Hyphens vs. Underscores: Which is Better for Google Search?
📅 Published: May 10, 2026
Have you ever thought how Google see hyphens and underscores in our website? Or how do these symbols impact websites? Or what is the difference between hyphens and underscores when you rename a file on a website? If not, then this article is for you. In this article, I will discuss the difference between hyphens and underscores in Google search.
Hyphens and underscores are not just symbols or a matter of personal style. It has a difference that directly impacts your index ranking on Google search. While we might easily read both, the crawlers don't. Google bots read these symbols as distinct instructions. One symbol acts as a break between words, and another one may inadvertently glue them together, which as a result, makes your content harder to find.
Why Filenames Matter for SEO
Filenames are the medium through which Google understand the context of any file, like an image or a PDF document. Search engine bots don't have the ability to see any image or document visually, so they still heavily rely on text contained in the filename or surrounding text to identify what an image or document contains.
A filename like dbhw_32378.pdf provides no information when we look from the outside. In order to know about the PDF file, we have to open it and see inside. The same thing happens with search engine bots.
However, if a filename like red-cotton-shirt.jpg tells exactly what the subject is. This helps the bot to correctly index the file in the relevant search niche.
A significant chunk of web traffic comes from Google Images. Having your website with keyword-rich image filenames will increase the chance of getting your images in the Google Image section when users search for those specific terms.
Hyphens: The Gold Standard for Word Separation
As per research in the field of SEO, Google don't see hyphens ( - ) just as punctuation; they're a functional code that tells search engine bots exactly where one word ends and another begins. Crawlers see a hyphen as a space, like they see best-shoes-for-football.pdf as "best shoes for football" because Google identifies hyphens as a separator. This will make your content appear together in searches like "best shoes," "football shoes," and "shoes."
Other symbol like underscores or no separator cause words stick together into a single, unrecognizable string. Bots don't understand that a long string contain multiple words, they see as a single string. Using hyphens between words ensures that crawlers don't get confused.
Google officialy recommend that using hyphens is way better instead of underscores in URL because once uploaded on the web filenames become part of your URL structure. Also it is easy to read and understand quickly like best-shoes-for-football.pdf is signnificantly easier to read than bestshoesforfootball.pdf.
Underscores: The "Glue" that Binds Words Together
Underscores between words look good and cleaner from human point of view but in the crawlers words of search engine they look very differently than hyphens. Algorithm has view the underscrore as a connector not as a separator like hyphens. I try to explain this through an example Google see best_sunset_view.png as bestsunsetview.png.
Don't being overlooked because underscore between words are seen as a single unit, you may lose some partial match traffic like if your file is cheapest_cotton_pillows.pdf then Google may rank only for "cheapest cotton pillows" keyword but if someone searching specifically for cotton pillows then you may miss out.
Underscores are good for version control, internal organization, and coding work.
What Does Google Officially Recommend?
Google say that using hyphens help both users and crawlers to identify the context of the file. Underscores are often avoided because they are used in programming languages to denote concepts that need to be kept together. For better SEO and user experience, your default option for every new file you upload to renamefile.online should be hyphens.
Why Some Developers Still Use Underscores
In the programming world, languages like Python, C, and SQL, the use of spaces in variable and function names is strictly prohibited. Developers use snake_case (e.g., user_login_data) to make multi-word names readable without breaking the code. It is a possibility that some older systems can may misinterpret a hyphen as a minus sign. Underscores are "system-neutral" and almost never cause mathematical logic errors of this type.
In the early days of the web, spaces in file names were converted to %20 in URLs (for example, my file.jpg became my%20file.jpg), which was visually messy.
Should You Go Back and Rename Old Files?
As per me, If you are already have good ranking on google then you don't need to take the risk to change them. If you change the indexed file then if cause 404 not found error. Also, it cause link equity and as a result you lost aal the link juice you get earlier on your previous filename URL. In this case, you have to implement 301 redirects to you new filename URL.
If you decide to change your name, do it in small steps so you can monitor any unexpected drops in your search rankings.