this size would very, So before you buy make sure you check the width .