Hot answers tagged measurements
Go to Settings → Document Settings on the top right of the page and change the language to English (UK). Rulers and margins will now both be in centimetres (cm). You may need to log out and sign back in before you see the changes take effect.
This is not possible in the current version of Google Docs with "English (US)" regional settings. Until they change this you can convert millimeters to inches using this Google query: <n>mm in inches Or you could follow the tips in Dominiks answer, and change your language settings to "English (UK)".
Due to recent changes, the measuring system in Google Docs is now affected by your Google Account default language, not any more by the document language as indicated in @Dominik's answer. So: Go to myaccount.google.com/language. You can also reach it via the gear icon on the Google Drive or Google Docs main pages. Set the language to "English – United ...
If you have an iPhone, you could try the Ego app. It covers Google Analytics and Mint and a few other.
There is a feature request for metric units here https://forums.loseit.com/posts/list/60/178.page which is active since 2009. So according to the forum thread, as of writing this answer,metric units are not available for Lose it! yet.
Most of the analytics tools has an API you can use to login and pull data. Just a matter of doing it for each tool and making an interface for yourself. But on a side-note... trying to track things with multiple tools dooms you to a life of headache, as you will always be wondering and asking why numbers never exactly matchup.
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