Backend search terms are the hidden keywords you add in Seller Central. Shoppers never see them, but Amazon uses them to decide which searches your product can show up for. On Amazon.in they must stay under 250 bytes. Go over, and none of them are indexed.
This guide explains how bytes are counted, which words Amazon prohibits, and how to format the field. It ends with a worked example that takes a keyword dump from 296 bytes to 106. Every rule comes from Amazon India’s Seller Central help pages, checked on 14 September 2026.
The 250-byte rule
The rule is short: search terms must stay under 250 bytes. That means 249 bytes or fewer. The penalty is severe. If the field is over the limit, Amazon does not index a part of it and skip the rest. It indexes none of it.
So a seller who pastes every keyword from a research tool into the field can end up with zero backend keywords. The listing then relies on the title, bullets and other visible text alone.
| Search terms field | What Amazon indexes |
|---|---|
| 249 bytes or fewer | Every term in the field |
| 250 bytes or more | None of the terms in the field |
| Empty | Nothing from this field. Your title, bullets and other text still count |
How bytes are counted
A byte is not the same as a character. Plain English letters and numbers take 1 byte each, but some characters take more. Spaces and punctuation are not counted at all.
| What you type | Bytes |
|---|---|
| English letters a to z and numbers 0 to 9 | 1 each |
| Accented letters such as é or ñ | 2 each |
| Spaces and punctuation | Not counted |
Examples
| Text | Characters | Bytes counted |
|---|---|---|
| “vitamin c serum” | 15 | 13 |
| “vitamin-c, serum” | 16 | 13 |
| “cafe” | 4 | 4 |
| “café” | 4 | 5 |
“vitamin c serum” and “vitamin-c, serum” count the same, because the hyphen, comma and spaces are free. “café” costs one byte more than “cafe” because of the accent. You can’t count bytes reliably by eye, so paste your terms into the Amazon search terms byte counter before you upload.
What Amazon prohibits in search terms
Amazon lists four kinds of content that are not allowed in search terms.
| Prohibited | Examples | Note |
|---|---|---|
| Brand names | Your own brand and other brands | Amazon already indexes your brand from the Brand field |
| ASINs | Any product ID starting with B0 | Yours or any other product’s |
| Temporary words | “new”, “latest”, “on sale” | They describe timing or a sale, not the product |
| Subjective words | “best”, “cheap”, “amazing” | They are claims, not descriptions |
Temporary words
Amazon prohibits words that describe a moment rather than the product:available nowbrand newcurrentdiscountedjust launchedlast chancelast minutelatestlimited timenewon salethis weekthis monththis yeartoday
Subjective words
It also prohibits claims that can’t be checked:amazingbestcheapcheapesteffectivefastestgood dealleastmostpopulartrending
Competitor brand names
Adding a competitor’s brand to catch their shoppers is tempting, and it breaks the rules. Your own brand is prohibited too, but for a different reason: Amazon already knows it, so it only wastes bytes.
Formatting rules that save bytes
These are Amazon’s best practices. Breaking them is not prohibited, but each one wastes bytes you could spend on a new term.
| Rule | Do | Don’t |
|---|---|---|
| Case | vitamin c serum | Vitamin C Serum |
| Separators | Spaces only | Commas, semicolons or pipes |
| Repetition | Each word once | “serum” in every phrase |
| Singular or plural | serum | serum serums |
| Filler words | Leave them out | a, the, for, with |
| Order | Any order | Repeating words to build phrases |
Amazon matches words in any order, so you don’t need to write “serum for dry skin” and “dry skin serum”. Write each word once and let Amazon combine them. Leave out these filler words:aanandbyforofthewith
What to put in instead
- Synonyms shoppers use for your product type.
- Abbreviations, such as “vit” for vitamin.
- Correct spelling variants, such as “ageing” and “aging”.
- Terms that are not already in your title and bullet points.
PrimeScale leaves out misspellings, because Amazon’s guidance asks for correct spelling variants, not typos.
Worked example: cleaning up a keyword dump
Here is the search terms field for a made-up vitamin C serum from a made-up brand, Mossleaf. Its title is “Mossleaf Vitamin C Face Serum with Hyaluronic Acid, 30 ml”. The field started as a list copied from a keyword spreadsheet.
The original, 296 bytes
Mossleaf Vitamin C Serum, best face serum for glowing skin, NEW vitamin c serum for women and men, serums for face, Glowbar serum alternative, B0EXAMPLE1, trending skincare, cheap serum, anti-ageing serum, brightening serum for dark spots, pigmentation serum, niacinamide serum, serum with hyaluronic acid for dry skin, ascorbic acid serum, glow serum for oily skin
The listing grader finds these problems in it:
- Search terms use 296 bytes. They must stay under 250, or none of them are indexed.
- Search terms include your brand name.
- Search terms include an ASIN.
- Search terms use temporary words Amazon prohibits: “new”.
- Search terms use subjective words Amazon prohibits: “best”, “cheap”, “trending”.
- Words repeated in search terms: “vitamin”, “c”, “serum”, “face”, “skin”, “acid”.
- Search terms include filler words: “for”, “and”, “with”.
- Search terms are separated with punctuation.
- Search terms use capital letters.
- Both singular and plural forms are used: “serum”.
It also names Glowbar, another brand, which is prohibited as well. Here is the clean-up, one step at a time, with the byte count after each step.
| Step | What changes | Bytes | Indexed? |
|---|---|---|---|
| The original | A keyword dump copied from a spreadsheet | 296 | No, none of it |
| Step 1 | Remove brand names, yours and other brands’, and the ASIN | 271 | No, none of it |
| Step 2 | Remove temporary and subjective words: “new”, “best”, “trending”, “cheap” | 251 | No, none of it |
| Step 3 | Lowercase, spaces only, each word once, no filler words, singular only, and no words already in the title | 98 | Yes |
| Step 4 | Use the space you saved on an abbreviation and a spelling variant: “vit” and “aging” | 106 | Yes |
Look at step 2. Every prohibited word is gone, and the field is still 251 bytes, so Amazon still indexes none of it. Removing banned words is not enough. The repetition has to go too.
Final, 106 bytes
vit ascorbic niacinamide brightening pigmentation dark spot anti ageing aging glow glowing skincare dry oily skin women men
The final field uses 106 of 249 bytes, and the grader finds no problems in it. It is shorter than the original, yet every word in it is indexed. There are 143 bytes left for more synonyms as you learn what shoppers search for.
A checklist before you upload
- Paste the field into the byte counter and confirm it is 249 bytes or fewer.
- Remove every brand name, yours included, and every ASIN.
- Remove temporary words such as “new” and subjective words such as “best”.
- Write in lowercase, separated by spaces, with each word once.
- Choose singular or plural, and drop filler words.
- Remove words that are already in your title and bullets, then use the space for synonyms and spelling variants.
- Run the whole listing through the Amazon listing grader. It checks search terms alongside your title, bullets and images.
Search terms work best alongside a clean title. Since July 2026 Amazon titles are limited to 75 characters, so some of the words you cut from titles may belong here. Read our guide to the 75-character title rule for that side of the listing.
Sources
The rules and fees in this guide come from these official pages. Practical advice is PrimeScale’s own. Marketplaces change their rules, so the seller dashboard remains the record of what applies to your account.
Frequently asked questions
What is the byte limit for Amazon backend search terms?
Amazon.in search terms must stay under 250 bytes, so 249 bytes is the most you can use. Spaces and punctuation do not count towards the limit.
What happens if my search terms are over 250 bytes?
Amazon indexes none of them. It does not index the first 249 bytes and drop the rest: the whole field stops working. That is why a long keyword dump can do more harm than a short, clean list.
Do spaces and commas count towards the 250 bytes?
No. Spaces and punctuation are not counted. You still don’t need commas: Amazon asks you to separate search terms with spaces, and it matches words in any order.
How many bytes is one character?
English letters a to z and the numbers 0 to 9 take 1 byte each. Accented letters such as é or ñ take 2 bytes each. That is why bytes and characters are not the same count.
Can I add competitor brand names to my search terms?
No. Amazon prohibits brand names in search terms, both other brands’ and your own. Amazon already indexes your brand from the Brand field. ASINs are prohibited too.
Which words are not allowed in Amazon search terms?
Brand names, ASINs, temporary words such as “available now”, “brand new”, “current”, “discounted” and “on sale”, and subjective words such as “amazing”, “best”, “cheap”, “cheapest” and “trending”. Filler words such as “a”, “the” and “with” are not prohibited, but they waste space.
Should I use singular and plural forms in search terms?
Use one or the other, not both. Pick the form shoppers use most for your product, and spend the bytes you save on a synonym or an abbreviation instead.
Should I repeat keywords from my title in search terms?
No. Use each word once, and add terms that are not already in your title and bullet points: synonyms, abbreviations and correct spelling variants shoppers use.