To get more people to finish a web form, ask for less, label every field above the box, let the browser fill in what it already knows, and tell people about a mistake only after they have left the field. Each of those four changes removes a moment where a visitor stops and thinks about leaving. Most guides stop at "fewer fields". The details below are where forms actually leak.
Forms are part of UX and UI design, and they are where a good-looking site either collects an enquiry or loses it. The evidence here comes from Baymard Institute's checkout research, Nielsen Norman Group, MDN and the W3C. The research is about checkouts, and the habits it measures carry over to contact, quote and sign-up forms.
How many fields should a form have?
As few as you can reply with. Baymard's 2024 benchmark found the average checkout asks for 11.3 fields, down from 12.7 in 2019, and says most sites need only 8. A contact form with a name, an email and a message is already near the floor. Ask whether a budget range or a phone number is needed before the first reply.
The vendor blogs that rank for this topic quote neat figures such as "four fields cut completion from 25% to 20%". None of them says where the numbers come from, so don't plan around them. Plan around the question each field has to answer: what will we do with this on the first reply? If the answer is "nothing yet", move it to the second conversation.
Optional fields deserve the same suspicion. A field marked optional still costs a glance and a decision. Baymard suggests tucking optional items such as a company name behind a link instead of showing them to everyone, and putting address line 2 behind a link too. In its tests 30% of participants paused at that second address line, and some began to doubt what they had typed into the first one.
Should you split first name and last name?
No. Use one "Full name" field unless you genuinely need the parts. Baymard found that 89% of the checkouts it benchmarked have more than one name field, and that 42% of testers typed their full name into "First name" at least once. Every one of those slips is an error you then have to explain on screen.
This is a small change that rarely makes the list in form guides, because it looks like data hygiene. For a service business it is closer to courtesy. You are going to write "Hi Maria" in the reply, and a single field can be split later by whoever reads the message.
Why placeholder text is not a label
A placeholder disappears the moment someone types, so it can't do a label's job. Nielsen Norman Group lists the damage: disappearing hints strain short-term memory, people can't check their entries before sending, they can't see what a field wanted when an error appears, and a filled field is easy to overlook because eyes are drawn to empty ones.
The same article points out that light grey placeholder text usually has poor contrast and that not every screen reader reads it aloud. If your forms follow the grey look, our piece on website colour contrast and the WCAG ratios shows what ratio the text needs. The fix is a visible label above each box. A short example in the placeholder is fine once the label exists.
Does autofill really matter for completion?
Yes, and it is the cheapest win on this list. When a field carries the right autocomplete value, the browser can fill name, email, phone and address in one tap. MDN documents tokens such as given-name, family-name, email and tel. Without them the browser guesses, and a wrong guess sends people back to typing.
It is also an accessibility matter. WCAG success criterion 1.3.5, Identify Input Purpose, is a Level AA criterion: the purpose of a field that collects information about the user must be programmatically determinable, which in HTML usually means the autocomplete attribute. MDN warns against turning autofill off by default, because many users depend on it, and against inventing token values to defeat it, which fails that same criterion.
Two companion details help on phones. Use type="email" and type="tel" so the right keyboard appears, and use inputmode="numeric" for codes and similar digits. MDN notes that inputmode only changes the keyboard and enforces nothing, so it doesn't replace the right input type. Keep every box big enough to hit with a thumb; our article on tap target size on mobile websites gives the numbers.
When should a form show an error?
After the visitor leaves the field, or once the input reaches its expected length, and never while they are still typing the first character. Baymard calls flagging a field too early premature validation. It recommends clearing an error the moment the input is corrected and showing a quiet confirmation, such as a tick, when a value is valid.
Baymard's 2024 benchmark found 31% of sites give no inline validation at all, so on many sites the first sign of an error is a page that reloads after Submit. It adds that inline checks do not replace a clear message on submission, because people can still send a form with errors in it. Write that message next to the field, in plain words that say what to change.
A short audit you can run today
Open your most important form on a phone and fill it in as a stranger would. Count the fields and put a reason next to each one. Check that a label stays visible after you type. Tap the name field and see whether the browser offers your saved details. Type a wrong email on purpose and watch when and how the error appears. Then look at where the form sits in the page: a form nobody reaches doesn't need better fields, it needs a clearer path to it.
onlyspell is a digital agency that designs and builds websites and systems. If you want a second pair of eyes on a form, the consultation spell is the place to start, or talk to us about your project directly.
Frequently asked questions
How many fields is too many for a contact form?
There is no magic number. Baymard found checkout forms average 11.3 fields while 8 are enough for most sites. For a contact form, keep only the fields you need to send a useful first reply, usually name, email and message, and ask the rest in the conversation.
Are multi-step forms better than one long form?
The evidence for that is mostly vendor claims, and the figures vary between blogs. Splitting a form can help when it is long and the steps group naturally, but it adds clicks to a short one. Cut fields first, and test a split only if the form is still long.
Is it a problem to turn autocomplete off?
Usually yes. MDN says turning autocomplete off removes a feature many users depend on, including people with cognitive or motor impairments. Reserve it for fields where it is truly needed, such as one-time codes, and give personal fields the correct autocomplete value instead.
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