ISO 376 is an international standard for calibrating and classifying force-proving instruments (such as force transducers/load cells with an indicator) that are used to verify the force performance of uniaxial materials testing machines in tension and/or compression.
If you need help matching ISO 376 expectations to your verification approach (and to the ISO 7500-1 machine verification workflows it often supports), contact our team to talk through your setup and documentation needs.
ISO 376: Metallic materials — Calibration of force-proving instruments used for the verification of uniaxial testing machines
ISO 376 focuses on the calibration of force-proving instruments that act as reference devices when checking the indicated force of a uniaxial testing machine. It is commonly used in lab and production environments where force traceability and documented verification of a test frame are required.
It is typically applied in static force verification contexts. While ISO 376 supports force metrology for materials testing, it is not a materials test method for a specific product; it is a calibration and classification standard for the reference force device used in verification.
Quick definition
ISO 376 in one line: A standard method to calibrate and assign an accuracy class to force-proving instruments used to verify the force-measuring performance of uniaxial (tension/compression) testing machines.
What this standard covers
ISO 376 specifies a calibration procedure for force-proving instruments and a way to classify them based on their measured performance during calibration.
It applies to force-proving instruments where the applied force is determined from elastic deformation of a loaded element (or a quantity proportional to that deformation), which is a common principle for many force transducers and proving devices used as transfer standards.
Why this standard matters in testing
When a tensile/compression testing machine is used for standards-based mechanical tests, confidence in reported results depends on the accuracy of the machine’s force measurement. ISO 376 supports that confidence by defining how the reference force device itself is calibrated and classified before it is used for machine verification.
In practical terms, ISO 376 is often part of a traceability chain: a calibrated and classified force-proving instrument is used to check (and document) whether a test frame’s indicated force meets a required performance class during verification.
Common materials, product types, or applications covered
ISO 376 is not limited to a single metallic product form; it is used wherever uniaxial testing machines are relied on for force-accurate testing. Common application areas include:
- Metals testing labs running tensile and compression tests that require documented force accuracy
- Manufacturing QA/QC programs that verify test machines on a defined schedule
- Accredited calibration and test laboratories supporting force traceability programs
- Machine service and verification teams responsible for force performance checks
Common test or verification workflow
ISO 376 commonly supports a verification workflow that looks like this at a high level:
- Calibrate the force-proving instrument using a suitable calibration system and procedure.
- Classify the instrument based on the measured performance characteristics defined by the standard.
- Use the calibrated force-proving instrument as a reference when verifying the force indication of a uniaxial testing machine across its working range.
- Document results in a calibration/verification record appropriate to your quality system and any referenced machine-verification standard.
Practical note: Because the force-proving instrument becomes the reference for machine checks, its capacity range, accuracy class, and mechanical interfaces (threading, adapters, alignment features) should be selected to match the test machines and force ranges you need to verify.
Equipment commonly used for this standard
ISO 376 influences equipment selection more through metrology capability than through a single test fixture. Common equipment categories include:
Force-proving instruments: Force transducers (load cells) with an indicator, and other elastic-deformation-based force reference devices used as transfer standards.
Calibration/verification setups: Force calibration systems or reference machines capable of applying known forces in a controlled, repeatable way over the required range.
Mechanical integration hardware: Compression platens, tension adapters, spherical seats, couplers, and alignment accessories used to reduce parasitic loading and improve repeatability when mounting the force-proving instrument.
Data capture and reporting: Instrument indicators, software, and reporting tools appropriate for storing calibration points and generating calibration records.
If you are selecting a reference load cell/indicator package or planning a verification kit across multiple machines and force ranges, you can request a detailed quote for a configuration matched to your lab’s capacities and mounting interfaces.
How to read this designation or revision
Standard number: ISO 376.
Year suffix: The year (for example, “ISO 376:2011”) identifies the edition being cited. Requirements and acceptance criteria for calibration/classification can vary by edition, so purchasing decisions and compliance documentation should reference the exact year required by your customer, regulator, accreditation scope, or internal procedure.
Current edition context: ISO 376:2011 is an established edition and has been periodically reviewed within ISO’s maintenance cycle, so it is important to keep your internal procedures aligned with the edition you cite.
Related standards, methods, or frameworks
ISO 376 is commonly used alongside standards that specify how to verify or calibrate a testing machine’s force-measuring system. A frequent companion is ISO 7500-1 (tension/compression testing machines), which describes calibration and verification of the machine’s force measurement and typically relies on calibrated force reference devices.
Some organizations also reference other national or sector standards for force verification (for example, ASTM practices in North America). When multiple frameworks apply, the key is ensuring the reference device calibration/classification and the machine verification method are compatible with the exact compliance requirement you must meet.
Talk with us about ISO 376-aligned verification equipment
If you are building an ISO 376-oriented force verification workflow—selecting reference load cells/indicators, adapters, or a calibration approach—talk with our team about capacities, interfaces, and documentation expectations for your application.
