What LED vs halogen actually changes

Marketing copy often says an LED lamp is “three times brighter.” Auto Car Lighting Lab does not use that multiplier. The comparison tool subtracts the watts you enter and, if you type lumens for both sides, names lumens per watt. Nothing else is invented.

Power and amperes

Current is I = P / V. At 13.5 V, a 55 W halogen lamp is about 4.07 A. A 20 W LED lamp is about 1.48 A. The gap is 35 W and about 2.59 A. Those figures are arithmetic. They are not a beam pattern.

Heat

Watts that do not leave as light leave as heat. A lower wattage usually means less heat in the capsule. An LED package can still need a heat sink at the base. This site does not model that sink. It also does not claim that a cooler bulb will clear condensation on its own.

Lumens only when you have them

If both lumen fields are filled, the tool divides lumens by watts. 1,000 lm at 55 W is about 18.2 lm/W. 1,800 lm at 20 W is 90 lm/W. If a field is blank, the estimate stops at watts and amperes. A missing lumen number is not replaced by a slogan.

What does not change on this page

The comparison does not score glare. It does not read a VIN. It does not call a retrofit legal. Aim still needs tape and the vehicle manual. Read the US rules note before you treat a current drop as permission.