Amazon backend Search Terms: rules and byte limit

Search Terms sit on the Keywords tab of a listing in Seller Central. Amazon’s notices call them generic keywords. Shoppers don’t see them on the product page.

Amazon’s own tips say to use the field for:

• synonyms;
• abbreviations and other names for the product;
• spelling variations;
• words buyers search that don’t fit in the title or bullets.

Amazon set the limit in a 2017 notice: “less than 200 bytes in India, 500 bytes in Japan and 250 bytes in every other marketplace except China.” It covers all your generic keyword fields together, and “whole entry will be rejected upon exceeding limit.”

“Less than 250” means 249 at most. Sources round it in different ways:

• The 2017 notice says less than 250 bytes, and less than 200 in India.
• An Amazon staff tip says “limited to 250 bytes”.
• Another Amazon post says “250 characters”.
• A seller in the forums reports that a field of 250 bytes or more gets nothing indexed.

We follow the notice. Shopperwords uses 249 bytes, and 199 in India. Japan’s notice says under 500 bytes; Shopperwords still uses 249 there to be safe.

A byte is a unit of storage, not a letter. Amazon’s notice says letters and digits (a–z, 0–9) take 1 byte each, and other characters take 2 or more: “ä (2 bytes), £ (2 bytes), € (3 bytes)”.

Those examples match UTF-8, the encoding most of the web uses. So:

• “yoga mat” is 8 characters and 8 bytes.
• “für” is 3 characters and 4 bytes.
• “ヨガマット” is 5 characters and 15 bytes.

A character counter will tell you a German, French or Japanese field fits when it doesn’t. Count bytes.

Amazon’s notice says “spaces and punctuation (“;” “,” “.”) do not contribute to the length limit, but words should be space-separated.” Put one space between words. Leave out commas and semicolons.

Most checkers count spaces anyway, and so do we. That errs on the safe side: a field that fits with its spaces counted also fits without them. In the example below, the spaces add 18 bytes.

Amazon’s guidance lists these. Each one wastes bytes or breaks a rule.

• Words already in your title, brand or other fields. Amazon says repeating them doesn’t help.
• Repeats. Put each word in once.
• Both singular and plural. Amazon says to use either one.
• Filler words like a, an, and, by, for, of, the and with.
• Misspellings. Amazon handles common ones itself. Spelling variations are fine.
• Brand names, yours or anyone else’s.
• ASINs.
• Temporary claims like “new” or “on sale now”.
• Subjective claims like “best”, “cheapest” or “amazing”.
• Profanity or abusive terms.

Amazon warns that banned keywords “may result in ASIN suppression and action against your account.”

Say your title is “Thick Yoga Mat Non Slip, 1/2 Inch Exercise Mat for Home Workout”. The words below come from Amazon’s suggestions around “yoga mat”, minus the title’s words, brands, filler and words that don’t describe this mat.

• Left out as title words: yoga, mat, thick, non, slip, exercise, home, workout.
• Left out as brands: manduka, gaiam, alo.
• Left out as subjective: best, cheap.
• Left out as other products: towel, cleaner, wall mount.

That leaves 128 bytes. Fill them from your other seeds, like “exercise mat” or “pilates mat”.

Paste your field into the free Search Terms checker to count its bytes before you save it. To find the words in the first place, see how to find Amazon keywords.

Shopperwords Pro has a Search Terms builder. It fills the field from the keywords on screen, best words by estimated volume first, within your store’s byte limit. It leaves out your title’s words, filler and repeats, and counts a plural as its singular. See pricing.