I think it depends on the layout of the form to be honest.

For example, a site I used to work on, the "Join Us" form was quite large, gathering various data. But it was laid out in separate sections which were easily discernible, with plenty of information about which sections meant what, and which fields were mandatory and it didn't stop signups.

So in summary, if you lay out your form nicely into relevant sections and inform the user of what each bit means, then you shouldn't have too many problems.

These are my thoughts, Many other people's milages may vary ;-)

Cheers,
Nige

Thanks Nige.

You need to think about the little internal debate your user has as he progresses through your system. He sees the first short form, he thinks "ah, a form, hmmmm, not too long" and fills it in.

Your next page will then present him with a form requesting some further information and he thinks "not another one! not to worry, i've filled in one and this is shortish".

If you then send him yet another form, you are really in the realm of him weighing "I've spent five minutes already on this sign up and don't want to waste that" against "I've spent long enough already and am going elsewhere".

Expectations can be managed through stage numbers (Stage 1 of 4); and I advise this where a long form cannot be avoided. Showing the user the whole form, all at once, is not recommended as it will simply scare off many potential members.

20 fields or more is not bad, when most of them are optional. The main overlooked problem with developers making forms, is that they forget that not all visitors need to enter the same information and that a lot of fields which may look different actual contain equivalent information. Only those fields that are necessary for a proper automated processing of the form should be mandatory.

Some examples:

I have stopped counting the number of US based websites that pretend to target an international audience but at the same time require foreign visitors to select one of the 50 US states when entering an address. I have no problems with the field itself, but with the developers that make it mandatory.

The "better" US site developers automatically change the state selection box with a mandatory province box for foreigners. Hey US developers, that your postal system and tax processing logic can't work well if the state isn't known doesn't mean that you should copy that behaviour to other countries.

In the Netherlands the postal code and house number make a unique combination and there are databases available which translate postal code and house number combinations to a complete address including street number and place. This may not be available in other countries, but if it is, try to use it to reduce the number of fields someone has to fill.

If someone needs to enter contact information to contact him in case there is a need for, but where there is no crucial need to know this information to proceed with the form processing, the developer should make the form in such a way that one of the following items should be enough:

• email address
• telephone number
• mobile number
• fax number
• postal address

Community services which require subscriptions like forums should initially allow people to enter only a few necessary fields like username and password. Once the user becomes an active part of the community, he will automatically extend his profile and personal settings.