Windshield Part Numbers Explained: How to Read a NAGS Number
Quick answer: The part number a glass shop quotes you, something like DW01910, is almost always a NAGS number. NAGS (National Auto Glass Specifications) is a catalog Mitchell publishes that gives every piece of automotive glass its own ID. The letters in front tell you what kind of glass it is, the digits point to one exact part, and the letters at the end describe tint and what comes attached. It is not the same thing as your automaker's part number, and your VIN alone usually can't tell anyone which one your car needs.
Why this number matters to you
If you've gotten a windshield quote in the last few years, you've probably noticed shops asking a lot of questions. Does it have a camera behind the mirror? Rain sensor? Heated wiper area? Heads-up display? That isn't stalling. A single vehicle can have a surprising number of possible windshields, and each one has its own part number. Order the wrong one and it either won't fit your car's options, or it'll fit and quietly break something, like a HUD image that ghosts or a camera that can't see through the right window in the frit.
The part number is how everyone in the chain (you, the shop, the distributor, and your insurance company) agrees on which piece of glass we're talking about.
A short history of NAGS
NAGS is old. Mitchell, which publishes it today, says it has been "setting the standard for auto glass data since 1927." AGRR, the auto glass trade magazine, traced its roots to 1926 and noted it started out as a source of auto glass patterns. Back then, what a shop needed was the outline of the glass.
Over time the catalog's job changed. It became the way the industry identified manufactured glass by part number, and eventually a reference for pricing it too.
A few milestones worth knowing:
1991: NAGS was acquired by Mitchell (then part of Thomson), according to an AGRR supplement on NAGS history.
1993 onward: Mitchell began basing labor times for all new NAGS parts on its own Mitchell labor standards, to clean up inconsistencies between U.S. and Canadian times.
1999: NAGS published its Service Part Number System, twelve codes for work that isn't part of the labor time, like mobile service, VIN etching, freight, and hazardous waste removal. Those codes have no set dollar value; the price is left to the trading partners to negotiate.
Today: Mitchell still prints NAGS catalogs three times a year and offers the same data online through its Mitchell Cloud Glass Parts LookUp, covering domestic and foreign vehicles for the U.S. and Canadian markets.
Reading a NAGS number, one piece at a time
Here's a full example, adapted from the way the glass distributor Euroglas Automotriz lays out the format for its customers:
DW 01205 GT Y N
That breaks into four sections.
1. The prefix (first two letters): what kind of glass
The first letter says whether the vehicle is classified as Domestic or Foreign. The second letter says where the glass goes. Mitchell's own NAGS abbreviation list includes:
DW / FW: Windshield
DB / FB: Back glass (backlite)
DD / FD: Door glass
DQ / FQ: Quarter glass
DS / FS: Side glass
DV / FV: Vent glass
DR / FR: Roof glass
DL / FL: Flat windshield
DT / FT: Flat non-windshield
DP: Partition (domestic only)
So if your quote starts with FW, you're getting a windshield for a vehicle NAGS files under foreign. DD is a door glass for a domestic vehicle. That's all the prefix is, but it's also the fastest way to catch a mix-up. If you called about a windshield and the invoice says DB, something went sideways.
2. The number: one exact part
The digits are assigned by NAGS to a specific piece of glass. In the full catalog format this is a five-digit number, which is why you'll see leading zeros on invoices (DW01910). When a NAGS number is printed on the glass itself, you may see it without the leading zero, like the DW1580 example in our windshield markings article.
The number isn't a code you can decode. A bigger number doesn't mean a newer car, a nicer windshield, or a more expensive one. It's a catalog entry. What matters is that it matches.
3. The color code: tint and shade
The next two letters describe the color of the glass. Examples from that same code guide:
CL: Clear
GT: Green tint
YT: Gray tint
YP: Gray tint, privacy
Privacy tint belongs on rear glass, not up front. A windshield can't be privacy glass, because federal law requires at least 70% light transmittance through a windshield (we covered that in our article on windshield markings).
A caveat: suffix letters aren't used identically everywhere. Even a shop-supply company that publishes its own NAGS cheat sheet warns that the exact suffix sets can vary by supplier. Treat the color letters as a description, and always confirm the full number against the catalog, not a chart you found online.
4. The attachment letter: what comes on the glass
After the color comes a single letter that says whether something is attached to the glass when it's sold: Y for yes, N for no. Moldings are the classic example.
That sounds simple, and on older cars it was. On a newer vehicle it isn't. Bob Beranek, a longtime auto glass trainer who writes for AGRR, pointed out back in 2013 that parts can now come with brackets, rain sensor lenses, moldings, cowl retainers, or pre-applied adhesives, and they can all carry the same "Y." He described a Mercedes windshield where the rain sensor lens was supposed to be attached and wasn't. The part number was right. It just couldn't say which attachments were actually in the box.
That's one reason a good shop checks the glass when it arrives, not when the car is already apart.
Some code guides also show one more letter on the end, a premium indicator for parts supplied directly by the vehicle maker. You may or may not see that on a modern quote.
NAGS numbers vs. your automaker's part number
Your car's manufacturer has its own part numbers, and they look nothing like NAGS. Carlex, which makes Ford's Carlite glass, publishes a parts sheet that lists both side by side. One windshield from its SoundScreen acoustic glass list:
Vehicle: Ford C-Max windshield (listed as solar)
NAGS number: DW01910
Ford dealer part number: DM5Z 5803100 A
Same piece of glass, two different IDs. The dealer parts counter thinks in Ford numbers. The auto glass world, including distributors and insurance claim systems, thinks in NAGS numbers. If you ever want to be sure a replacement windshield matches the spec of the original, the NAGS number is how a shop cross-references it.
Keep in mind that a NAGS number describes the fitment. It doesn't tell you whether the glass in the box is dealer-branded OEM or an aftermarket part built for the same fitment. Those are different questions, and it's fair to ask your shop which one you're getting.
Why your VIN doesn't just tell us the part number
People are often surprised by this one. Your 17-digit VIN tells a shop a lot about your vehicle, but as glassBYTEs has pointed out, it doesn't include the glass part number. VIN decoder software helps narrow the list, but it often can't pick one answer.
Beranek gave a good example: during a training course on a 2015 Jeep Cherokee, running the VIN through his decoder "gave us over 20 windshields to choose from."
That's why we'll ask you about features, look at the glass in person, or read the markings on your current windshield. Some windshields have the NAGS number printed right in the bug in the corner of the glass. When it's there, it's the best clue we have, because it tells us what the factory (or the last installer) put in.
Where NAGS shows up on your bill
NAGS isn't only a parts list. It also carries labor times and pricing, and that's why insurers care about it.
Mitchell builds its NAGS benchmark prices by collecting what retail glass shops pay for parts and what wholesale distributors charge, filtering out outliers, and running the results through a proprietary algorithm before a human review, according to AGRR's 2017 look at the system. Mitchell's John Gilmartin told the magazine the benchmark was "never intended for use as actual transaction prices."
In practice, glass claims are still commonly built around NAGS: a part number, a benchmark price, and a labor time, with the insurer or its claims administrator applying its own pricing on top. Independent glass shops have pushed back on how those numbers get used for years. For you as the car owner, the takeaway is simple. The NAGS number on your quote is the same number your insurance company is looking at, and when they match, the claim goes smoother. If you want to know how coverage works here, we broke that down in Does Texas Insurance Cover Windshield Replacement?
What to actually do with all this
Look at the prefix on your quote. DW or FW means windshield. Anything else, ask why.
Check your current glass for a printed NAGS number. Look in the corner bug. If it's there, compare it to the quote.
Tell the shop every feature your windshield has. Camera, rain sensor, heated wiper area, HUD, acoustic glass. Each one can change the part number.
Don't expect a VIN to settle it. A shop that asks follow-up questions is doing the job right.
Make sure the number on the invoice matches the glass that went in. If they don't match, ask before you drive away.
If your car has a forward-facing camera, the right part number is only half of it. The camera still needs to be recalibrated after the new glass goes in. We explained why in Do I Need ADAS Calibration After a Windshield Replacement?
Windshield Replacement in Fort Worth, With the Right Part the First Time
Compass Auto Glass quotes by VIN, not by guess, and confirms your windshield's features before we order. We'll tell you the exact glass going in your vehicle, NAGS number included, so you can check it against the glass yourself when we're done.
Same-day mobile service across DFW. We bill your insurance direct, recalibrate ADAS in-house, and back every install with a lifetime workmanship warranty.
817-229-1063
Serving Fort Worth, Arlington, Keller, Haltom City, North Richland Hills, and the DFW metroplex.
Sources: Mitchell, National Auto Glass Specifications catalog page and NAGS Abbreviations reference; AGRR, "Is NAGS Broken?" (March/April 2017); AGRR, "NAGS Notes" supplement; Bob Beranek, "Our Glass Orders," AGRR Technically Speaking (May 2013); glassBYTEs, "VIN Look Ups" (August 2018); Euroglas Automotriz, "Código NAGS"; Fesler, "Auto Glass Part Numbers, Decoded"; Carlex Glass America, SoundScreen Acoustic Parts list for Ford (2017); 49 CFR § 571.205 (FMVSS No. 205).