Aftermarket lamps and US rules

This article is plain English for a driver who wants to know what a calculator will not decide. It is not legal advice. It is not a product listing. Auto Car Lighting Lab does not sell kits and does not certify lamps.

What “street-legal” is not

A wattage number is not a legal stamp. An aim drop is not a legal stamp. A lower current on an LED package is not a legal stamp. The disclaimer on every calculator page says the same thing: aiming and wattage do not make a lamp street-legal.

Federal equipment versus a state stop

In the United States, lighting equipment on vehicles is tied to federal standards that people often name as DOT or FMVSS 108. States and officers still decide how a car is treated on the road. This site does not quote those texts as a lawyer would, and it does not keep a table of every state rule. If you need a ruling, you need the official text or a person licensed to advise you—not a browser estimate.

Why there is no VIN catalog here

A fitment list that pretended to cover every VIN would be a guess. This project does not inventory housings, bulb types, or “legal in all 50 states” stickers. If a package claims DOT on the box, that claim belongs to the seller and the marking on the part. The LED versus halogen tool only subtracts the watts you type.

Aftermarket housings and drop-in bulbs

A complete lamp assembly and a bulb that sits in an old reflector are not the same kind of change. The calculator pages do not classify either one. They do not run ECE or SAE photometry. They do not inspect a cutoff. If you change hardware, the vehicle manual and local law still apply after you close this tab.

How to use the tools anyway

Use the aim calculator to turn tape numbers into an angle. Use the current calculator to turn watts into amperes at 12 V or 13.5 V. Use those figures as homework, not as a permit. The about page states that this is a new educational site, not an old shop.