ATF Fingerprint File Formats Guide: EFT, NIST, EFTS, EBTS Explained

Introduction

If you are working with digital fingerprints for ATF NFA applications, you have likely encountered confusing acronyms: EFT, NIST, EFTS, EBTS, WSQ. These refer to file formats and standards used to store and transmit biometric data.

The good news: all these formats are based on the same underlying standard and can be converted between each other. Understanding the basics helps you work with files from different sources and troubleshoot issues.

This guide explains each format, how they relate, and what ATF actually accepts.

The ANSI/NIST-ITL Standard

All major fingerprint file formats in the US are based on ANSI/NIST-ITL (American National Standards Institute / National Institute of Standards and Technology - Information Technology Laboratory).

What Is ANSI/NIST-ITL?

ANSI/NIST-ITL is a data format standard for exchanging biometric information (fingerprints, facial images, iris scans, etc.) between systems. It defines:

• File structure: How data is organized into records
• Record types: Different types for different data (fingerprints, photos, text)
• Field definitions: What information goes where
• Image formats: How fingerprint images are stored

Why One Standard?

Before ANSI/NIST-ITL, every agency had its own format. Sharing fingerprints between FBI, state police, and other agencies was difficult. The standard ensures interoperability—fingerprints captured in Florida can be processed in California or by the FBI.

Standard Versions

The standard has evolved over time:

• ANSI/NIST-ITL 1-2000: Older version, still in use
• ANSI/NIST-ITL 1-2007: Added Type-14 (flat fingerprints)
• ANSI/NIST-ITL 1-2011: Current version, enhanced features

Most NFA-related files use features from the 2007 or 2011 versions.

Format Overview Table

All formats share the same core structure. The differences are in metadata fields, transaction codes, and agency-specific requirements.

EFT Format (ATF)

EFT (Electronic Fingerprint Transmission) is ATF's specific implementation of ANSI/NIST-ITL for eForms submissions.

ATF EFT Requirements

• File size: Maximum 12MB
• Fingerprint type: Ten-print (all 10 fingers)
• Image format: WSQ compressed
• Resolution: 500 DPI minimum
• Record types: Type-1 (transaction), Type-2 (descriptive), Type-4 or Type-14 (fingerprints)

What Makes a File "ATF-Compliant"?

An ATF-compliant EFT file has:

1. Correct transaction type codes for ATF
2. Required personal information fields populated
3. All 10 fingerprints present (or properly marked if missing)
4. WSQ compression within acceptable parameters
5. Total file size under 12MB

File Extension

ATF EFT files typically use the .eft extension, though .nst and others may also work.

EFTS Format (FBI)

EFTS (Electronic Fingerprint Transmission Specification) is the FBI's implementation of ANSI/NIST-ITL.

EFTS Characteristics

• Used for: FBI background checks, IAFIS/NGI submissions
• Transaction types: Different codes than ATF (criminal, civil, etc.)
• Additional data: May include photos, palm prints
• File sizes: Can be larger than ATF allows

Converting EFTS to ATF EFT

EFTS files can be converted to ATF format by:

1. Extracting fingerprint images
2. Reformatting transaction/metadata fields
3. Removing unnecessary records (photos, palms)
4. Compressing to meet 12MB limit

SlapEFT handles this conversion automatically.

EBTS Format (DoD)

EBTS (Electronic Biometric Transmission Specification) is the Department of Defense's implementation.

EBTS Characteristics

• Used for: Military enlistment, security clearances, ABIS
• Extended biometrics: Often includes iris, facial recognition data
• Higher resolution: May use 1000 DPI fingerprints
• Larger files: Typically bigger than FBI or ATF files

Converting EBTS to ATF EFT

EBTS files require more processing:

1. Extract fingerprint records only
2. Downsample if resolution exceeds requirements
3. Convert transaction codes
4. Recompress to meet size limits

SlapEFT handles EBTS conversion automatically.

See our detailed guide: EBTS vs EFTS: Understanding the Formats

WSQ Compression

WSQ (Wavelet Scalar Quantization) is the fingerprint image compression standard used by all US government fingerprint systems.

Why WSQ?

Standard image formats (JPEG, PNG) are not ideal for fingerprints:

• JPEG creates artifacts that can obscure ridge detail
• PNG files are too large for practical transmission
• WSQ was specifically designed for fingerprint compression

WSQ Compression Ratios

WSQ allows variable compression. Common ratios:

• 15:1: High quality, larger files
• 20:1: Good balance (commonly used)
• 25:1: Smaller files, still acceptable quality

WSQ and File Size

ATF's 12MB limit means WSQ compression settings matter. If files are too large:

• Increase compression ratio (may reduce quality)
• Ensure no unnecessary records in file
• SlapEFT automatically optimizes compression

See our guide: Fingerprint File Too Large for ATF?

Type-4 vs Type-14 Records

Within NIST files, fingerprints can be stored in different record types:

Type-4: High-Resolution Grayscale (Rolled)

• Capture method: Rolled fingerprints (finger rolled across scanner)
• Coverage: Full nail-to-nail fingerprint
• Traditional use: Criminal booking, detailed analysis
• ATF acceptance: YES

Type-14: Variable-Resolution Latent/Flat

• Capture method: Flat (slap) fingerprints
• Coverage: Central portion of fingerprint
• Modern use: LiveScan, quick capture
• ATF acceptance: YES

Which Is Better for NFA?

Both work for ATF submissions. Type-14 (flat prints) are more common from modern LiveScan equipment. Type-4 (rolled prints) provide more detail but require more careful capture technique.

See our detailed guide: Type-14 vs Type-4: Which Format for ATF?

File Extensions Guide

Fingerprint files use various extensions. Here is what they mean:

Important Note

File extensions do not always accurately reflect contents. Some vendors use non-standard extensions. If your file does not work, try uploading anyway—SlapEFT examines file contents, not just extensions.

Converting Between Formats

What Conversion Involves

Converting a fingerprint file to ATF format typically involves:

1. Parsing: Reading the source file structure
2. Extracting: Pulling out fingerprint images and required metadata
3. Transforming: Adjusting field formats and codes for ATF
4. Compressing: Optimizing WSQ to meet size limits
5. Rebuilding: Creating new file with ATF-compliant structure

DIY Conversion (Technical)

If you are technically inclined, tools exist:

• NBIS: NIST Biometric Image Software (command-line)
• OpenEFT: Open-source converter (requires Docker)
• EFT Suite: Another open-source option (requires Docker)

These require technical setup and troubleshooting.

Easy Conversion (SlapEFT)

For non-technical users:

1. Go to SlapEFT NIST to ATF Converter
2. Upload your file (any supported format)
3. System automatically handles all conversion steps
4. Pay $10 and download ATF-compliant EFT

Frequently Asked Questions

Does ATF accept NIST files directly?

ATF eForms accepts files that meet their specific EFT requirements. A generic NIST file may or may not work depending on its structure. Converting through SlapEFT ensures compatibility.

What if my file has no extension?

Some systems output files without extensions. Try adding .eft or .nst and uploading to SlapEFT. The converter examines file contents, not just the filename.

Can I convert image files (JPEG, PNG) to EFT?

Standard image files are not NIST format. However, if you have a scanned FD-258 card as an image, you can use SlapEFT's card conversion instead.

Why does my file show different fingerprint counts?

Some files include multiple captures of the same fingers (for quality selection) or include palm prints. ATF only needs 10 fingerprints—conversion extracts what is needed.

Is there quality loss during conversion?

Conversion preserves fingerprint image quality. If recompression is needed for file size, it is done conservatively. The result is still high-quality biometric data.

Can I view my fingerprint file before converting?

Free NIST viewers exist (Universal Latent Workstation, NIST software). However, they can be complex to use. SlapEFT shows a preview during conversion.

What happens to extra data in my file (photos, palm prints)?

SlapEFT extracts only the fingerprint data needed for ATF. Other biometrics are not included in the output file.

Conclusion

Understanding fingerprint file formats helps you work with files from different sources:

• All formats are based on ANSI/NIST-ITL — they are fundamentally compatible
• EFT is ATF's specific format — other formats need conversion
• EFTS (FBI) and EBTS (DoD) — can be converted with proper tools
• WSQ compression — standard for all fingerprint images
• File extensions — helpful hints but not always accurate

Whether you have fingerprints from FBI background checks, military service, state agencies, or LiveScan services, they can all be converted to ATF-compliant format for your NFA applications.

Have a fingerprint file to convert? Convert it now →