ISO 7500-1 — Calibration & verification of static uniaxial testing machines (force measurement)

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ISO 7500-1 sets out how to verify and classify the force-measuring system of a uniaxial testing machine used in tension or compression. The verification result places the machine in an accuracy class, which then governs the tests it may be used for. To plan a verification interval or class target for your load frame, talk with our team.

What ISO 7500-1 Verifies

The standard checks how accurately a machine applies and indicates force across its working range. A calibrated force-proving instrument is loaded on the machine, and the difference between the reference force and the machine reading determines accuracy, repeatability, and resolution at each test point.

Machine Accuracy Classes

Verification assigns the force range to a class based on the permitted relative error. Lower class numbers mean tighter tolerances:

Table 1. ISO 7500-1 machine classes by permitted force error.
Class Maximum permitted relative error
Class 0.5 ±0.5%
Class 1 ±1%
Class 2 ±2%
Class 3 ±3%

Why the Class Matters

Tensile methods reference a required machine class. For example, room-temperature metal tensile testing to ISO 6892-1 expects a force system verified to a stated class, so a valid ISO 7500-1 certificate is what makes those results defensible. The verified class defines the force range over which the machine may be used for accredited work.

How Verification Is Performed

Verification uses a force-proving instrument traceable to national standards, applied at graduated points through the range in both increasing and, where required, decreasing steps. The instrument itself is calibrated to ISO 376. Results are recorded per force point and summarized as the class the machine meets.

Reading the Designation

Cited as ISO 7500-1:YYYY. Confirm the edition, since class definitions and verification details can change between revisions.

Related Standards

ISO 376 calibrates the force-proving instruments used here, ISO 9513 covers extensometer calibration, and ASTM E4 is the ASTM practice for force verification of testing machines.

Request a Quote

Need your force system verified or a machine sized to a target class? Request a quote and our team will help you build a system matched to your force range and accuracy class.


TensileMill CNC products for ISO 7500-1

Our specimen-preparation systems and testing equipment compatible with ISO 7500-1:


Equip your lab for ISO 7500-1 with TensileMill CNC

TensileMill CNC designs and builds the systems labs use for standards-based mechanical testing. Depending on your specimens, that can include load cells, alignment hardware, and the reference setups used for machine and extensometer verification. Send us your specimen types and target standards, and we will help you spec the right system.