Welcome to Guildline

Guildline, as of end of today, March 24, 2020 will be temporarily closing. This has been mandated by the Ontario Provincial Government for a minimum of two weeks to help contain the Covid-19 Pandemic. If governments extend this closing period we will keep you informed. Guildline will be unable to ship any products or accept any items for service during this closing period.

Please continue to contact Guildline via This email address is being protected from spambots. You need JavaScript enabled to view it. if you have any questions or require information. All emails will be answered.

All the best for you and your families during this challenging time.


Guildline Instruments is an Engineering Company that designs, manufactures and markets ultra-precise instruments for the fields of metrology and oceanography. Since 1957 our products have been used for research and as the primary instrument with respect to establishing traceability to fundamental electrical standards. Key customer markets include national research laboratories, national metrology institutes, calibration laboratories, militaries, nuclear power plants, aerospace, and companies in the electrical and power industry.

guildline logo 50years

Most Guildline instruments are unique and represent the only commercially available instrument capable of uncertainties/accuracy in the sub parts-per-million range. The team of Guildline engineering and manufacturing experts is recognized around the world for the performance and quality of the Company’s products. Most Guildline Instruments and Standards remain in use for 20 to 50 years – performance and quality that customers depend on!

Contact Guildline to assist you in overcoming all of your measurement challenges. Performance and quality for over 60 years!

What's New

  • 7330

    Guildline Instruments 7330 Series of Oil Based Resistance Standards are designed for high accuracy resistance calibration in oil (Fluid Baths) or in air.

    Download the Datasheet:

    31968-00-85_C7330.pdf TM7330-A-00.pdf