Domain Name Requirements: Can Domain Names Have Numbers and Symbols?

Every day, thousands domains are registered online, yet the guidelines and conventions surrounding domain name registration are often overlooked.

Can domain names have numbers? How about underscores or symbols? How come there are occasionally domain names with periods? We will be going over these questions and highlighting what you should consider when registering your domains.

 

Valid Characters in Domain Names: What's Allowed

When registering a domain name, it's important to understand what characters you can and cannot use.

Domain names have specific rules regarding which characters are permitted, with only letters, numbers, and hyphens being allowed. Let's explore what's allowed and how to effectively use these permitted characters in your domain name.

 

Rules at a Glance

✅ Allowed: Letters (a–z), digits (0–9), and hyphens (-). Case-insensitive.

🚫 Not allowed: Spaces, underscores, or special symbols.

🔢 Lengths: Up to 63 characters per label; approximately 253 total for the full domain (RFC 1035, RFC 1123).

 

Domain Numbers: Using Numbers in Domain Names

Domain names can have numbers. Despite the ability to add them, numbers in domains are typically avoided as they can have a negative effect on how intuitive the domain name is to understand.

Having a name with numbers included may be a barrier for users accessing your website due to not understanding whether the domain name uses a digit character or a written word of a number (for example, “4” versus “four”).

Exceptions to this include terms where the number character is commonly used, such as B2B or MP4, which are understood and frequently written in those specific ways.

If you wanted to register a domain that has a more unclear numerical use, there is the option to register both versions of a domain (one using the word of the number and the other including just the single-digit character) and redirect the incorrect domain name to the proper domain name. Just ensure that both domain names are available before registering either domain.

 

Example: If your business name is “Metallic Seven”, you could try to register both metallicseven.com and metallic7.com and redirect the latter to the former. This will minimize potential lost traffic opportunities.

 

Hyphens in Domain Names: Rules and Best Practices

Domains with hyphens are allowed, though they are rarer than including numbers. Much like how domain names can have numbers, domain names can have hyphens but they often have downsides.

They are uncommon and this is due to adding complexity and potentially a hurdle for your audience to land on your website.

 

Example: “Saying “One for All” and “One-for-All” out loud are two different things, and you are bound to lose some of your audience on their journey to find your website if hyphens are included. In almost all scenarios, it is best to forgo using hyphens and search for alternatives.”

 

What Characters Are Not Allowed in Domain Names

While domain names can include letters, numbers, and hyphens, many other characters and formatting options are strictly prohibited by the Domain Name System (DNS).

Understanding these restrictions is crucial to avoid confusion when registering your domain. Here are the key elements that cannot be used in domain names and why they're not permitted:

 

Understanding Periods in Domain Names

Periods cannot be used when registering a domain name. However, periods are included in websites that utilize subdomains, which is why some webpages have the following URL structure:

‘subdomain.domainname.com’.

Subdomains are used to contain content that is separate from the main website but is still under the main website’s hosting.

 

Example: ‘blog.domainname.com’

blog. is a common subdomain for a website blog. The domain name does not include a period.

 

Special Characters and Symbols

Numbers and hyphens are the only symbols allowed in your domain name. Spaces and underscores are not allowed, and the symbols listed below are also not allowed.

❌ Not Allowed Characters:

! @ # $ % ^ & * ( ) ; : , ? / \ = + < >

 

Do Domain Names Have to Be Lowercase?

Domain names are case insensitive, which means using upper and lower case characters is irrelevant. Typing in a domain name in all capital letters will take you to the same domain as typing in all lowercase.

You cannot register a domain that uses capital letters because of this, they are considered the same characters.

 

Internationalized Domain Names (IDNs)

While most domain names use standard Latin characters (a–z, 0–9, and hyphens), Internationalized Domain Names (IDNs) allow the use of characters from non-Latin scripts such as Chinese, Arabic, Cyrillic, or accented Latin letters.

These domains make the internet more accessible by letting users register names in their native languages or alphabets.

For example, 例子.com or münchen.de are valid IDNs, though they are stored in the DNS as encoded “Punycode” versions (beginning with xn–).

If your brand or audience uses another language, registering an IDN can help improve recognition and local relevance.

 

Essential Domain Name Requirements to Keep in Mind

Beyond the basic rules of what characters are allowed or prohibited in domain names, there are several technical specifications and practical limitations you should consider.

These factors affect how your domain functions, how easily users can find and remember it, and ultimately how successful your online presence will be:

 

Domain Name Length Requirements and Formatting Rules

Each label (the part between dots) can contain up to 63 characters, and the total fully qualified domain name (FQDN) can be up to approximately 253 characters in length. The 63 characters do not include what is referred to as the ‘protocol identifier’ (https://) or the domain extension (such as .com or .org).

This is purely the domain name (sometimes referred to as the ‘label’) between the two. Avoid having a domain name anywhere near this maximum length as it will become more challenging for users to find and navigate to your site.

 

Additional Considerations for Domain Name Requirements

When selecting the perfect domain name for your website, there are strategic elements that go beyond the technical rules.

These considerations impact user experience, brand perception, and the overall effectiveness of your online presence. Here are additional factors to evaluate when choosing your domain name:

 

Syntax & Structure

Domain Name Length: Shorter domain names have the advantage of improving accessibility by typically being easier to type and remember.

Name Difficulty: Simpler domain names are often the best choice. They are much easier for users to type in, remember, and rely less on your audience’s spelling ability. 

Example: A language-learning website using ‘wordpronunciation.com’ will be harder for users to get to due to using a more complex word to spell.

 

Domain Name Best Practices

Avoid Branded Terms: Using trademarked or existing branded terms in a domain name can get you labelled as a cybersquatter, which is someone who registers a domain with a trademark to profit from or for malicious use.

Brandable vs. Description: Choosing between a new brand name idea or a descriptive name for your domain is an important decision as it can have a drastic effect on your domain’s discoverability. Be sure to read our blog going over the ins and outs of brandable versus descriptive domain names.

Domain Extensions and TLD Requirements

When selecting a domain, the extension you choose (.com, .org, .net) plays an important role in how users perceive your website. While .com remains the most recognized extension, other TLDs may better suit specific purposes or industries. Domain extensions can also affect memorability and user trust, so consider your audience when selecting your TLD.

With this knowledge, you will be better equipped when registering a domain name by knowing what is and isn’t allowed, along with understanding how you can use characters such as numbers in a domain name if required. Knowing these guidelines can be useful, whether you are registering a domain for your business or even evaluating domains to invest in. 

Got an idea for registering a domain? Use Dynadot’s domain name search to register your domain in minutes.

 

FAQs

 

Can domain names start with a number?

Yes, domain names can start with a number. While technically allowed, starting your domain with a number may make it less intuitive and harder to remember. Search engines treat domains that start with numbers the same as any other domain, but from a branding perspective, it might be less ideal than starting with a letter.

 

What's the maximum length for a domain name?

Domain names can be up to 63 characters long (not including the extension like .com). However, shorter domains (ideally under 15 characters) are generally more effective as they're easier to type, remember, and less prone to typing errors.

 

Can I use underscores in my domain name?

No, underscores (_) are not allowed. Only letters, numbers, and hyphens are permitted. If you want to separate words in your domain, your only option is to use hyphens, though as mentioned earlier, these come with their own disadvantages.

 

Can I use both numbers and hyphens in the same domain?

Yes, you can use both numbers and hyphens in the same domain name. For example, "web-design-123.com" would be valid. However, combining both may create additional complexity for users trying to remember or type your domain, so consider whether the specific combination is worth potential usability challenges.

 

Can emojis be used in domain names?

No, standard emojis cannot be used in traditional domain names. Some domain registrars offer what appear to be emoji domains, but these are Punycode translations (starting with "xn--") that display as emojis in some browsers but are not actual emoji characters in the DNS system.