Your form converts fine on desktop and dies on mobile — and since mobile is where most of your traffic lives, the blended number looks like a lead problem when it’s actually a thumb problem. Mobile form friction is invisible in analytics and obvious the moment you fill out your own form on your own phone, slowly, like a stranger would.
On desktop, a clumsy form is an annoyance. On a phone, it’s a reason to leave — and your visitors are on phones.
The keyboard nobody set up
Tap a phone-number field and get the full alphabet keyboard: now the visitor is hunting for the number toggle before typing a single digit. HTML has solved this for years — type="tel" for phones, type="email" for emails, inputmode="numeric" for anything numeric — and half the forms on the web still don’t use it. The right keyboard appearing instantly is the difference between typing and fiddling, and Google’s form best-practices documentation treats it as table stakes.
Autofill fighting the visitor
Phones can complete name, email, phone, and address in one tap — if the form lets them. Fields missing proper autocomplete attributes, or split into fragments browsers can’t map (three boxes for a phone number is the classic), force manual typing of information the phone already knows. Every field autofill completes is friction deleted for free.
Targets built for cursors, not thumbs
Checkboxes rendered at 16 pixels, form fields shorter than a fingertip, links crowding the submit button — precise on a desktop, a mis-tap festival on a phone. Inputs need comfortable height (44px minimum touch targets), full-width layout, and breathing room around the one button that matters. And that button must never hide behind the keyboard: the visitor finishes the last field, sees no way to submit, scrolls confusedly, sometimes leaves.
Validation that punishes
The cruelest mobile pattern: submit, fail validation on one field, and watch the form reload with every other field wiped. Retyping everything on glass is where submissions go to die. Errors should appear inline, next to the field, as it’s completed — never after a round-trip, never at the cost of entered data. The second-cruelest pattern is the vague error: “Invalid input” on a phone field that secretly wanted no spaces. Say what’s wrong and what right looks like.
The friction you can simply delete
Every optional field earns its place or gets cut — on mobile the field-count tax roughly doubles. CAPTCHAs are conversion killers on phones; modern invisible protection (honeypots, time-based checks, reCAPTCHA v3) blocks the same bots without making a human squint at hydrants. And multi-step forms with one question per screen often outperform long single screens on mobile, because each step feels effortless.
The two-minute test that finds all of this
Phone in hand, fill your own form as a first-time visitor: wrong keyboards, ignored autofill, tiny targets, buried buttons, punishing errors — you’ll feel every one. These are small builds individually, which is exactly why they’re standard in every small business site I ship: the form is the site’s whole job, and mobile is where the job happens.