Snake Case Converter

Convert any text to snake_case format. Used for Python variables, database columns, file names, and API fields.

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What Is Snake Case?

Snake case (also written as snake_case) is a naming convention where words are separated by underscores and all letters are lowercase. For example, my_variable_name or user_first_name.

Snake Case vs Other Naming Conventions

Snake case: my_variable_name — used in Python, Ruby, databases
Camel case: myVariableName — used in JavaScript, Java
Kebab case: my-variable-name — used in URLs, CSS, HTML attributes
Pascal case: MyVariableName — used in C#, React components

What Is SCREAMING_SNAKE_CASE?

SCREAMING_SNAKE_CASE (also called upper snake case or CONSTANT_CASE) uses uppercase letters with underscores between words, e.g. MAX_RETRY_COUNT or API_BASE_URL. It is the standard for constants in most programming languages including Python, Java, C, C++, JavaScript, and Rust.

Format	Example	Usage
snake_case	`user_first_name`	Variables, functions
SCREAMING_SNAKE_CASE	`USER_FIRST_NAME`	Constants, env vars

How to Convert camelCase to snake_case

Converting camelCase to snake_case is one of the most common text transformations developers need. The algorithm inserts an underscore before each uppercase letter and then lowercases the entire string:

myVariableName → my_variable_name
getUserById → get_user_by_id
HTMLParser → html_parser

This is useful when migrating JavaScript or Java code to Python, converting JSON API responses to match Python conventions, or renaming database columns.

Snake Case in Python (PEP 8)

Python's official style guide, PEP 8, mandates snake_case for variables, functions, methods, and module names:

# Variables and functions: snake_case
user_count = 42
def calculate_total_price(items, tax_rate):
    ...

# Constants: SCREAMING_SNAKE_CASE
MAX_CONNECTIONS = 100
DEFAULT_TIMEOUT_SECONDS = 30

# Classes are the exception: PascalCase
class OrderProcessor:
    def get_pending_orders(self):  # methods: snake_case
        ...

Converting JavaScript-style names when porting code? See our guide on converting camelCase to snake_case in Python.

Snake Case for SQL Columns and Tables

Snake_case is the dominant convention for database naming because SQL is case-insensitive by default and many databases (PostgreSQL in particular) fold unquoted identifiers to lowercase:

CREATE TABLE customer_orders (
    order_id        BIGINT PRIMARY KEY,
    customer_id     BIGINT REFERENCES customers(customer_id),
    order_date      DATE NOT NULL,
    total_amount    NUMERIC(10, 2),
    shipping_status VARCHAR(20) DEFAULT 'pending'
);

Mixed-case column names like orderDate require quoting ("orderDate") in PostgreSQL forever after — snake_case avoids that trap entirely.

Where to Use Snake Case

Python variable and function names (PEP 8 standard)
Database table and column names (SQL convention)
PHP variable names in many legacy and WordPress codebases
Ruby method and variable names
API request and response field names
Configuration file keys
File naming in certain frameworks
Environment variable names (SCREAMING_SNAKE_CASE)
Rust variable and function names

Related Tools

Convert to hyphenated format with the Kebab Case Converter. Switch between JavaScript and Python naming with the CamelCase Converter. For all formats at once, try the Case Converter Online.