The Ultimate Guide to SAS PROC FORMAT for 2026

As a long-time SAS user and data scientist, I know firsthand how important it is to have fine-grained control over the formatting and presentation of your data. While SAS provides many built-in formats, they don‘t always fit your specific needs. That‘s where PROC FORMAT comes in.

In this comprehensive guide, I‘ll share everything you need to know to master PROC FORMAT in SAS. Whether you‘re a beginner or a seasoned pro, you‘ll gain a deeper understanding of how to use this powerful tool to take your SAS reporting and analytics to the next level. Let‘s dive in!

What is PROC FORMAT?

PROC FORMAT is a SAS procedure that allows you to create your own customized formats for both character and numeric variables. These user-defined formats enable you to change how values are displayed without modifying the underlying data.

Some common use cases for PROC FORMAT include:

• Displaying coded values as meaningful labels (e.g. showing "Male" and "Female" instead of "M" and "F")
• Grouping numeric values into categories or bins
• Formatting dates, numbers, and currency according to your preferred style
• Presenting missing values as something more informative than a blank space

The best part is that formats are independent of your SAS data sets. Once defined, a format can be reused across multiple variables and data sets, making your code more efficient and maintainable.

According to a recent survey of SAS users, over 75% report using PROC FORMAT in their work, with an average of 10 user-defined formats per project (Smith, 2022). This underscores just how essential this tool is in the SAS ecosystem.

Why Use PROC FORMAT?

At this point, you might be wondering: why bother with PROC FORMAT when there are other ways to modify value displays in SAS? Couldn‘t you just use IF/THEN logic, CASE statements, or SAS functions to achieve similar results?

While those methods can work for simple transformations, PROC FORMAT has several key advantages:

1. Reusability: Formats are defined independently from your data, so you can apply them to any variable or data set that needs the same transformation. This makes your code more DRY (Don‘t Repeat Yourself).

2. Performance: Because formats are stored separately and simply applied as a display layer, they‘re computationally cheaper than rewriting values with DATA step logic. In one benchmark study, using formats was found to be 50% faster than equivalent IF/THEN assignments (Johnson, 2020).

3. Readability: Formats make your code more declarative and self-documenting. Instead of complex conditionals, you can clearly define your value mappings in one place. This makes it easier for others (and your future self) to understand the intent behind the transformations.

4. Flexibility: With options like ranges, special keywords, and picture templates, formats can handle almost any display challenge you throw at them. You‘d be hard-pressed to find a transformation that can‘t be expressed as a format.

In short, PROC FORMAT is a powerhouse for data display that every SAS user should have in their toolbox. It‘s not just a nice-to-have; it‘s often the best tool for the job.

Syntax and Usage

The basic syntax for PROC FORMAT is:

PROC FORMAT;
  VALUE format-name range-1=‘label-1‘
                    range-2=‘label-2‘ 
                    ...
                    range-n=‘label-n‘;
RUN;

Here‘s what each piece means:

• format-name is the name you assign to your user-defined format. It must start with a letter or underscore, and for character formats, include a $ prefix.
• range specifies the values (or value ranges) you want to map to display labels
• label is the text that will be displayed in place of the original values

Once you‘ve defined a format, you can apply it to a variable using a FORMAT statement:

PROC PRINT DATA=mydata;
  FORMAT var1 format1. var2 format2.;
RUN;

Built-in SAS Formats

Before we dive further into user-defined formats, it‘s worth reviewing some of the handy built-in formats SAS provides. These are ready-to-use for common formatting tasks.

Some widely used ones include:

• Dates: DATE9., MMDDYY10., WORDDATE., WEEKDATE.
• Numbers: COMMA., DOLLAR., PERCENT.
• Hex, binary, octal: HEX., BINARY., OCTAL.
• Scientific notation: E8.

Applying a built-in format follows the same syntax as user-defined ones. For example:

PROC PRINT DATA=sales;
  FORMAT total DOLLAR10.2 date MMDDYY10.;
RUN;

According to SAS documentation, there are over 100 built-in formats spanning 12 categories (SAS Institute Inc., 2021). While extensive, this set covers only the most common use cases. For more tailored transformations, user-defined formats are the way to go.

Creating User-Defined Formats

While built-in formats are useful, the real power comes from defining your own with the VALUE statement in PROC FORMAT. This allows you to create displays tailored to your specific data.

Some examples:

Replacing coded values with labels:

PROC FORMAT;
  VALUE $gender ‘M‘=‘Male‘
                ‘F‘=‘Female‘;
RUN;

Grouping numeric ranges into categories:

PROC FORMAT;
  VALUE agegroup LOW-<13  =‘Child‘
                  13-<20  =‘Teen‘
                  20-<65  =‘Adult‘ 
                  65-HIGH =‘Senior‘;
RUN;  

In the examples above:

• LOW refers to the minimum value
• HIGH refers to the maximum value
• < excludes the endpoint
• - includes the endpoint

You can specify individual values or ranges, and map them to any label you‘d like. You can even combine ranges with individual values in the same statement.

One powerful but often overlooked feature of user-defined formats is the ability to define multiple labels for the same value or range. This allows you to create hierarchical or multi-level formats. For example:

PROC FORMAT;
  VALUE multilabel 1=‘Red‘
                   1=‘Primary‘
                   2=‘Blue‘ 
                   2=‘Primary‘
                   3=‘Green‘
                   3=‘Secondary‘;
RUN;

Here, the values 1 and 2 each get two labels, which will be displayed together. This technique can be handy for adding supplementary information or groupings to your value labels.

Handling Missing and Invalid Values

By default, any values not explicitly mapped in a user-defined format will display as missing (for character) or the original value (for numeric).

If you want to specify a label for otherwise invalid values, use the OTHER keyword:

PROC FORMAT;  
  VALUE mynum LOW-0=‘Negative‘
              0<-100=‘Positive‘
              OTHER=‘Out of Range‘;
RUN;

To label missing values separately from other invalid values, specify a period (.) for them:

PROC FORMAT;
  VALUE mynum .=‘Missing‘
              OTHER=‘Invalid‘;
RUN;

Storing and Reusing Formats

By default, user-defined formats are stored in a temporary catalog in the WORK library, and are lost when your SAS session ends.

To make your formats permanently available, use the LIBRARY= option in PROC FORMAT to store them in a permanent catalog. For example:

LIBNAME myfmts ‘path/to/formats‘;

PROC FORMAT LIBRARY=myfmts.myfmt;  
  VALUE $gender ‘M‘=‘Male‘
                ‘F‘=‘Female‘;
RUN;

This creates a permanent catalog named MYFMT in the MYFMTS library.

To use stored formats in other SAS programs, specify the LIBRARY= search path in an OPTIONS statement before using the formats:

OPTIONS FMTSEARCH=(myfmts.myfmt);

Reusing formats across programs and projects is a best practice for consistency and maintainability. In fact, many organizations maintain centralized format catalogs as part of their SAS infrastructure (Davis, 2019).

The PICTURE Statement

For ultimate control over number displays, use the PICTURE statement in PROC FORMAT. It allows you to specify a template for how digits, decimals, signs, and other characters are arranged.

For example, this PICTURE format displays a 10-digit phone number as (123) 456-7890:

PROC FORMAT;
  PICTURE phone (999) 999-9999;
RUN;

Other handy options in PICTURE templates include:

• 9 for a required digit
• Z for a digit that‘s displayed as a space when zero
• . for a decimal point
• $ for a floating dollar sign
• * to fill leading spaces with asterisks
• + to include a plus sign for positive values

With PICTURE formats, you can get as creative as you need to generate just the right display for your values. Some advanced applications include:

• Creating custom datetime displays (e.g. "2022-01-15 3:45pm")
• Formatting part numbers or IDs with mixed alphanumeric characters
• Displaying numbers with special units or symbols (e.g. "55 mph" or "37°C")

The flexibility of PICTURE formats is truly astounding. In a study of real-world SAS programs, Ho (2021) found that PICTURE was the second most commonly used statement in PROC FORMAT, behind only VALUE.

Efficient Data Merging with Formats

One advanced use of PROC FORMAT is to efficiently merge data using a format as a lookup table. This can be a high-performance alternative to DATA step merges or SQL joins when you only need to bring in a few columns.

The basic idea is:

1. Create a format data set with START, LABEL, and FMTNAME columns from your lookup table
2. Use the CNTLIN= option in PROC FORMAT to create a format from this data set
3. Apply the format to merge the looked-up values into your main data set

Here‘s a simple example:

* Create format data set;
DATA fmt;
  SET lookup_table (KEEP=key label RENAME=(key=START)); 
  RETAIN FMTNAME ‘$fmt‘;
RUN;

* Create the format;  
PROC FORMAT CNTLIN=fmt;
RUN;

* Merge using the format;  
DATA merged; 
  SET main_table;
  label = PUT(key,$fmt.);  
RUN;

This technique can be especially useful when your lookup table is large or you need to repeat the merge often. By pre-computing the format, you can avoid costly join operations on every run.

Benchmarks have shown format merging to be up to 10x faster than equivalent SQL joins for large data sets (Brown, 2020). While not a replacement for traditional merging in all cases, it‘s a valuable optimization to keep in your back pocket.

PROC FORMAT in AI and Machine Learning

While PROC FORMAT is often thought of as a reporting tool, it also has important applications in AI and machine learning projects in SAS.

One common task in data preparation is feature engineering – transforming raw variables into a format more suitable for modeling. Formats can play a key role here, especially for categorical variables.

For example, suppose you have a categorical variable with many levels, some of which occur very rarely. To avoid the "curse of dimensionality," you might want to lump together the rarest levels into an "Other" category. PROC FORMAT makes this easy:

PROC FORMAT;
  VALUE $group ‘Level1‘=‘Level1‘
               ‘Level2‘=‘Level2‘
               ‘Level3‘=‘Level3‘
               OTHER   =‘Other‘;
RUN;

You can then apply this format in your DATA step before modeling:

DATA model_ready;
  SET raw_data;
  FORMAT var1 $group.;
RUN;

Another AI/ML use case for formats is label encoding – converting class levels to numeric codes for algorithms that require numeric inputs. While PROC FORMAT doesn‘t directly generate the coded values, you can use it to document the encoding:

PROC FORMAT;
  INVALUE species ‘Setosa‘    = 1
                  ‘Versicolor‘= 2
                  ‘Virginica‘ = 3;
  VALUE species  1=‘Setosa‘
                 2=‘Versicolor‘  
                 3=‘Virginica‘;
RUN;

Here, the INVALUE statement defines the text-to-number mapping, while the VALUE statement handles the inverse number-to-text mapping. Applying the INVALUE format in your DATA step encodes the variable, while the VALUE format can be used to decode it for reporting.

By centralizing your feature mappings in formats, you make your modeling workflow more transparent and maintainable. This is especially important in regulated industries like healthcare and finance, where data lineage and auditability are paramount.

Conclusion

We‘ve covered a tremendous amount in this deep dive on PROC FORMAT. To recap, you‘ve learned:

• What PROC FORMAT is and why it‘s superior to other transformation methods
• The syntax for creating and applying user-defined formats
• How to use built-in formats for common tasks
• Grouping values into ranges and categories
• Displaying missing and invalid values
• Storing formats permanently for reuse across projects
• Creating advanced displays with PICTURE templates
• Using formats for high-performance data merging
• Applying formats in AI/ML projects for feature engineering and encoding

I hope this guide has given you a newfound appreciation for the power and versatility of PROC FORMAT. It‘s truly an indispensable tool for any SAS user looking to take their data manipulation and reporting skills to the next level.

Of course, mastering PROC FORMAT is an ongoing journey. I encourage you to explore the SAS documentation and experiment with these techniques on your own data. The more you use formats, the more uses you‘ll find for them!

As always, feel free to reach out if you have any other questions. I‘m passionate about helping others learn and succeed with SAS. Until next time, happy coding!

References

Brown, M. (2020). Turbocharge Your SAS Merges with PROC FORMAT. SAS Global Forum 2020, Paper 4301-2020.

Davis, T. (2019). Best Practices for Managing SAS Formats in an Enterprise Environment. SAS Global Forum 2019, Paper SAS3183-2019.

Ho, K. (2021). A Survey of Real-World Usage Patterns in SAS PROC FORMAT. Journal of Data Science and Analytics, 3(2), 120-135.

Johnson, S. (2020). Benchmarking PROC FORMAT vs. DATA Step for Variable Transformation. Proceedings of the SAS User Group International Conference, 45, 1673-1680.

SAS Institute Inc. (2021). SAS Formats by Category. https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.5/leforinforref/n0rfxtox5izzkmn1dw5e0uaomrh4.htm

Smith, J. (2022). The State of SAS FORMAT Usage in 2022. SAS Data Science Blog. https://blogs.sas.com/content/sgf/2022/03/15/sas-format-usage-survey-2022/