Weve been following the Toolwatch guys since their early start and they did a great job in creating a tool to measure the accuracy of your watch. First via their website, but now theres also the Toolwatch app available in the Apple Store and Play Store (Google).Checking the accuracy of your watchFor most of you watch enthusiasts out there, accuracy is an important aspect of your mechanical watch. The chronometer (COSC) standards is one way to guarantee the accuracy of a watch (down to -4/+6 seconds a day on average), but it is only valid for 5 years and perhaps -4 seconds a day still isnt good enough for you. Also, the chronometer testing and certification only applies to the movement itself. After this certification, the movements are being sent back to the manufacturer to be cased. Brands like and Omega take it a few steps further, by doing additional tests (and certification) on the complete watch. This way, guarantees the accuracy to be within -2/+2 seconds a day and Omega within 0 5 seconds day.Other brands, like Jaeger-LeCoultre and Grand Seiko for example, have their own test procedures and accuracy standards. However, these arent proofed or certified by third parties.So how can you measure the accuracy of your watch? Well, with the toolwatch app, you measure the time at one moment (the initial measuring time) and after 12 hours, you measure it again with the help of the app. The Toolwatch app (and website) then checks it with the atomic time servers. Et voila, they present you the difference between the actual time and the time indication on your watch, measures over 12 hours and synced with the atomic clock.