National Physical Laboratory

Gauge Block Calibration Services

Calibration of gauge blocks by interferometry.

Gauge blocks
Gauge blocks

NPL services for interferometric (Class A) calibration of gauge blocks

Gauge blocks are among the most commonly used standards for maintaining traceability in engineering. Before use, all gauge blocks must themselves be calibrated according to various specification standards such as BS 4311, BS EN ISO 3650, and ISO 3650. Gauge blocks must also be re-calibrated periodically to maintain their accuracy. In order to satisfy these requirements NPL offers a comprehensive UKAS-accredited calibration service for gauge blocks from 0.5 mm to 1000 mm in length. This service is available by prior booking.

Calibration service details

NPL's gauge block calibration service offers the following features:

  • interferometric calibration of central length
  • verification of measurement face flatness
  • verification of variation in length
  • interferometric calibration of coefficient of thermal expansion (lengths over 100 mm)
  • calibration to ISO 3650, BS 4311, BS EN ISO 3650
  • calibration of steel, tungsten carbide or ceramic gauge blocks

Download flyer outlining Gauge Block measurement services available (Adobe Acrobat PDF file PDF 128 KB)

Gauge block types we can calibrate for you

NPL can measure the following grades of gauge block:

  • Grades K, 0 of (BS EN) ISO 3650
  • Grades K, 0 of BS 4311 (2007)
  • Grades Calibration, Reference, 00, 0 of BS4311 (1968) and BS 888
  • Grade 1 of (BS EN) ISO 3650 (by mechanical comparison)

Information on the types of gauge blocks we can measure (Adobe Acrobat PDF file PDF 281 KB) is also available.

Measurement uncertainty

Gauge block central length measurement uncertainty: ±[0.019, 0.00021L] µm at 95 % confidence level (where L is the length of the gauge in mm).

NPL's gauge block services are covered by the CIPM MRA and are UKAS-accredited.

Further information



Customer Service tel: 020 8943 8631

Last Updated: 18 Aug 2015
Created: 21 Oct 2011


Please note that the information will not be divulged to third parties, or used without your permission