Sticky CTA
A sticky CTA pins the primary action (usually add-to-cart) to the viewport as the shopper scrolls. On mobile PDPs it typically lifts add-to-cart rate by 6-15%.
Sticky CTA
A primary call-to-action button that stays pinned to the viewport as the shopper scrolls — usually the add-to-cart action on a product page.
A sticky CTA is a button or bar that remains fixed to the bottom (or sometimes top) of the screen while the rest of the page scrolls underneath. On product pages the sticky element almost always wraps the add-to-cart action, sometimes paired with price and a variant summary.
The pattern matters most on mobile, where the original add-to-cart button scrolls out of view within the first two or three swipes. Without persistence, a shopper reading reviews or sizing details has to scroll back up to buy — friction that measurably depresses add-to-cart rate. Sticky CTAs are a standard component of PDP optimization and one of the highest-ROI tweaks on long product pages.
On a typical Shopify product page, the hero add-to-cart button sits above the fold. Once a shopper scrolls past the image gallery, reviews, size guide, and shipping FAQ, that button is often 4-6 viewport heights away — effectively invisible at the moment of intent.
A sticky CTA solves that gap by keeping the action one tap away regardless of scroll position. The lift is most pronounced on mobile, on long PDPs, and on considered purchases (apparel with size charts, electronics with spec tables, beauty with ingredient lists) where shoppers genuinely need to scroll before deciding.
Lift % = ((ATC_rate_sticky - ATC_rate_control) / ATC_rate_control) * 100
ATC_rate_sticky
Add-to-cart rate with sticky CTA
Add-to-cart events divided by PDP sessions, variant B
ATC_rate_control
Add-to-cart rate, control PDP
Add-to-cart events divided by PDP sessions, variant A (no sticky)
An apparel store runs a two-week A/B test on its bestseller PDP, splitting mobile traffic 50/50 between the standard page and a version with a sticky add-to-cart bar.
Control add-to-cart rate: 8.2%
Sticky add-to-cart rate: 9.4%
→ +14.6% relative lift in add-to-cart rate
A 1.2-percentage-point absolute gain is a 14.6% relative improvement — well inside the typical mobile range for this pattern and almost always worth the implementation cost.
Lift varies by PDP length, device mix, and how aggressively the original button gets buried. The shorter the product page, the smaller the benefit — there's nothing to be sticky against. The table below shows what most stores see in production.
Typical add-to-cart lift from sticky CTAs, by PDP type and device
| PDP type | Mobile lift | Desktop lift | Average page length |
|---|---|---|---|
| Apparel (size guide + reviews) | +10% to +18% | +2% to +5% | 5-7 viewports |
| Beauty / skincare (ingredients + how-to) | +8% to +14% | +1% to +4% | 4-6 viewports |
| Electronics (spec table + comparison) | +12% to +20% | +3% to +6% | 6-9 viewports |
| Food & supplements (short PDP) | +3% to +7% | ~0% | 2-3 viewports |
| Furniture / home (configurator) | +6% to +12% | +2% to +5% | 4-6 viewports |
A few implementation notes worth catching before you ship. Keep the sticky bar slim — 56-72px tall on mobile — so it doesn't eat content. Include the price and selected variant inside the bar so shoppers don't lose context. And hide it on the cart and checkout pages, where its job is done.
Sticky CTA FAQ
Yes, in almost every test on PDPs longer than three viewports. Mobile add-to-cart rate typically rises 6-15%, with the largest gains on apparel, electronics, and any product needing a scroll-heavy decision (sizing, specs, reviews). Short PDPs see smaller or negligible lift.
Trigger it after the original button scrolls out of view — usually 300-500px down. Showing it from the top duplicates the action, eats hero space, and can feel pushy. The standard pattern is invisible-on-load, fades in on scroll.
56-72px including padding is the sweet spot. Tall enough for a thumb-friendly 44px tap target, short enough not to dominate the viewport. Anything over 90px starts feeling like a second header and hurts content readability.
Bottom on mobile, full stop — that's where thumbs live. On desktop, either works, but bottom-pinned is more common and feels less intrusive than a fixed header. Some brands use a top-pinned mini-bar on desktop with the buy button right-aligned.
Not meaningfully if implemented as a CSS-positioned div rendered server-side. Watch out for third-party apps that inject the bar via JavaScript after load — they can cause layout shift (CLS) and delay LCP. Build it into the theme rather than bolting on a plugin where possible.
Price, selected variant (size, color), and the add-to-cart button at minimum. Some stores add a small product thumbnail for orientation. Avoid stuffing in wishlist, share, or compare actions — competing CTAs dilute the primary one and defeat the point.
Most modern Shopify themes (Dawn, Sense, Impulse, and similar) include a sticky add-to-cart toggle in theme settings. If yours doesn't, a no-code tool or a small Liquid + CSS snippet handles it. Test on real devices — emulators often miss iOS safe-area issues.
A sticky header pins navigation; a sticky CTA pins the buy action. They serve different intents — discovery versus conversion — and can coexist if the combined height stays under ~120px. On long PDPs the CTA matters far more than the nav.
Yes, but only because the magnitude is worth measuring. The direction is almost always positive on long PDPs; the question is whether you're getting +5% or +18%. A two-week split on a high-traffic product page is usually enough to reach significance on add-to-cart rate.
It's one of the highest-ROI tactics inside PDP optimization because it's cheap to ship, hard to get wrong, and compounds with other improvements like better imagery, clearer pricing, and stronger social proof. Most teams treat it as table stakes before tackling more complex tests.
Get an AI expert review of your site
Paste your URL — Metricuno's AI runs the same heuristic checks a senior CRO consultant would, scoring your page and prioritising the fixes that'll move conversion fastest.