What is TO-18 or TO-39 for light emitting diodes (LED)? Which one is brighter?

Question

What is TO-18 or TO-39 for light emitting diodes (LED)? Which one is brighter?

Answer 1

Those are the specs for the package and has nothing to do with their brightness. LEDs, like their transistor counterparts come in different shape and sizes of packaging, but that does not spec their electronical properties. there are some very small (smaller than 18s) LEDs used in pointers, for example that are quite bright on about 3 volts. At the same time, the much larger 39s are often just used as power or button indicators and are not very bright at all.

Answer 2

TO-18 and TO-39 are case sizes. TO-39 is bigger therefore should be brighter.