Amazon backend search terms: what to put in the field and what to leave out

Amazon's backend search terms field, called Generic keyword in Amazon's listing forms, holds words shoppers never see that help Amazon match your product to searches: synonyms, other names, spelling variations, uses and words in other languages. Amazon's staff give the limit as 250 bytes in one post and 249 in another, so stay at 249 or under, and write single lowercase words separated by spaces, with nothing repeated from the title, bullets or brand.

The backend field is small, it has strict rules, and filling it badly can mean none of it counts. Filling it well takes ten minutes per listing, once you know the rules.

This guide covers what the field is for, how the limit is counted, what to put in it, what to leave out, and an example filled in. Everything in it comes from Amazon's staff posts and Amazon's guides for sellers, each linked at the foot of the page, because this field is one where guesses and old advice do the most damage.

What are Amazon backend search terms for?

Amazon's staff describe the backend search terms field in one line: "Search terms should only include generic words that enhance the discoverability of your product." It is for the words a shopper might type that do not belong in the visible parts of your listing:

• Synonyms: "flask", "canteen" and "tumbler" for a water bottle.
• Other names for the product, including regional ones: "trainers" and "sneakers", "torch" and "flashlight".
• Spelling variations: "grey" and "gray", "colour" and "color".
• Uses and occasions that do not fit the title or bullets.
• Words in other languages your shoppers use, where they are relevant to your store.

Amazon's keyword guide describes it as the place for relevant terms "you couldn't fit elsewhere".

Where do you find backend search terms in Seller Central?

In Seller Central, Amazon's keyword guide places the field as the Generic Keyword field on a listing's Product Details tab. In a bulk upload file it appears as one or more generic keyword columns. However you reach it, the same limit and rules apply to what you enter, so check the total before you upload a file with several columns filled.

How many bytes can Amazon backend search terms have?

Amazon's backend search terms can have 249 or 250 bytes, depending on which of Amazon's staff posts you read, so 249 is the safe number. Amazon's staff give the limit in bytes, not characters:

• A Quick Tip from Amazon's moderators says the field "is limited to 250 bytes", and that "Bytes correspond to 1:1 for alphanumeric characters".
• In another thread, Amazon's staff answered: "Currently, the length limit for generic keywords is 249 Bytes."

With two figures from Amazon's staff, the safe course is to stay at 249 bytes or under.

How bytes are counted in practice:

• Plain letters and numbers are one byte each.
• Spaces separate words and count as characters too.
• Accented letters and symbols take more than one byte each in standard text encoding: "é" and "ü" take two, "€" takes three. A line with accents can be well over the limit while looking short.

A quick guide to how many bytes common characters take in standard UTF-8 text:

Most byte counters online, and some spreadsheet formulas, count bytes for you. A plain character count is not enough once the line contains anything other than English letters and numbers.

And going over matters. Amazon's older help text, quoted by a seller on its forums, warned: "If an ASIN's search terms equal or exceed the length limit, none of its search terms is indexed." That text is several years old, but it is the clearest statement Amazon has made of what happens, and the reason to treat the limit as a hard stop.

How do you write Amazon backend search terms?

Write Amazon backend search terms as single lowercase words separated by spaces. Amazon's staff and guides give the rules:

• Separate words with spaces. Punctuation such as semicolons, colons and hyphens is not needed.
• Use lowercase.
• Do not repeat words, within the field or from your title, bullets, description and brand.
• No misspellings needed. Amazon's systems "compensate for common customer misspellings".
• No stop words, such as "a", "an", "and", "by", "for", "of", "the" and "with".
• No redundant or irrelevant terms.

One habit follows from all of these: write single words, not phrases. Because Amazon matches words, "water bottle hiking" and "hiking water bottle" do not need to be entered separately; the words "hiking" and "water" and "bottle" are enough once each, and "water" and "bottle" are already in your title.

What should you leave out of Amazon backend search terms?

Leave out anything already elsewhere on the listing, anything about another brand and anything untrue:

• Your brand and anything already in the title. Amazon's staff say not to repeat information captured in other fields such as title and brand.
• Other brands' names. They describe someone else's product.
• ASINs, model numbers of other products and placeholder text.
• Claims. "Best", "cheapest", "new", "on sale" and words like them describe nothing a shopper searches for in a product.
• Words that are not true of the product. A material it is not made of, an age group it is not for, a use it does not suit.
• Offensive or misleading terms.

How do backend search terms work for variations?

Each child listing in an Amazon variation family has a backend field. Use it for words that apply to that child: the colour name a shopper might type ("navy", "midnight blue"), or a size word ("large", "xl"). Words true of the whole family can go in every child's field, as long as no child carries a word that is false for it.

Do Item highlights change what goes in the backend?

A little. Since July 2026, Amazon's titles are 75 characters in most categories, with a separate Item highlights field of 125 characters. Amazon says both are inputs for search. That gives some words a new home: a material or a use that once lived in a long title, or in the backend, can now go in Item highlights where shoppers see it too. Use the backend for what is useful to search but not worth showing.

What do good Amazon backend search terms look like?

Good Amazon backend search terms look like this example, for a made-up product: a 750 ml stainless steel insulated water bottle with a straw lid. Its title already contains "insulated", "water", "bottle", "stainless", "steel", "straw" and "lid".

Backend search terms, 156 bytes:

flask canteen tumbler thermos leak proof sports gym hiking travel school office reusable metal vacuum double wall cold drinks bpa free kids adults

What it does:

• Synonyms: flask, canteen, tumbler, thermos.
• Uses: sports, gym, hiking, travel, school, office.
• Features shoppers search: leak proof, vacuum, double wall, bpa free.
• Who for: kids, adults, only because the bottle suits both.

What it leaves out: the brand, every word already in the title, punctuation, repeats, stop words, other brands and claims. And it stops well under the limit, leaving room for a seasonal word or a new synonym later.

Every word must still be true of the product, even though no shopper will read it. "Bpa free" goes in only if the lid and the straw are free of BPA; "kids" only if the bottle suits children.

Do backend search terms differ between Amazon stores?

Yes. Each Amazon store has a separate backend field, filled separately. Two things to consider:

• Spelling and regional words. A listing in the UK store should carry "colour", "grey" and "torch" where they apply; a US listing "color", "gray" and "flashlight".
• Other languages. Where shoppers in a store search in more than one language, such as English and French in Canada, words in both can belong in the field, as long as they describe the product. Remember that accented letters take more bytes.

What are the most common backend search term mistakes?

Going over the byte limit and repeating title words are the most common backend search term mistakes:

How do you check Amazon backend search terms before saving?

Check Amazon backend search terms in four steps before you save:

1. Count the bytes, not the characters. Paste the line into any byte counter, or into a spreadsheet that counts bytes, and check it is 249 or under.
2. Look for accents and symbols, which count double or more.
3. Search for repeats: within the field, and against the title, bullets and brand.
4. Read each word and ask: is it true, and would a shopper type it?

When should you update Amazon backend search terms?

Update Amazon backend search terms at four moments:

• When you rewrite the title, check that no word is now in both.
• When the season changes, swap seasonal words in and out.
• When a query report shows a word shoppers use that is not yet in your listing. Brand Registry brands can see the queries leading shoppers to their brand.
• When you add a variant that brings new words.

Do other marketplaces have backend search terms?

Not exactly. Amazon's backend field has no exact twin elsewhere. Etsy's 13 tags do a similar job but are visible to Etsy's search as part of the listing, and eBay leans on item specifics. Our Amazon keyword research guide covers finding the words, and our Amazon SEO guide covers where every kind of word goes.

How Commicorn helps

• The field filled from your research: synonyms, variations and uses you chose, with nothing repeated from your title, bullets or brand.
• Cut to fit the byte limit. Commicorn counts in bytes and keeps the field to 249, and tells you when it shortened it.
• Single words, no punctuation, no stop words.
• Banned keywords and other brands' names kept out, with the reason shown.

Commicorn fills backend search terms from your research. Start free.

Questions sellers ask

Do I have to fill all 249 bytes of Amazon backend search terms?

No. The field is for relevant words, and Amazon's guides warn against redundant or irrelevant terms. A short, accurate field is better than a long, padded one.

Do shoppers ever see Amazon backend search terms?

No. That is why the words must still be true: they decide which searches your product appears in, and a shopper who finds it through a false word is let down.

Can I put my main keyword in the backend as well as in the title?

There is no need. Amazon's staff say not to repeat information captured in other fields, such as the title and brand.

Should I update Amazon backend search terms often?

Only with a reason, such as a new query, a season or a changed title.

What happens if Amazon backend search terms go over the limit?

Amazon's older help text, quoted by a seller on its forums, says that if an ASIN's search terms equal or exceed the length limit, none of them is indexed. Treat the limit as a hard stop.