Two readers visit the same article. One glances at the first paragraph and leaves in eight seconds. The other reads to the end over six minutes. With a basic ad setup, both visits earn roughly the same, because the ads load once when the page opens.
That is a missed opportunity. The second reader spent six minutes with your content and your ads on screen, and advertisers value that attention. Viewability is how the market measures it, and responsible ad refresh is how publishers turn engaged time into extra revenue.
What ad viewability means
An impression is counted when an ad is actually rendered on the page - an ad that was sent but never shown is not counted. A viewable impression is one that a person actually had a chance to see. The widely used industry standard:
| Ad type | Pixels in view | Continuous time |
|---|---|---|
| Display | At least 50% | At least 1 second |
| Large display (over 242,500 pixels) | At least 30% | At least 1 second |
| Video | At least 50% | At least 2 seconds |
Viewability rate is simply viewable impressions divided by measured impressions. If 1,000 ads were served and 640 met the standard, your viewability is 64%.
Why buyers pay more for viewable inventory
Advertisers increasingly buy on viewable impressions, or use viewability to decide how much to bid. A slot that is seen 80% of the time is simply worth more to them than one seen 30% of the time. Higher viewability therefore tends to raise your eCPM, and more viewable impressions per visit raise your RPM.
What drags viewability down
- Ads below the fold that load immediately. They are served when the page opens, but most readers never scroll that far.
- Footer and deep-sidebar placements that sit outside where people look.
- Slow pages. If the ad arrives after the reader has already scrolled past, it is never seen.
- Short visits. Readers who bounce quickly generate impressions that do not reach the one-second mark.
Six ways to raise viewability
- Lazy-load ads. Request an ad only when its slot is about to scroll into view. Fewer impressions are wasted and the ones you serve are far more likely to be seen.
- Favour in-content placements. Ads between paragraphs are passed by readers as they read. See where to place ads.
- Use sticky units wisely. A bottom anchor on mobile and a sticky sidebar on desktop stay in view for the whole visit, which gives them very high viewability.
- Reserve space for every slot so the page does not jump when an ad appears. Stable layouts keep readers on the page.
- Speed up the page. Faster pages mean ads render before the reader moves on. Our page speed guide covers the basics.
- Remove dead slots. A unit that is almost never seen drags your average down and adds weight to the page. Move it or remove it.
What ad refresh is
Ad refresh replaces the ad in a slot with a new one after a set time, while the reader is still on the page. Each refresh is a new ad request and, if filled, a new impression. For a reader who stays several minutes, one slot can serve several ads instead of one.
Responsible refresh rules
Refresh done badly annoys readers and misleads advertisers. Done well, it is widely accepted. Follow these rules:
- Only refresh visible ads. An ad that is scrolled out of view or in a background tab should never refresh.
- Use a sensible interval. 30 seconds of viewable time is a common minimum. Shorter intervals look like manipulation.
- Cap the number of refreshes per slot per page view.
- Pause when the tab is hidden and resume only when the reader comes back.
- Respect each demand partner's policy. Some buyers do not want refreshed inventory, or require it to be declared. Follow the rules of every partner you work with.
A simple example
An in-content slot on a long guide receives 10,000 page views a month. Readers who reach it stay on average 2.5 minutes with the slot on screen.
- Without refresh: 10,000 impressions.
- With a 30-second refresh on visible slots, capped at 5: many readers generate 3–5 impressions from the same slot. Even if the average rises only to 2.4 impressions per view, that slot now serves 24,000 impressions.
Refreshed impressions may bid a little lower than the first one, so eCPM can dip slightly, but total revenue from the slot rises substantially. Judge refresh by RPM, not eCPM.
Which formats suit refresh
- Good candidates: in-content display and native units on long articles, where readers spend real time with the slot on screen.
- Poor candidates: interstitials, which should appear rarely, and video players, which follow their own rules.
Measuring the effect
- Compare RPM for pages with refresh against the same pages in the weeks before.
- Watch viewability: responsible refresh on visible slots should keep it high.
- Keep an eye on time on page in your analytics to confirm readers are not put off.
How Advorex Media handles viewability and refresh
The Advorex Media tag requests each display ad shortly before its slot scrolls into view (about one screen ahead) and reserves each slot's space in advance. It measures viewability on every ad - a viewable impression is at least half of the ad on screen for a continuous second - and uses it to decide when a slot may refresh. Refresh applies to display and native units: a slot refreshes only while at least half of it is on screen and the tab is active, waits at least 30 seconds between ads and stops after a fixed number of refreshes per page view.
Key takeaways
- A viewable display impression is at least 50% on screen for at least one continuous second.
- Higher viewability attracts higher bids; lazy loading, in-content and sticky placements and faster pages raise it.
- Responsible refresh (visible slots only, 30 seconds or more, capped, paused in hidden tabs) turns engaged reading time into extra revenue.
- Judge viewability and refresh changes by RPM over full weeks.
Frequently asked questions
What counts as a viewable impression?
The common industry standard is that at least 50% of the ad's pixels are on screen for at least one continuous second for display ads, and at least two continuous seconds for video ads.
What is a good viewability rate?
Many publishers aim for 60–70% or higher across their units. More useful than any target is comparing your own units: a unit far below the others is usually placed where readers rarely look.
Is ad refresh allowed?
Refreshing ads is common and accepted when it follows the rules of your demand partners: refresh only visible ads, after a reasonable interval, and never so often that it misleads buyers. Always check each partner's policy.
Will refresh lower my eCPM?
Refreshed impressions can bid slightly lower than the first impression on a page, so average eCPM may dip a little, but total revenue and RPM usually rise because engaged readers generate more viewable impressions.
Turn these tips into revenue
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