Are there any recommended guidelines for how much a data a mobile-friendly website should consume during casual browsing?

For desktop browsing, data consumption is not so much of an issue, so long as load times are good. However, many mobile users may be on a fixed data plan, and will avoid visiting websites known to gobble up their data.

(Example scenario edited out, as it seems to have distracted from the actual question.)

  • This is something you can talk to your web developer about as there are solutions to the issue. One specific term to use with them is "lazy loading". But this is not a UI/UX issue. – Rob Dec 1 at 13:15
  • @Rob I was familiar with the concept of "preloading" (images), but not with "lazy loading", which is new to me. Thank you, I believe that will solve my immediate problem. – Gooseberry Dec 2 at 5:13
  • @Rob The issue is UX with respect to the experience of a user visiting a site and discovering it has gobbled up a huge amount of their data plan. Such a site has a "poor UX" as compared with other sites. – Gooseberry Dec 2 at 5:16
  • Apart from my immediate problem (provided for example purposes) I would still be interested to know the answer to the actual question: How much data consumption is "too much", if there are any such guidelines from standards bodies or large organizations, such as Google, Microsoft, Apple, or Mozilla. – Gooseberry Dec 2 at 5:18
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    @locationunknown I did not research extensively: 1) Google search on "website design reasonable mobile data rates", 2) Stack Exchange UX search on "website design mobile data rates". These did not turn up very good results. However, they did turn up a similar SE question <ux.stackexchange.com/questions/29659> that unfortunately focused more on load times, but inspired me to ask my question instead. I had much better results today with a Google search on "website design mobile data rate consumption guidelines". – Gooseberry Dec 3 at 2:53

In 2018, a mobile webpage should be no larger than 500 KB. This recommendation is based on a widely cited marketing report (web|pdf) from Google "Find Out How You Stack Up to New Industry Benchmarks for Mobile Page Speed" (2017, Daniel An), which marks 500 KB as a "best practice".

It is unclear from the article exactly how this number was derived, but I believe the line of reasoning is as follows:

  1. Goal: Minimize website bounce rate.
  2. Model risk of bounce as a function of webpage load time, itself a function of webpage size.
  3. Pick a best-practice webpage size that most greatly minimizes the risk of bounce.

Specifically, the article reports the following benchmark results:

  • 1s to 3s the probability of bounce increases 32%
  • 1s to 5s the probability of bounce increases 90%
  • 1s to 6s the probability of bounce increases 106%
  • 1s to 10s the probability of bounce increases 123%

I believe the article is inferring that the greatest gains lie in the range under three seconds, which in turn is the load time used to derive the page-size recommendation of 500 KB.

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