EZtol

EZtol is a specialized engineering tool for 1D tolerance stack-up analysis, designed to help engineers evaluate how dimensional variation accumulates across mechanical assemblies. Developed by Sigmetrix, it focuses on linear tolerance chains, making it a practical solution for early-stage design validation and production risk assessment.

At its core, EZtol allows engineers to model a chain of dimensions and tolerances, then calculate how variation propagates through the system. This is critical for understanding fit, clearance, and interference conditions in assemblies such as shafts, housings, fasteners, and aligned components.

Unlike full 3D tolerance analysis platforms, EZtol operates in a simplified 1D environment, which makes it significantly faster to set up and easier to interpret. Engineers can define worst-case scenarios, statistical distributions, and sensitivity contributions to identify which dimensions are driving variation.

The software supports both worst-case analysis and statistical methods including RSS and Monte Carlo-style approaches, allowing teams to balance conservative design with realistic manufacturing variation. This makes it particularly useful during early design stages, tolerance optimization, and cost reduction efforts.

EZtol is commonly used in industries such as automotive, aerospace, and industrial equipment, where tolerance stack-ups directly impact product performance, manufacturability, and quality.

Key Features

• 1D tolerance stack-up analysis with direct CAD model import from CATIA, SolidWorks, and Siemens NX
• PMI reading for SolidWorks models, allowing part tolerance annotations to be used directly in stack-up definitions
• Worst-case, RSS, and statistical analysis methods with results reported as Cpk, Sigma, DPMO, or yield percentage
• Multiple simultaneous stack-up analyses on the same assembly with a unified summary table for compliance review
• Automatic update of all analyses when shared tolerance values change, eliminating manual synchronization across analysis tabs
• 3D effect detection with algorithms that identify when 3D geometric relationships are likely to invalidate a 1D linear stack-up assumption
• Graphical visualization of tolerance contribution by part and dimension, highlighting the highest contributors to assembly variation
• Standalone application mode for users without direct access to the originating CAD environment
• Integration with the broader Sigmetrix portfolio alongside CETOL 6σ, GD&T Advisor, and VariSight

Best For

Mechanical design engineers, manufacturing engineers, and quality engineers who need a faster and more reliable alternative to spreadsheet-based tolerance stack-up analysis, and who work primarily with linear dimensional chains where 1D analysis is appropriate.

Particularly suited to teams performing frequent stack-up studies across multiple assemblies who benefit from CAD integration, automatic update propagation, and structured output rather than managing individual spreadsheets per analysis.

Who It's Not For

Engineers working on assemblies with complex 3D geometric relationships, angular dependencies, or mechanism kinematics where the 1D linear chain assumption introduces meaningful error. Those cases require CETOL 6σ's full 3D analysis engine. EZtol's built-in 3D effect warnings help identify when this boundary is approached, but the tool itself does not compute the full 3D result.

Platform

Windows desktop only. Compatible with CATIA, SolidWorks, and Siemens NX through direct model import. Standalone application mode available for use without the originating CAD software installed.

The same EZtol calculation technology is embedded in PTC Creo as EZTA and in Autodesk Inventor as the native tolerance analysis tool, giving engineers in those environments access to a consistent underlying methodology.

Pricing

Enterprise pricing, not publicly listed. Contact Sigmetrix directly or through a certified reseller for current pricing by configuration and user count.

Training is available through instructor-led in-person sessions, virtual courses, and self-paced computer-based programs covering tolerance analysis fundamentals through EZtol-specific workflows. A demo is available through the Sigmetrix website.

Pros

• Direct CAD model import and PMI reading eliminates manual dimension re-entry and reduces the setup errors common in spreadsheet-based stack-ups
• Automatic update propagation when shared tolerance values change keeps multiple analyses consistent without manual synchronization
• 3D effect detection alerts engineers before they rely on 1D results in situations where the geometry invalidates that assumption
• Standalone application mode makes the tool accessible to manufacturing and quality engineers without CAD software access
• Same underlying technology embedded in Creo EZTA and Autodesk Inventor means engineers already familiar with those environments share a common methodology
• Sits within the Sigmetrix portfolio, providing a clear upgrade path to CETOL 6σ when assembly complexity grows beyond 1D analysis scope

Cons

• Windows only with no cross-platform support
• 1D analysis scope means the tool cannot handle complex mechanisms, angular tolerance chains, or geometric coupling effects that require CETOL 6σ
• Enterprise pricing requires direct engagement before cost evaluation is possible
• CAD platform support limited to CATIA, SolidWorks, and NX; engineers using Creo or Inventor access equivalent functionality through EZTA and the Inventor tolerance tool rather than EZtol directly

Rating

⭐ 4.4 / 5

Editorial Take

EZtol does one thing very well: fast, practical tolerance stack-ups without unnecessary complexity. For teams performing frequent early-stage design validation, it offers a structured and reliable alternative to spreadsheet-based analysis that scales across multiple assemblies without the synchronization overhead of manual methods.

The moment an assembly problem becomes spatial, geometric, or kinematically coupled, EZtol will reach its limits. But within its intended scope, it is a well-designed tool that earns its place in a manufacturing or quality engineering workflow.

Alternatives

CETOL 6σ, 3DCS Variation Analyst, Sigmetrix EZTA (Creo), Autodesk Inventor Tolerance Analysis, Excel-based stack-up templates, VisVSA

Used In

• Mechanical assembly tolerance verification
• Automotive component and subassembly stack-up analysis
• Medical device dimensional compliance checking
• Consumer product fit and function tolerance review
• Industrial machinery assembly qualification
• Manufacturing process tolerance budgeting

Founded

1998 (Sigmetrix)