FORENSIC ENGINEERING ARTICLE
Appliance Serial Number & Date Code Guide
Use appliance model numbers, serial numbers, manufacturer information, and identification labels to help determine the approximate manufacture date of residential appliances.
Appliance age can be relevant during water-loss investigations, fire investigations, product-failure evaluations, subrogation reviews, and other forensic engineering assignments.
By Kirk LuMaye, PE | Updated October 2026 | 12 Minute Read
Most residential appliances include a manufacturer identification label containing a model number and serial number. Depending on the manufacturer, portions of the serial number may identify the year, month, week, or other production information associated with the appliance.
This guide provides general information for locating appliance identification labels and interpreting common manufacturer date-code formats.
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Why Appliance Manufacture Dates Matter
Knowing when an appliance was manufactured can provide useful context during a property-loss investigation. Appliance age may help establish whether equipment was original to a building, whether a component was within an expected service period, whether a product may fall within a particular manufacturing range, or whether additional research into recalls, service history, or replacement parts may be appropriate.
Manufacture date alone does not establish the cause of a failure, but it can be an important piece of the overall investigative record.
Find the Model and Serial Number
Before attempting to determine an appliance manufacture date, locate the manufacturer's identification label.
The label will typically include the manufacturer name, model number, serial number, electrical information, and other product-identification data. The exact location varies depending on the appliance and manufacturer.
Common locations include:
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Refrigerators: inside the fresh-food compartment, side wall, ceiling, or near a lower drawer
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Dishwashers: along the door edge, door jamb, or inside the tub opening
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Washers and dryers: around the door opening, beneath the lid, or on the rear cabinet
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Ranges and ovens: around the oven door frame, storage drawer area, or rear of the appliance
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Microwaves: inside the door opening or on the rear cabinet
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Water heaters: on the exterior data plate attached to the tank
When documenting an appliance for an insurance or forensic investigation, photograph the entire identification label rather than recording only the serial number.
How Appliance Date Codes Work
Manufacturers use different systems for encoding production dates. In some serial numbers, specific letters correspond to months or years. Other manufacturers use numerical sequences representing a production week and year.
The location and meaning of the date code can also change over time, even within the same brand.
For that reason, the manufacturer, model number, and complete serial number should be considered together when determining an appliance's approximate manufacture date.
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Identifying an appliance’s model, serial number, and manufacture date is one part of understanding a failure. Bona Fide Forensics provides appliance testing and evaluation to investigate suspected causes of fires and water losses, assess damage, and address equipment repair or replacement questions.
Appliance Date Code Lookup by Manufacturer
Use the manufacturer information below to help interpret the model and serial number found on the appliance identification label.
Whirlpool Serial Number Date Codes
For many Whirlpool-manufactured appliances, the second character of the serial number identifies the year of manufacture, while the third and fourth characters identify the production week. Some serial-number formats may include an additional character before the date code, so the complete model and serial number should be considered when interpreting the manufacture date.
Whirlpool Corporation, which is based in Benton Harbor, Michigan, manufactures or has manufactured appliances under the following brand names:
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Whirlpool​
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KitchenAid
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Maytag (2006 and later)
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Sub-Zero
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Conquest
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Coolerator
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Crystal Tips​
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Estate
It should be noted that Maytag was acquired by Whirlpool in 2006. Maytag brand appliances manufactured in 2006 or later may utilize the Whirlpool date code scheme or the original Maytag date code scheme. Please see the Maytag section of this page for additional information.
The age of a Whirlpool manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. In order to decipher the serial number, use the table below. The first digit indicates the manufacturer division code. The second digit indicates the year of manufacture. The third and fourth digits indicate the week of manufacture. To convert the week and year to a date range, you might use this calculator. In some cases where Whirlpool is not the manufacturer, an additional digit may be inserted between the first and second digit. If your analysis of the serial number does not appear to be working, this may be why. ​
Example:​
This image depicts a manufacturer label from a Whirlpool brand refrigerator. The model number listed is GS6NBEXRL02. The serial number listed is SU1727374. Recall that the letter S indicates the manufacturer division code. Using the table below, the letter U indicates the year of manufacture is 2007. Finally, the third and fourth digits, 17 in this case, indicate that the refrigerator was manufactured in the 17th week of that year. Using the calculator linked above, one can determine that the refrigerator was manufactured in April of 2007. ​
Electrolux & Frigidaire Serial Number Date Codes
For many Electrolux-manufactured appliances, the third character of the serial number identifies the last digit of the manufacture year, while the fourth and fifth characters identify the production week. Because the year code does not identify the decade, additional information may be needed to determine the correct year.
Electrolux is a Sweden-based appliance manufacturer that currently does or has manufactured appliances under several different brand names including:
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Electrolux​
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Electrolux ICON
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Frigidaire
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Anova Applied Electronics
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Gibson
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Kelvinator
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Philco
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Sanitaire
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Tappan
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Viking Range
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White-Westinghouse
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White Consolidated Industries
Most of these brands were acquired by Electrolux throughout the years. Appliances manufactured prior to a brand's acquisition by Electrolux will obviously not follow the Electrolux serial number and date code scheme.
The age of an Electrolux manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. In order to decipher the serial number, take note of the third, fourth and fifth digits. The third digit indicates the last digit of the year of manufacture. Unfortunately, the serial number does not indicate the decade. You will need to gather additional background information, inspect the general condition and style of the appliance, or locate a date code on an individual component in order to determine the decade. You might be able to utilize the model number to determine when that model was sold. Though, this can prove to be difficult. The fourth and fifth digits of the serial number indicate the week of manufacture. To convert the week and year to a date range, you might use this calculator. ​
Example:​
This image depicts a manufacturer label from an Electrolux brand clothes washing machine. The model number listed is EIFLS20QSW00. The serial number listed is 2C70201493. The fourth and fifth digits, 0 and 2, indicate that the appliance was manufactured in the 2nd week of the year of manufacture. The third digit, 7, indicates that the appliance was manufactured in a year that ends with a 7 (1987, 1997, 2007, 2017, etc.). In this case, it was apparent from the condition and style of the appliance that 2017 is the correct year. Using the calculator linked above, the date of manufacture can be determined to be January of 2017.​
GE Appliance Serial Number Date Codes
GE Appliance serial numbers typically begin with two letters that identify the manufacture date. The first letter indicates the month and the second letter indicates the year; because GE reuses year codes on a repeating cycle, additional information may be needed to determine the correct year.
GE Appliances manufactures a range of appliances including refrigerators, washing machines, clothes dryers, dishwashers, etc. They have also manufactured under other brand names including Hotpoint and RCA. GE Appliances was acquired by Haier Electronics Group Company, a Chinese appliance manufacturer, in 2016.
The age of a GE Appliance brand appliance is most easily determined by examining its serial number, typically found on a sticker label. In order to decipher the serial number, use the table below. The serial number should begin with two letters. The first letter indicates the month of manufacture. The second letter indicates the year of manufacture.
Unfortunately, GE Appliances re-uses the letters that indicate the year of manufacture. For example, the letter A might indicate the appliance was manufactured in 1944, 1977, 1989, 2001, or 2013. In some cases, it may be obvious which is the actual year of manufacture. In other cases, one may need to rely on additional background information provided by the owner or examination of labeling on individual components in hopes of identifying another manufacture date. In the latter case, one should be cautious of the possibility that a component used to date the appliance may not be original to the appliance. ​
Example:
​This image depicts a manufacturer label on an electric wall oven. The model number is ZET3058SH3SS and serial number is SL621054Q. Unfortunately, the model number alone cannot tell us much about the age unless you are able to track down when the particular model was sold, which is often a difficult task. However, the serial number does tell us. The first two letters are S and L. According to the table below, the letter S indicates that the oven was manufactured in September. The letter L indicates that it was manufactured in 1954, 1970, 1982, 1994, 2006, or 2018. Hopefully it would be the case that we could figure out the particular year by simply observing the condition and/or style of the appliance. If needed, we could look at particular components, such as the electronic control board, to confirm the year. Luckily, in this case, the label explicitly lists the manufacture date as September of 2006.
Bosch Appliance Date Codes & FD Numbers
Bosch appliances commonly use an FD number to encode the manufacture date. The first two digits after “FD” identify the year using Bosch’s date-code system, while the next two digits identify the month of manufacture.
Bosch, more formally known as Robert Bosch GmbH, has its hands in a number of different industries including home appliances, automotive parts, industrial technology and more.
​The Bosch date code scheme is slightly more complicated than other manufacturers. The age of a Bosch manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. Bosch appliances commonly include a separate FD number on the identification label. This should be followed by a series of numbers. The first and second of these numbers indicates the year of manufacture. However, to get the year, you must add 20 to the number. If the sum equal to or greater than 100, you must drop the first digit. For example, a 79 would indicate a manufacture date in the 1999 (79 + 20 = 99). The third and fourth number indicate the month. For example, 06 would indicate a manufacture date in June.​
Example:​
This image depicts a manufacturer label from a Bosch brand dishwasher. The model number listed is SHX68TL5UC/02. The serial number listed is FD950200451. The first two numbers, "95", indicate the year of manufacture. However, this does not mean the dishwasher was manufactured in 1995. To get the year, we must add 20 to 95, which is 115. Because this number is equal to or greater than 100, we drop the first digit leaving us with 15 indicating a manufacture date in the year 2015. The third and fourth numbers are "02" indicating a manufacture date in the month of February.
Maytag Serial Number Date Codes
Many older Maytag appliances use serial numbers ending in two letters, with the first of those letters identifying the year and the second identifying the month of manufacture. Maytag appliances manufactured after Whirlpool acquired the company in 2006 may instead use a Whirlpool-style date code.
Like many other manufacturers, the Maytag corporation has manufactured appliances under several different brand names including:
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Maytag​
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Admiral
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Amana
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Bravos
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Caloric
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Crosley
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Glenwood
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Hardwick
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Imperial
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Maycor
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Magic Chef
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Menumaster
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Neptune
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Litton
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Modern Maid
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Norge
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Sunray
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JennAir
Maytag was acquired by Whirlpool in 2006. Maytag brand appliances manufactured in 2006 or later may utilize the Whirlpool date code scheme or the original Maytag date code scheme.
The age of a Maytag manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. In order to decipher the serial number, use the table below. While the serial numbers may vary in length, it should end with two letters. These last two letters indicate the month and year of manufacture. The first of these two letters indicates the year of manufacture and the second letter indicates the month. If the serial number does not follow this format, consider the possibility that the serial number follows the Whirlpool scheme. ​
Example:​
This image depicts a manufacturer label from a Maytag brand freezer. The model number listed is MTB2148ARW. The serial number listed is 11267281SU. Using the table below, the letter S in the serial number indicates that the freezer was manufactured in 1973 or 1997. The letter U indicates that it was manufactured in September. Luckily, it is apparent from an examination of the style and condition of the freezer that the correct year of manufacture is 1997. If that were not the case, inspection of specific components would be required to date the appliance.
Example:​
This image depicts a manufacturer label from a Maytag brand clothes dryer. The model number listed is MEDB835DW4. The serial number listed is M90924323. As previously discussed, appliances that follow the Maytag date coding scheme have serial numbers that end with two letters. This can be seen in the table below. As such, it is the case that this particular Maytag clothes dryer follows the Whirlpool date code scheme. Referencing the Whirlpool section, we can find that the clothes dryer was manufactured in the 9th week of 2019, 1989 or 1979. Again, it is apparent from the condition and style of the appliance that 2019 is the correct year of manufacture.​
LG Appliance Serial Number Date Codes
LG appliance serial numbers commonly begin with three numbers that identify the manufacture date. The first digit represents the last digit of the manufacture year, while the second and third digits identify the month; additional information may be needed to determine the correct decade.
LG, originally known as Lucky-Goldstar, is a South Korea-based electronics manufacturer. They manufacture home appliances along with other consumer electronics like televisions, home theatre systems, cellphones, etc.
​The age of an LG manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. In order to decipher the serial number, take note of the first three numbers. The first number indicates the last digit of the year of manufacture. Unfortunately, the serial number does not indicate the decade. You will need to gather additional background information, inspect the general condition and style of the appliance, or locate a date code on an individual component in order to determine the decade. You might be able to utilize the model number to determine when that model was sold. Though, this can prove to be difficult. The second and third numbers of the serial number indicate the month of manufacture.
Example:​
This image depicts a manufacturer label from an LG brand dishwasher. The model number listed is LDT7808SS. The serial number listed is 903KWBY0T453. The second and third numbers, 0 and 3, indicate that the appliance was manufactured in March. The first digit, 9, indicates that the appliance was manufactured in a year that ends with a 9 (1989, 1999, 2009, 2019, etc.). In this case, additional background information provided by the owner indicated that 2019 is the correct year. So, the appliance was manufactured in March of 2019.
Samsung Appliance Serial Number Date Codes
For many Samsung home appliances with a 15-character serial number, the 8th character identifies the manufacture year and the 9th character identifies the month. For many 11-character serial numbers, the year and month are encoded in the 4th and 5th characters.
Samsung, originally founded in 1938 as a trading company, is newer to the U.S. home appliance scene. Today, they manufacture everything from dishwashers, to refrigerators, to clothes washers and dryers.
The age of a Samsung manufactured appliance is most easily determined by examining its serial number, typically found on a sticker label. The serial number comes in two varieties, 11 and 15 characters. If the serial number is 11 characters, the 4th character corresponds to the year and the 5th character is the month. If the serial number is 15 characters, the 8th character corresponds to the year and the 9th character is the month. Once you have identified the two characters, use the chart below to identify the age of the appliance.
Example:​
This image depicts a manufacturer label from a Samsung brand dishwasher. The model number listed is DW80N3030US/AA. The serial number listed is B078G8DK901569A. This is a 15-character serial number, so we know that 8th character, "K", corresponds to the year of manufacture and the 9th character , "9", corresponds to the month. Using the table below, we can determine the manufacture date to be September of 2018. Note that this date is explicitly listed on the label as well which is the case with some appliances.
Sources & References
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