Key Differences Between VARCHAR And CHAR in MySQL 

Most database performance issues don’t start with complex queries or heavy traffic—they begin at the foundation: data type selection. One seemingly small decision—CHAR vs. VARCHAR—can dictate whether your database remains fast and efficient or bloated and sluggish as it scales. 

It’s a mistake even experienced developers make, and it’s easy to see why. At a glance, CHAR and VARCHAR look nearly identical, but their underlying mechanics differ significantly. To build a lean, high-performing MySQL database, you need to understand their key differences upfront and how they impact performance.  

Moreover, you must prioritize schema design early on to ensure long-term efficiency. Schema analysis and query optimization tools, like dbForge Studio for MySQL, help maintain optimal performance and eliminate inefficiencies before slowdowns creep in. 

This guide focuses on the difference between CHAR and VARCHAR in MySQL. We’ll highlight their ideal use cases, and how to choose the right type for lasting efficiency. Read on! 

Table of contents

• Overview of CHAR and VARCHAR
• What is CHAR in MySQL?
• What is VARCHAR in MySQL? 
• Key distinctions between CHAR and VARCHAR 
• When to use CHAR and VARCHAR 
• Advantages and disadvantages of CHAR vs VARCHAR 
• How dbForge Studio for MySQL simplifies CHAR and VARCHAR management  
• Conclusion
• FAQ

Overview of CHAR and VARCHAR 

While CHAR and VARCHAR store character strings, they use different storage mechanisms that impact how MySQL stores, retrieves, and manages text data over time. CHAR ensures speed and consistency by allocating the same space for every value, making indexing and retrieval predictable. On the other hand, VARCHAR prioritizes storage efficiency, adjusting to the text length while introducing overhead that may impact performance over time.  

Now, let’s look closer at CHAR vs VARCHAR in MySQL. 

What is CHAR in MySQL? 

CHAR is a fixed-length data type, meaning MySQL allocates the same space for every value, regardless of length. If a value is shorter than the defined length, MySQL pads it with spaces to maintain uniformity. This structure makes CHAR highly efficient for indexing and retrieval since MySQL knows precisely where each row begins and ends, streamlining performance. 

However, this efficiency comes at a cost—storage waste. For variable-length data, this results in wasted storage due to excessive padding. 

How CHAR optimizes read-heavy workloads 

CHAR excels in high-read workloads where speed and consistency matter most. Since every row is identical in size, MySQL doesn’t need to calculate row lengths on the fly, making range scans, sorting, and indexed lookups noticeably faster. 

This makes CHAR ideal for lookup tables, fixed-length identifiers (such as country codes or hashes), and frequently queried small datasets. 

Examples: how CHAR affects query results 

Let’s explore three key scenarios where CHAR can impact query behavior. 

1. Direct equality checks work as expected 

Imagine a table storing transaction codes, each expected to be exactly 10 characters long. 

CREATE TABLE transactions ( txn_code CHAR(10) );  
INSERT INTO transactions (txn_code) VALUES ('TXN123'); 

Since TXN123 is only six characters long, MySQL pads it with four spaces, storing it internally as ‘TXN123 ‘ to match the defined length of 10 characters. 

Query 

SELECT * FROM transactions WHERE txn_code = 'TXN123'; 

A match was found even though TXN123 is stored with extra spaces. When using the equality (=) operator, MySQL ignores trailing spaces in CHAR values during comparison. This makes direct lookups work as expected despite the extra spaces. 

2. Pattern matching with LIKE may not work as expected 

MySQL automatically pads CHAR(n) columns with trailing spaces to meet the fixed length. However, MySQL normally ignores these trailing spaces when using LIKE, so a value like ‘TXN123 ‘ (with spaces) should still match the pattern ‘TXN123%’. 

Query 

SELECT * FROM transactions WHERE txn_code LIKE 'TXN123%'; 

Expected Result: This query should return a match because MySQL ignores trailing spaces when using LIKE. 

Fix: Use CONCAT() 

Use a safer approach with CONCAT(). 

SELECT * FROM transactions WHERE txn_code LIKE CONCAT('TXN123', '%'); 

This approach ensures compatibility regardless of padding. 

3. Concatenation includes trailing spaces 

Another quirk of CHAR is that it preserves trailing spaces during string operations. This can cause unintended formatting issues. 

Query 

SELECT CONCAT(txn_code, '-CHECK') FROM transactions; 

Output 

TXN123-CHECK 

Problem: The spaces from CHAR(10) remain, pushing the “-CHECK” suffix farther than expected. Unlike VARCHAR, which trims excess space, CHAR retains its full allocated length—even when used in string functions. 

Solution: trim spaces before concatenation 

To avoid formatting issues, explicitly trim the value. 

SELECT CONCAT(TRIM(txn_code), '-CHECK') FROM transactions; 

Output (Corrected) 

TXN123-CHECK 

These traits make CHAR a solid choice for fixed-length fields but less ideal for text processing. However, VARCHAR is usually preferred when working with text operations, string manipulation, or external data formatting. Let’s take a closer look. 

What is VARCHAR in MySQL? 

VARCHAR is a flexible, variable-length data type designed for storing text with varying lengths. Unlike CHAR, which reserves a fixed space, VARCHAR dynamically adjusts its storage, using only the required space plus 1 or 2 bytes of metadata to track length. This optimizes storage efficiency in tables where values vary widely in size. 

How MySQL stores VARCHAR 

VARCHAR’s flexibility comes from its dynamic storage mechanism: 

• Strings ≤ 255 characters: MySQL stores 1 extra byte for length metadata. 
• Strings > 255 characters: MySQL stores 2 extra bytes for length metadata. 

VARCHAR dynamically adjusts storage, but in InnoDB, large values may be stored off-page, adding retrieval overhead. 

Examples: how VARCHAR behaves in updates 

Let’s explore how MySQL handles updates to VARCHAR fields and how to mitigate potential performance issues. 

1. Initial storage 

Let’s create a table with a VARCHAR column and insert a short text value: 

CREATE TABLE example_varchar ( description VARCHAR(50) );  
INSERT INTO example_varchar (description) VALUES ('Sample Text'); 

Here’s how MySQL stores this value: 

• ‘Sample Text’ is 11 bytes long (10 characters + 1 metadata byte). 
• The value fits neatly into the row, and MySQL efficiently stores it within the table’s data structure. 
• Retrieving the value works as expected. 

SELECT description FROM example_varchar; 

Output 

Sample Text 

At this stage, MySQL efficiently handles the storage, and queries remain fast and predictable. 

2. Updating to a longer value 

Now, let’s update the row to store a longer string. 

UPDATE example_varchar  
SET description = 'This is a much longer text than before'  
WHERE description = 'Sample Text'; 

Since the new value exceeds the original storage allocation, MySQL cannot store it in the same place. Instead, it must: 

1. Move the row to a new location that can accommodate the larger value. 
2. Leave behind a pointer in the original location to reference the new storage position. 
3. Increase read operations since MySQL must follow this pointer to retrieve the data. 

This process is known as row relocation and contributes to table fragmentation, which slows down queries over time. 

3. Checking for fragmentation issues 

To check for fragmentation caused by frequent updates, you can run the following code. 

SHOW TABLE STATUS LIKE 'example_varchar'; 

This will display the Data_free column, indicating how much unused space (fragmentation) exists in the table. If this number grows significantly, your queries will slow down because MySQL must scan across multiple locations to retrieve rows. 

4. Optimizing a fragmented table 

If you notice significant fragmentation, you can reorganize the table with: 

OPTIMIZE TABLE example_varchar; 

This forces MySQL to repack and defragment the table, improving performance by eliminating row relocation overhead. 

However, VARCHAR is not always better than CHAR—in update-heavy tables, VARCHAR values that increase in size may cause row relocation, leading to fragmentation and increased disk I/O. In InnoDB, large VARCHAR values may be stored off-page, which can slow down retrieval in read-heavy workloads. 

Key distinctions between CHAR and VARCHAR 

The table below highlights the difference between VARCHAR and CHAR in MySQL and when to use each. 

Aspect	CHAR	VARCHAR
Storage	Fixed-length: always reserves the defined space, padding shorter values with spaces. This makes row sizes consistent but wastes storage for shorter values.	Variable-length: stores only the actual characters plus 1–2 bytes of metadata. Saves space but causes fragmentation when rows expand.
Performance	Faster for indexing, sorting, and lookups because MySQL doesn’t need to calculate row lengths dynamically.	Slightly slower because MySQL must process variable lengths before retrieving values. Frequent updates can degrade performance over time due to row relocation.
Indexing Behavior	Works best in B-tree indexes where uniform row sizes improve efficiency. Range queries and sorting are faster.	Indexing is slightly less efficient due to variable row sizes. MySQL needs extra calculations before processing indexed queries.
Fragmentation Risk	None—fixed storage means rows are always aligned, preventing fragmentation.	High—in MyISAM, expanding VARCHAR values can fragment storage, while in InnoDB, large VARCHAR values may be stored off-page, affecting retrieval speed.
Best Use Cases	Fixed-length data like cryptographic hashes (SHA-256), country codes (ISO 3166), and logging tables, where uniform storage speeds up retrieval.	Variable-length text like names, descriptions, email addresses, and dynamic content, where storage efficiency is more important than retrieval speed.

Now, let’s explore the difference between CHAR and VARCHAR in MySQL with examples. 

Examples of CHAR vs. VARCHAR in performance 

Here are the instances where each one works best. 

Scenario 1: Storing fixed-length data (CHAR) 

Let’s say we store cryptographic hash values, which are always 32 characters long. 

CREATE TABLE user_hashes ( 
    hash CHAR(32) PRIMARY KEY 
); 

CHAR is the best choice because its fixed size makes indexing and lookups faster—MySQL doesn’t have to guess where each row starts. VARCHAR, on the other hand, just adds extra overhead without saving space, so there’s no real benefit in using it here. 

Scenario 2: Storing usernames (VARCHAR) 

Now, let’s store usernames, which vary in length. 

CREATE TABLE users ( 
    username VARCHAR(50) UNIQUE 
); 

Here, VARCHAR is the best choice since usernames range from short (e.g., ‘Joe’) to long (‘JonathanDoe123’), VARCHAR prevents unnecessary storage waste. However, if usernames are frequently updated and get longer, MySQL may have to move rows, causing fragmentation. 

Need to convert an existing CHAR column to VARCHAR or adjust its size? Follow this step-by-step guide on how to rename a column type in MySQL. 

Scenario 3: Sorting speed – CHAR vs. VARCHAR 

Test 1: Sorting on CHAR column 

CREATE TABLE test_char ( 
    product_code CHAR(11) PRIMARY KEY 
); 
 
INSERT INTO test_char VALUES  
('A123456789'), ('B234567890'), ('C345678901'); 
 
SELECT * FROM test_char ORDER BY product_code; 

Sorting is fast because CHAR ensures uniform row sizes. 

Test 2: Sorting on VARCHAR column 

CREATE TABLE test_varchar ( 
    product_code VARCHAR(10) PRIMARY KEY 
); 
 
INSERT INTO test_varchar VALUES  
('A123'), ('B234567890'), ('C345'); 
 
SELECT * FROM test_varchar ORDER BY product_code; 

Sorting takes longer because MySQL must calculate each row’s actual length before ordering results. 

When to use CHAR and VARCHAR 

Knowing when to use CHAR or VARCHAR comes down to data consistency, speed, and storage efficiency.  

Use CHAR when: 

• Data is always the same length – If every value fits a fixed size, like country codes (‘US’, ‘CA’) or cryptographic hashes (SHA-256), CHAR keeps things efficient and structured. 
• Speed matters more than storage – CHAR’s fixed size means MySQL doesn’t waste time checking lengths, making lookups, and sorting lightning-fast. 
• Predictable performance is needed – CHAR keeps row sizes consistent, making it ideal for high-read tables, reference data, and logs. No fragmentation, no surprises. 

Use VARCHAR when:

• Data varies in length – VARCHAR efficiently stores names, email addresses, descriptions, and user-generated text without unnecessary padding. 
• Storage needs optimization – VARCHAR only stores what’s needed, preventing the extra padding that CHAR forces on shorter values. 
• Frequent updates occur – If a VARCHAR value exceeds its allocated space, MySQL relocates the row, causing fragmentation and slowing down queries over time. 

Advantages and disadvantages of CHAR vs VARCHAR 

Both CHAR and VARCHAR have strengths and trade-offs. Choosing the right one depends on whether speed, storage, or flexibility matters most. Here’s a quick breakdown. 

CHAR: 

+Faster lookups – Fixed-size storage lets MySQL pinpoint rows instantly. 

+Best for uniform data – Ideal for IDs, hash values, and reference tables. 

– Massive storage waste – Storing a 10-char string in CHAR(255) wastes 96% of space. 

VARCHAR: 

+Space-efficient – Stores only actual text, cutting storage by up to 60%. 

+Ideal for dynamic data – Best for user input, descriptions, and variable-length text. 

-Performance trade-offs – Slower indexing due to metadata lookups and row relocation. 

How dbForge Studio for MySQL simplifies CHAR and VARCHAR management  

Choosing between CHAR and VARCHAR is just one piece of keeping a MySQL database efficient. Over time, performance can suffer due to fragmentation, slow queries, and inefficient indexing. dbForge Studio for MySQL helps developers avoid these issues by streamlining schema design, query execution, and data management, ensuring CHAR and VARCHAR fields are used effectively without slowdowns. 

Writing queries that run faster 

Clean, efficient queries are key to database performance. The SQL Editor in dbForge Studio highlights syntax, autocompletes commands, and suggests fixes in real time, reducing common errors like mismatched column names or missing commas. Execution plans provide insights into how MySQL processes CHAR and VARCHAR queries, making it easier to optimize sorting, filtering, and indexing. 

Enhancing query efficiency with advanced code completion 

dbForge Studio’s SQL Coding Assistance goes beyond mere column name suggestions by also indicating data types directly in the autocomplete list. This feature speeds up query writing by eliminating the need for developers to repeatedly refer to the schema for data type verification. Providing immediate data type insights boosts the development process speed and enhances coding accuracy and efficiency. 

Enhance text data handling with intuitive viewing and easy export options 

dbForge Studio’s Data Viewer enhances the way you handle text-heavy columns within large databases by displaying data in a reader-friendly format. This powerful tool not only facilitates the visualization of text data but also offers the convenience of saving this information as a file or copying it directly to the clipboard. These features significantly simplify data management tasks, providing a more efficient and user-friendly experience for database professionals. 

Keeping MySQL databases efficient 

Schema design and data type selection shape MySQL performance, but the right tools make optimization easier. dbForge Studio helps developers write better queries, manage data efficiently, and avoid performance bottlenecks. Whether working with CHAR for structured data or VARCHAR for flexible storage, it simplifies MySQL management for long-term efficiency. 

The takeaway 

Building a high-performing database starts with the right choices at every level. While selecting between CHAR and VARCHAR in MySQL is essential, proper optimization comes from well-structured schemas, efficient queries, and a scalable design. Every decision affects how smoothly your system handles growth and workload demands. 

FAQ 

What is the difference between CHAR and VARCHAR data types in MySQL? 

CHAR is a fixed-length data type, meaning it always reserves the same amount of space, regardless of the string length. This ensures predictable performance but can waste storage. VARCHAR, on the other hand, is variable-length, storing only the actual characters plus a small metadata overhead. CHAR is optimized for speed and consistency, while VARCHAR prioritizes storage efficiency and flexibility. 

Is it better to use CHAR or VARCHAR in MySQL? 

The choice depends on performance needs and storage considerations: 

• Use CHAR when storing fixed-size values like status codes, hash values, or short identifiers, where fast lookups and indexing matter more than storage savings. 

• Use VARCHAR for names, addresses, descriptions, or any text with unpredictable length, as it minimizes wasted space and scales better in dynamic applications. 

Why is VARCHAR preferred over CHAR? 

VARCHAR is often the default choice because it efficiently stores variable-length data without padding empty spaces like CHAR. In large-scale applications, this reduces storage consumption and improves overall database efficiency. However, CHAR still holds an advantage in indexing speed and query optimization for high-read workloads requiring consistent row sizes.