Thanks for this. Agree it depends on the context. And we like boring too ^_^ In our case, it's an optional / configurable preference, so I think we check that

Thanks for this. Agree it depends on the context. And we like boring too ^_^ In our case, it's an optional / configurable preference, so I think we check that box. Put another way, this isn't a blanket policy applied to all numeric input fields. Instead it's just for one particular input field, where large numbers are entered. Now we don't want the users to have to enter the thousands separator manually (and besides, the raw integer is ultimately what is stored too). So what we've currently got is the input field, with the formatted preview adjacent to it, kinda like so: [123456789 ] Formatted preview: 123,456,789 And as the input box is keyup'd, the formatted preview is refreshed. I personally think this strikes the right balance, but I was curious what other good solutions the folks here on HN have seen to this problem. Thanks for your comment ^_^