Joined: Jan 2009
Posts: 44,222
Likes: 6,476
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
I suspect a good way to check a gauge's accuracy is to compare it with two other gauges and then interpolate.
The only gauge I use is the one built into my cheap floor pump. It may be inaccurate, but it's good enough to give me pressures that feel right and don't cause pinch flats.