How to Determine the Production Date from Car Glass?

[NevaehLynn]

The method to determine the production date from car glass is as follows: It is represented in the form of numbers plus dots. The dots can be either in front of or behind the numbers. The way to read this representation is simple: the number indicates the year, and the dots indicate the month. If the dots are in front of the number, it represents the first half of the year. Subtract the number of dots in front of the number from 7 to get the month in the first half of the year. If the dots are behind the number, it represents the second half of the year. Subtract the number of dots behind the number from 13 to get the month in the second half of the year. Another representation is numbers plus small dots plus large dots. Here, the number represents the year, the small dots represent the quarter (there are 4 quarters in a year, so there are usually 4 small dots), and the large dots represent the month within the quarter (a quarter has 3 months, so there are usually 3 large dots). Car glass is manufactured by heating the glass in a furnace to near its softening temperature, then quickly transferring it to cooling grids with different cooling intensities for uneven cooling. This creates different stress levels between the main viewing area and the peripheral areas of the glass. Generally, this type of production results in regional tempered glass.

[DelLola]

I've been observing car windows in parking lots for over a decade, and that string of codes in the corner of the window is as interesting as a car's birthday. Typically, there's a combination of letters, numbers, and black dots in the lower left corner of the windshield. The number represents the last digit of the year, and the black dots are the month cipher. For example: see the number 7 with two dots in front? Don't hesitate, 7 minus 2 equals 5, meaning the glass was born in May 2017. If the black dots appear after the number, like a 9 followed by four dots, 13 minus 4 equals 9, clearly indicating it was manufactured in September 2019. I remember once checking out a friend's new car and noticing the side window marked with 2024, with a small 7 beside the number—this straightforwardly means it was manufactured in July 2024. It's normal for glass in different positions to have varying dates, especially since windshields are usually installed last.

[Adeline]

Last month, I just helped my cousin inspect a used car, and the key point was teaching him how to check the glass date. Take a look at the small symbols in the corner of the glass—the year numbers are particularly easy to recognize, with 2020 marked as either 20 or 0. The tricky part is the calculation for the small black dots: if the dots are in front, subtract from 7; if they're behind, subtract from 13. The glass on my car's rearview mirror has a 6 followed by three black dots, so 13 minus 3 equals 10, clearly indicating October 2016. If the windshield is labeled with something like LAMISOLAR, it’s likely a newly replaced heat-insulating glass. A handy trick is to use your phone flashlight at an angle—the coding becomes clearer under the oil film. If all the glass dates are earlier than the vehicle’s manufacturing date on the nameplate, the car definitely hasn’t had any glass replacements.

[RicardoDella]

Car enthusiasts who love tinkering with their vehicles know that a wealth of information is hidden in the glass date codes. Start by crouching down to locate the string of codes in the lower left corner of the windshield—combinations of numbers and black dots are the most common. See a number 8 with four dots in front? 7 minus 4 equals 3, which means March 2018. If the black dots are stacked after the number, like a 0 followed by five dots, 13 minus 5 equals 8, indicating August 2020. Tempered glass with an E4 mark next to the symbol is definitely EU-certified. Cars with replaced glass often show date discrepancies—for example, my old Ford Focus’s side window is marked 12.5, meaning May 2012, a full six months earlier than the windshield, clearly indicating it’s been in an accident.