Committee title

Consultative Committee for Length (CCL)

CGPM-2026 CCL report

28th meeting of the CGPM

Report of the CCL to the CGPM

Read the report of the Consultative Committee for Length (CCL) to the 28th meeting of the General Conference on Weights and Measures (CGPM).

Read the CCL report →

President

Chief Metrologist

National Measurement Institute, Australia

Australia

Executive Secretary

Bureau international des poids et mesures

France

List of meetings

Meetings and related documents

CCL-WG-N

23
October
2026

CCL-WG-N

CCL-WG-CM

23
October
2026

CCL-WG-CM

CCL-TG-DIG

20
October
2026

CCL-TG-DIG

CCL-WG-S

20
October
2026

Asset Publisher

CCL-TG-DIG

CCL Task Group on Digitalization

CCL-WG-CM

CCL Working Group on Coordinate Metrology

CCL-WG-MRA

CCL Working Group on the CIPM MRA

CCL-WG-N

CCL Working Group on Dimensional Nanometrology

CCL-WG-S

CCL Working Group on Strategic Planning

CCL-CCTF-WGFS CCL-CCTF Frequency Standards Working Group

CCL DGs

Discussion Groups

CCL-DG1 CCL Discussion Group on Gauge Blocks

CCL-DG2 CCL Discussion Group on Thermal Expansion

CCL-DG3 CCL Discussion Group on Angle

CCL-DG4 CCL Discussion Group on Cylindrical Diameter Standards

CCL-DG5 CCL Discussion Group on Step Gauges

CCL-DG7 CCL Discussion Group on Linescales

CCL-DG8 CCL Discussion Group on Surface texture

Publications

Publications

Meeting reports

[CCL] 19th meeting (2024)

[CCL] 18th meeting (2021)

[CCL] 17th meeting (2018)

Guidance documents on the CIPM MRA

[CCL] CCL-GD-1
Running of MRA comparisons in length metrology and monitoring their impact on CMCs

ccl-mission

Mission

The Consultative Committee for the Definition of the Metre (CCDM) was set up in 1952. Its name was changed to Consultative Committee for Length by the CIPM in 1997.

Present activities concern matters related to the definition and realization of the metre, practical length and angle measurement, and advice to the CIPM in the field of length metrology.

Nested Applications

Asset Publisher

News and Updates

BIPM150 Interview: Prof. Ken Alder on the Revolutionary Origins of the Metre

Follow along as Professor Ken Alder speaks to the BIPM about the radical ideas behind the original metric system—and its subsequent evolution.

The origins of the metre explained on French radio

The show Sciences Chrono was dedicated to a pioneering geodetic survey in the 1790s that was the basis of the original definition of the metre.

WMD 2024 Launch Event hosted at UNESCO headquarters

First celebration of World Metrology Day following the formal proclamation by UNESCO.

Reports and announcements

Report of Session II of the 115th meeting of the CIPM (2026)

Annual Review Supplement - Activities of the BIPM Departments 2025

BIPM Annual Review 2025

Report of Session I of the 115th meeting of the CIPM (2026)

Report of the 114th meeting of the CIPM (2025)

CIPM Strategy 2030+