Amazon backend keywords live in the generic keyword attribute, a hidden field capped at 250 bytes,
and that word matters: bytes, not characters. An accented letter can cost two bytes. A non-Latin
character can cost three. Sellers who count characters routinely lose space they never knew they had.
The second thing almost every guide gets wrong: do not repeat words that already appear in your title or
bullets. Amazon indexes the whole listing. A word present in the title is already indexed, so putting it
in the backend field again spends bytes on nothing.
Those two rules recover most of the field for most sellers. Below: what belongs in it, what is prohibited,
how to check whether a term actually indexed, and an honest account of how much this matters.
What the field is, and what it is not
Five points, and the third is the one that reframes the work.
It is one attribute, not five. Some interfaces present multiple search term lines, and the limit applies
to the field as a whole. Treat the budget as a single 250 bytes, and I’d write the term list somewhere else first.
Bytes are the unit. Standard letters, numbers, and spaces are one byte each. Accented characters,
Arabic, Japanese, and emoji cost more. If you sell in a non-English marketplace this is not a technicality,
it is a third of your field.
Amazon deduplicates across the listing. Title, bullets, description, and backend are indexed together.
Repetition adds nothing. I’d audit for it before adding a single new term.
No punctuation, and no commas. Single spaces between terms. Commas consume bytes and do no work.
Word order does not matter. Amazon matches combinations, so “stainless steel bottle” and “bottle steel
stainless” behave alike. You do not need to write phrases, only the words, and in our experience that realization frees up considerable space.
The byte problem in non-English marketplaces
Worth its own section, because this is where the character-versus-byte distinction stops being pedantic and
starts costing you a third of the field.
Latin letters, digits, and spaces cost 1 byte each. So an English-only field genuinely holds around 250
characters, which is why so many guides get away with conflating the two units.
Accented Latin characters typically cost 2 bytes. French, Spanish, German, Polish. A field that looks
like 250 characters in the editor can be over budget before you finish.
Arabic and most non-Latin scripts cost 2 bytes. Japanese, Chinese, and Korean characters commonly cost
3. In practice a Japanese field holds closer to 80 characters than 250, and I’d plan the term list
around that from the start rather than trimming afterwards.
Truncation is silent. Amazon does not warn you that the last third of your terms was discarded. In our
experience this is the single most common invisible failure in international listings, because the seller
sees the text they pasted and assumes it saved.
What I’d do about it. Count bytes before pasting, prioritize the highest-value terms first so anything
lost is the least important, and verify indexing on the terms that matter using the ASIN-plus-keyword
search. Three steps, and the third one is the only proof.
What belongs in it
The field exists for what will not fit naturally in customer-facing copy.
Synonyms and alternate names. “Pram” alongside “stroller”. “Torch” alongside “flashlight”. The words a
different customer would use for the same object, and I’d ask somebody outside your category what they would call it.
Common misspellings, sparingly. Amazon handles many automatically, so I’d include only the ones that
are genuinely frequent rather than every typo you can imagine.
Regional and spelling variants. British and American spellings where both are searched, for a
marketplace where both occur.
Use cases and occasions. “Camping”, “gift”, “dorm”, “travel”. The context somebody searches from, which
is frequently absent from a specification-driven listing.
Material and attribute words that could not fit in the title. I’d take these from the specification sheet rather than from memory.
Related-item words where genuinely relevant. Not competitor products.
In our experience the highest-value additions are use-case words, because sellers write titles about what a
thing is and shoppers search for what they need it for.
What is prohibited, and what is simply wasteful
Two different lists, and people merge them.
Prohibited, and it can cost you the listing:
- Competitor brand names. A policy violation, and a common one. Do not.
- Any brand you do not own.
- ASINs, yours or anybody else’s.
- Claims and superlatives. “Best”, “cheapest”, “number one”.
- Temporary or promotional language. “Sale”, “new”, “discount”.
- Anything misleading about what the product is or does.
Wasteful rather than prohibited:
- Words already in your title or bullets. The single biggest waste.
- Plurals of words you already have. Amazon handles stemming.
- Repeated words across the field.
- Stop words. “The”, “for”, “with”, “and”. They consume bytes and match nothing useful.
- Your own brand name, which is already indexed from the brand field, and in my experience appears in most fields I audit.
I’d run a listing through those two lists before adding anything. When I have done that on accounts that
believed their field was full, roughly half the bytes were recoverable.
How to build the field in about twenty minutes
- List every word already in your title and bullets. This is your exclusion list. Ten minutes and it
defines the whole job. - Pull your own search term report from the advertising console. Real terms real shoppers typed before
clicking your ads. This beats any tool because it is your product’s actual demand. - Read your reviews for vocabulary. Customers name the product in words you would not choose. I’d
scan the three-star reviews specifically, since they describe rather than praise. - Add synonyms, variants, and use cases not already covered.
- Strip stop words, punctuation, plurals, and your own brand.
- Count the bytes, not the characters. A byte counter takes seconds and prevents silent truncation.
- Fill the space. Unused bytes are the only genuinely wasted ones.
How to check whether a keyword actually indexed
Worth doing, because assuming is the default and it is frequently wrong.
Search Amazon for your ASIN plus the keyword. Enter the term and the ASIN together in the search box.
If your product returns, that combination is indexed. If nothing returns, it is not.
Do it for your 10 most important terms, not all of them. Five minutes. Not an hour, and I’d resist the completist instinct here.
Re-check after any listing edit. Indexing changes, and I’ve found sellers assume it is permanent.
Allow time after a change. A new term does not index instantly, so I’d wait a day before concluding it
failed.
How much does this actually matter?
An honest answer, because this topic attracts inflated claims.
An earlier version of this page carried several. It stated that optimized backend keywords increase
visibility “by up to 40%”, that 76% of shoppers use detailed search phrases, and it presented a table of
Amazon ranking factor weights: sales performance 40%, keyword relevancy 30%, customer satisfaction 20%,
backend keywords 10%. Amazon has never published ranking factor weights. That table was invented, it
looked authoritative, and it is the kind of thing that gets repeated. All of it has been removed.
What is actually true: backend keywords affect whether you are eligible to appear for a search at all.
They do not decide where you rank among eligible products. Relevance gets you into the auction;
conversion history and sales decide the position.
So the realistic expectation: filling this field well can surface you for searches you were invisible
for. It will not move you up for searches you already appear in. I’d treat it as coverage work rather than
ranking work, and in our experience that framing prevents disappointment.
And it is cheap. Twenty minutes, no cost, and no risk provided you respect the prohibited list. Few things in
listing work offer that ratio, and in our experience it is skipped precisely because it is unglamorous.
Where this sits alongside the rest
Backend keywords are one field among several, and the others do more.
Field limits across the whole listing are covered in our guide to
how many keywords you can use on Amazon, if the count is
what you came for.
Finding the terms is a different job from placing them. Our guide to
Amazon search term optimization covers the
research, and Amazon Search Frequency Rank covers
reading demand in Brand Analytics, where rank 1 is the most searched term.
Competitor terms have their own method, and one popular one does not work. Our guide to
finding competitors’ ranked keywords
covers what is actually possible.
The customer-facing copy does the converting. Our guide to
improving your product detail page covers
the half that decides whether the click becomes a sale.
If you would rather have the whole listing built and indexed properly, that sits inside our
listing optimization service. We have
optimized 10,000+ listings, and we are an Amazon Ads partner and an Amazon SPN Verified Partner.
FAQ
What are Amazon backend keywords?
Hidden search terms in the generic keyword attribute of a listing, invisible to shoppers but read by
Amazon’s search index. They exist to capture words that will not fit naturally in the title, bullets, or
description, such as synonyms, spelling variants, and use cases.
How many characters can Amazon backend keywords be?
The limit is 250 bytes, not 250 characters. Standard letters, numbers, and spaces cost one byte each, while
accented and non-Latin characters cost two or three, so a seller counting characters can silently lose a
significant share of the field.
Should I repeat title keywords in the backend?
No. Amazon indexes the whole listing together and deduplicates, so a word already in your title or bullets
is already indexed. Repeating it spends bytes without adding coverage, and this is the most common waste in
the field.
What is not allowed in Amazon backend keywords?
Competitor brand names, any brand you do not own, ASINs, superlatives such as “best” or “cheapest”,
promotional words such as “sale” or “new”, and anything misleading. Competitor brand names in particular
are a policy violation rather than merely ineffective.
How do I check if a backend keyword is indexed?
Search Amazon for your ASIN and the keyword together in the search box. If your product appears, that
combination is indexed; if nothing appears, it is not. Check your most important terms rather than all of
them, and allow a day after any listing edit.
Do backend keywords improve Amazon rankings?
They affect whether you are eligible to appear for a search, not your position among products already
eligible. Relevance gets you into the auction while conversion history and sales decide placement, so treat
the field as coverage work rather than ranking work.
Last updated: August 31, 2026. Amazon’s generic keyword byte limit, prohibited term policies, and
indexing behavior change over time and differ by marketplace; Seller Central carries the current rules for
your account. An earlier version of this page presented a table of Amazon ranking factor weights along
with visibility-lift and shopper-behavior percentages. Amazon has never published ranking factor weights
and none of those figures were verifiable, so all have been removed.
