Future Media Standards & Guidelines

Download Standards v2.0

1. Introduction

This standard gives the basic requirements and recommendations for creating pages with acceptable load times. The perceived quality of the user experience of browsing bbc.co.uk can be directly affected by the download time of its pages (how long it takes for a page to finish loading on a user's browser). The simplest metric for measuring this is the page weight limit - meaning the total weight (in KB) of an HTML page and its inline objects.

On consideration, we have identified a new method using proprietary tools that are already familiar to many web developers and designers.

For the purposes of this standard Page weight should be regarded as: 'The total amount of downloaded data from the initial page request until the loaded page is completed and stable with no ongoing downloads (not including any further data loaded as a result of user action / event e.g. mouseover, onclick, etc).'

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2. Optimising your pages

2.1 You MUST optimise the weight of your pages – pages MUST be as small as possible, whilst still supporting the editorial proposition of the page.A1

2.2 Please see the following guides below for more details on optimising your pages:

There are also tools available to help you, see the wiki page on the bbcimg service [Internal BBC document Internal BBC doc].

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3. Size restrictions and measurement

3.1 All pages on bbc.co.uk SHOULD have a maximum page weight of 500KB.

3.2 You MUST use Yahoo’s YSlow and Google’s PageSpeed with Firebug for Mozilla’s Firefox to test your page’s download performance.

3.3 Pages of 500KB or less MUST have an average performance score (average of scores from YSlow and PageSpeed) of 60 or more.

3.4 Pages of 500KB to 750KB or less MUST have an average performance score (average of scores from YSlow and PageSpeed) of 70 or more.

3.5 Pages of 750KB to 1MB MUST have an average performance score (average of scores from YSlow and PageSpeed) of 80 or more.

3.6 Your pages MUST NOT be larger than 1MB.

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Appendix A: Why

  • A1. If you can make changes to the implementation of a page which decrease its weight (or download size) without adversely affecting the content, function and presentation of the page, the resulting page is considered to be of better quality and one that delivers an improved user experience.

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