ISO 9513 is an International Standard for the static calibration of extensometer systems used in uniaxial testing. It is commonly used to qualify strain-measurement performance for tensile and other uniaxial test setups where extensometer accuracy class and traceable calibration records matter.
This standard is especially relevant when you are using axial or diametral extensometers (contacting or non-contacting) for modulus, yield/offset determinations, strain-controlled testing, or any workflow where strain is a controlled or reported result. If you need help selecting an extensometer class or planning a calibration approach that fits your test program, talk with our team.
ISO 9513:2012 — Metallic materials — Calibration of extensometer systems used in uniaxial testing
ISO 9513:2012 defines a structured approach for calibrating extensometer systems used in uniaxial testing by comparing the extensometer’s indicated displacement to a known (traceable) displacement from a calibration apparatus. The intent is to support consistent, comparable strain measurement performance across labs and over time.
Because extensometers can be a major contributor to uncertainty in stress-strain results, ISO 9513 is often used as the reference for extensometer accuracy classification and calibration reporting when strain results are contractual, regulatory, or quality-critical.
Quick Definition
ISO 9513 is a calibration standard for extensometer systems used in uniaxial testing, specifying a static calibration method for axial and diametral systems, including both contacting and non-contacting extensometers.
What This Standard Covers
ISO 9513 focuses on static calibration of extensometer systems used to measure displacement (extension) over a defined gauge length in uniaxial testing. It addresses the comparison of “true” displacement from a calibration device versus the extensometer output across one or more defined measuring ranges.
Extensometer systems in scope: Axial and diametral extensometer systems, including contacting clip-on / contacting systems and non-contacting systems.
Core outcome: Documented calibration results that support classification and acceptance of extensometer performance for test reporting and quality systems.
Why This Standard Matters in Testing
When strain is measured poorly, tensile curves can shift, modulus values can be biased, yield/offset calculations can drift, and strain-controlled tests can become unstable. ISO 9513 helps reduce these risks by defining a consistent calibration framework for the extensometer system used to generate strain measurements.
This is also a practical requirement for many labs because customers, accreditation programs, and internal QA systems commonly expect traceable calibration evidence for displacement/strain measurement devices used to generate reported results.
Common Materials, Product Types, or Applications Covered
ISO 9513 is written for metallic materials testing, but the calibration concepts are broadly relevant anywhere an extensometer is used for uniaxial test measurement and reporting.
Common use cases: Tensile testing programs that report stress-strain curves, modulus, yield/offset, elongation over a defined gauge length, or that use strain feedback for test control.
Common extensometer types: Clip-on axial extensometers, diametral extensometers for round specimens, and non-contacting extensometry systems (for example, optical/video-based systems) where the measurement system can be calibrated and documented.
Common Test or Verification Workflow
ISO 9513 supports a calibration and verification workflow around the extensometer system rather than a specimen test method. In practice, it is often used as part of a broader quality system for tensile and other uniaxial tests.
Common workflow: Define the extensometer measuring range(s) to be used in testing, set up the extensometer in a representative configuration, apply known displacements using a calibration apparatus, record extensometer indicated values, evaluate performance against acceptance criteria/class requirements, and generate a calibration record suitable for audits and customer review.
Practical caution: Results can be sensitive to how the extensometer is mounted and aligned, the gauge length definition used for the test program, and whether the calibration range matches the strains actually used for reporting or closed-loop strain control.
Equipment Commonly Used for This Standard
ISO 9513 typically points to metrology-oriented equipment for applying and measuring known displacement, plus fixtures/adapters that let the extensometer be mounted the way it is used in real testing.
Common equipment: Extensometer calibration apparatus (extensometer calibrator), traceable displacement reference hardware, mounting fixtures/adapters for axial and diametral extensometers, and data acquisition/software to capture calibration points and generate reports.
System selection tip: If your lab uses multiple gauge lengths, multiple extensometer models, or both contacting and non-contacting extensometry, a calibrator with flexible fixturing and sufficient displacement range can simplify compliance across your full test scope.
How to Read This Designation or Revision
ISO 9513:2012 refers to the ISO 9513 standard published in 2012. In procurement documents, test procedures, and customer specifications, it is good practice to cite the full designation (including the year) so the calibration method and reporting expectations are unambiguous.
ISO standards can also be updated by technical corrigenda. If a customer contract or audit requirement specifies a corrigendum in addition to the base standard, your calibration documentation should match the exact cited designation.
Related Standards, Methods, or Frameworks
ISO 9513 is commonly used alongside uniaxial test methods that rely on extensometer-based strain measurement and that specify an extensometer accuracy class or calibration expectation. It may also be compared with similar extensometer calibration practices used in other standards systems (for example, ASTM extensometer calibration standards) when multi-standard compliance is required.
Get help configuring extensometer calibration equipment
If you are equipping a lab for ISO 9513 work—especially across multiple extensometer types or ranges—we can help you match a calibrator, fixtures, and reporting approach to your extensometry and uniaxial testing workflow. For equipment configuration and pricing, you can request a detailed quote.
