In short
Sparingly, and never on arrival. Pop-ups do convert, typically a few percent of visitors for a well-targeted offer, but full-screen modals shown immediately, on mobile, or repeatedly annoy visitors, raise abandonment, and can trigger Google's intrusive interstitial penalty. If you use one, trigger it on intent such as scroll depth, time on page or exit, show it once per visitor, make it easy to dismiss, keep it small on mobile, and offer something specific. For most content and service sites, an inline call to action at the end of the content does the same job without the interruption.
What the numbers say
Pop-up vendors publish conversion figures, and the honest summary of them is that a pop-up offering something relevant converts a few percent of the visitors who see it, with well-targeted, well-timed ones reaching high single digits and untargeted welcome mats converting around one percent. That is genuinely more email signups than an inline form usually collects, which is why pop-ups persist despite everyone claiming to hate them.
The costs are less often measured because they are diffuse: visitors who leave when the modal appears, visitors who stay but trust the site a little less, visitors on phones who could not find the close button, and the accessibility failures of a dialog that traps focus badly or does not trap it at all. Tests that measure both sides tend to find that an aggressive pop-up raises signups and lowers the page's primary conversion, and the net depends on which matters more to the business.
Google's position
Since 2017 Google has treated intrusive interstitials on mobile as a negative ranking signal: pop-ups that cover the main content immediately after a visitor arrives from search, standalone interstitials the visitor must dismiss before reaching the content, and layouts where the above-the-fold area is an interstitial and the content is pushed underneath. Exceptions are made for legal requirements such as cookie consent and age verification, for login dialogs on gated content, and for banners that use a reasonable amount of screen space.
The penalty applies to the page a searcher lands on, for the interstitial they see on arrival. A pop-up triggered later in the visit, or on desktop, or small enough not to obscure the content, is outside it. The practical reading: a full-screen welcome modal on mobile is both a ranking risk and a poor experience, and the two objections point the same way.
The formats, from worst to best
Immediate full-screen modal. Appears on load, covers everything, often with a coy decline link. Highest signup rate per impression, highest abandonment, and the format the penalty targets.
Timed or scroll-triggered modal. Appears after the visitor has read for a while or scrolled past a point, which means they have shown interest. Substantially less annoying, still an interruption.
Exit-intent modal. Appears when the cursor moves toward the browser controls on desktop. The visitor was leaving anyway, so the interruption costs little; on mobile there is no reliable equivalent.
Slide-in or corner box. A small panel that enters from the side or bottom without covering content. Visible, dismissable, much less intrusive, lower conversion per impression but far higher tolerance.
Sticky bar. A slim strip at the top or bottom. Always visible, minimal intrusion, suits announcements and simple offers.
Inline. A form or offer placed in the content, typically at the end of an article or between sections. No interruption at all; converts the readers who reached it, who are the ones worth converting. This is what most content sites should use first, and it pairs naturally with a clear call to action.
The rules if you use one
- Trigger on intent, not on arrival: scroll depth past 50%, time on page past 30–60 seconds, exit intent, or a second page view.
- Once per visitor, remembered in a cookie for at least a month. Showing the same pop-up on every page is the single most common complaint.
- Never to people who already did the thing. Subscribers should not see the subscribe pop-up.
- Easy to dismiss: a visible close button, Escape key, click outside, and no dark-pattern decline text like "No, I don't want to save money."
- Small on mobile, or a different format entirely. A modal that covers a phone screen is the penalty case.
- Accessible: focus moves into the dialog, is trapped there while open, returns to the trigger on close, and screen readers are told it is a dialog. Most pop-up plugins fail at least one of these, and our note on accessible modals covers what correct looks like.
- Specific offer. "Get the checklist we use on every audit" outperforms "Subscribe to our newsletter", because it says what the visitor gets.
- Measured on both sides. Signups gained and primary conversions or engagement lost, over a few weeks, before deciding to keep it.
When none is the right answer
Sites whose primary conversion is on the same page: a pop-up asking for an email on a pricing page competes with the button that makes money. Sites serving people under stress or in a hurry, such as support and healthcare. Sites where the brand is understated; a pop-up contradicts it. And sites without a specific, valuable thing to offer, where the pop-up asks for an email in exchange for nothing and collects addresses that will unsubscribe at the first send.
For those, the inline offer at the end of the content, a well-designed landing page for the newsletter itself, and a sticky bar for the occasional announcement collect a smaller, better list without the interruption.
The decision
If you have a specific, valuable offer, an audience that reads, and the discipline to trigger on intent, show once, and keep it small on mobile, a pop-up can add signups without much harm. If any of those is missing, put the offer inline and keep the visitor's goodwill. If you would like to test the trade-off on a specific site, book a call; it is a two-week experiment with a clear answer.
Common questions
Do pop-ups hurt SEO?
They can on mobile. Since 2017 Google has treated intrusive interstitials shown immediately to visitors arriving from search on mobile as a negative ranking signal, with exceptions for legal notices, login dialogs and small banners. Pop-ups triggered later in the visit, on desktop, or sized not to cover the content are outside the penalty.
What is a good conversion rate for a pop-up?
Around a few percent of the visitors who see it for a relevant, well-timed offer, with the best-targeted ones reaching high single digits and generic welcome modals closer to one percent. Judge a pop-up by net effect: signups gained against any drop in the page's primary conversion and engagement, measured over a few weeks.
When should a pop-up appear?
After the visitor has shown interest: past 50% scroll depth, after 30–60 seconds on the page, on exit intent on desktop, or on a second page view. Never on arrival, and once per visitor for at least a month. Visitors who have already subscribed or converted should not see it at all.
What is the least annoying type of pop-up?
An inline form or offer placed in the content, which does not interrupt anyone, followed by a small slide-in or corner box that does not cover the page, and a slim sticky bar. Full-screen modals, particularly on arrival or on mobile, are the most disliked and the format Google penalises.
Are exit-intent pop-ups effective?
On desktop, reasonably: they appear when the cursor moves toward the browser controls, so the visitor was leaving and the interruption costs little, and they convert comparably to timed modals. On mobile there is no reliable exit signal, so the equivalent is a scroll-based or time-based trigger, kept small.
