Metric, US, Imp(erial)

Needs one more measurement unit. With US/Foreign/Canadian original manufacture labeling, still some confusion (in my mind?). One more toggle would be great!

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Thanks for flagging this, it’s been on the back of my mind for a while. I want to be thoughtful about adding an extra option.

I think that, if the app supports both US and Imperial units for the pool volume, it will make the “ounces” referred to elsewhere in the app ambiguous… or, maybe they already are :sweat_smile:. See this screenshot for a contrived example (nobody would choose “metric” and then use “ounces”, but if they did, which ounces would these be? US or Imperial?):

I can see a few options:

  1. Don’t support the imperial system
    – this is a bad option

  2. Support all 3 systems for pool volume, but only US and Metric for chemical dosing
    – this also seems bad

  3. Support all 3 systems, and replace all instances of “ounces” with “US ounces” or “:us:ounces”
    – the app currently lets people cycle through “ounce” -> “pound” -> “gram” -> “kilogram”, I could change this to “US ounce” -> “US pound” -> “Imp ounce” -> “Imp pound” -> “gram” -> “kilogram”.
    – this might be the right answer, but it still seems tedious & long-winded.

  4. Support all 3 systems, but change up the settings:
    – for pool volume units, make people choose between “Liters” and “Gallons” (not US | Metric).
    – add an additional setting for US vs Imperial, which will control the meaning of gallons, ounces, and pounds throughout the app.
    – This keeps the current UX of chemical-treatment units-switching, and it doesn’t add extra words or options to the treatment dosages. However, it still might be a confusing setting, especially for metric users.

  5. Support all 3 systems, just have 1 setting for units: “US”, “Metric”, or “Imperial”.
    – If a metric user cycles through ounces or pounds on any screen, we just use US units.
    – This is probably the best balance of doing-what-users-expect vs handling-ambiguous-edge-cases.

  6. Support all 3 systems, but constrain the cycled units to whatever the user selects in Settings
    – This is similar to #5, but the app only lets the user cycle through units in the chosen system
    – I’m concerned that some people might have products that dose in grams, and other products that dose in ounces. If that’s true, then this would be really frustrating, because you would get locked-in to whatever measurement system you choose.

I’m leaning towards #5, but this edge-case is still bugging me:

  • Someone selects Imperial units
  • They have one product that doses in US ounces.

In this case, that conversion will still be manual / in their heads… but at least the app will take an explicit stance on which units to use? Also, there is only a <5% difference between a US and Imperial ounce… I’d still like to get it right, though… I dunno, I need to sleep on it :slight_smile:

What do you think?

One good thing about litres/metric, etc is they are using a base 10 model, whereas US/Imp gallons are based on 1.0gal-us = .83267 Imp-gal. I can make the metric calculations in my head, whereas anything else requires a calculator or paper/pencil at least.
But I do like option #5