CONSTANT_CASE Converter

Turn any phrase into CONSTANT_CASE — free, instant, runs in your browser.

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What is CONSTANT_CASE?

CONSTANT_CASE writes every word in uppercase and joins them with underscores. It is also known as SCREAMING_SNAKE_CASE, MACRO_CASE or simply upper snake case.

CONSTANT_CASE examples

hello world example → HELLO_WORLD_EXAMPLE
max retry count → MAX_RETRY_COUNT
apiBaseUrl → API_BASE_URL

Where is CONSTANT_CASE used?

CONSTANT_CASE is the convention for constants in C, C++, Java, JavaScript and Python, for preprocessor macros, and above all for environment variables and configuration keys: DATABASE_URL, MAX_RETRY_COUNT, NODE_ENV. Files like .env and CI pipeline configs are full of it.

Why a special case for constants?

The loud style is deliberate: a fully capitalized name stands out in a file and signals "this value is fixed — do not reassign it". The convention goes back to C macros and has been kept by style guides ever since.

Common mistakes when converting case

Expecting editorial Title Case. The Title Case button capitalizes every word, including short ones: "the lord of the rings" becomes "The Lord Of The Rings". Style guides like AP and Chicago keep words such as "of", "the" and "and" lowercase, so adjust those by hand afterward.
Losing apostrophes. Word-based styles (Title Case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE) split on anything that is not a letter or digit, so "don't stop" turns into "Don T Stop" or "don_t_stop". Remove or restore apostrophes after converting.
Sentence case and proper nouns. Sentence case lowercases the whole text, then capitalizes only the first letter of each sentence, so "i visited NASA in june. it was fun." becomes "I visited nasa in june. It was fun." Re-capitalize names and acronyms yourself.

Pro tips

Rescue a Caps Lock accident with InVeRsE CaSe. Text typed as "hELLO wORLD" while Caps Lock inverted your Shift key flips back to "Hello World" in one click.
Acronyms split cleanly. "HTMLParser" converts to "htmlParser" with camelCase and "html_parser" with snake_case, because the word splitter detects where an acronym ends and the next word begins.
Only letters alternate. In aLtErNaTiNg CaSe, digits, spaces and punctuation stay in place and do not break the pattern: "abc 123 def" becomes "aBc 123 dEf".

Frequently asked questions

What other names does CONSTANT_CASE have?

It is most often called SCREAMING_SNAKE_CASE because it looks like snake_case shouting in all caps. Some communities also say MACRO_CASE or upper snake case.

What is the difference between CONSTANT_CASE and snake_case?

Both join words with underscores, but snake_case is all lowercase (max_retry_count) while CONSTANT_CASE is all uppercase (MAX_RETRY_COUNT). snake_case names variables; CONSTANT_CASE names values that never change.

Why are environment variables written in CONSTANT_CASE?

The habit comes from Unix shell and C conventions, where capitals marked macros and exported variables. The style stuck because it makes configuration values instantly recognizable in code and config files.

Other case converters

Or switch between every style in one place on the Case Converter homepage.