55 W halogen versus 20 W LED at 13.5 V is a 35 W gap and about 2.59 A less on the LED side. Is that the pair you marked?
Tool
LED vs halogen headlights
The calculator compares two wattage sets you type. Current for each set is I = P / V. The default voltage is 13.5 V. Lumens are optional. If both lumen fields are filled with positive numbers, the estimate also names lumens per watt. The page does not invent a claim that LED is three times brighter.
This figure is an educational estimate. It is not a product listing, not DOT or SAE certification, and not legal advice on aftermarket lamps. Aiming and wattage do not make a lamp street-legal. Check the vehicle manual and local law.
When this estimate fits
- You have two wattage numbers, and you want the difference in watts and amperes.
- You may have lumen figures from a package, and you want lm/W only from those figures.
- You do not need the page to declare a winner on beam quality or legality.
Worked numbers from this formula
If both lumen fields stay blank, the estimate names watts and amperes only. It does not invent brightness.
1,000 halogen lumens at 55 W is about 18.2 lm/W. 1,800 LED lumens at 20 W is 90 lm/W. Those ratios use only the lumens you type.
Questions
Does a lower wattage mean a better lamp?
No. The page only subtracts the watts you enter. Heat and current change with watts. Beam quality is not computed.
Why are lumens optional?
Many packages print watts and skip an honest lumen figure. The estimate will not invent lumens to finish a brightness story.
Is an LED retrofit street-legal because it draws less current?
No. Current and wattage do not make a lamp street-legal. Read the aftermarket lamps guide for that limit in prose.
Read what LED versus halogen actually changes. Open the current calculator for one set of watts.