How to Advertise Effectively Using Facebook Reels (What Moves the Needle)

The short version: Facebook Reels ads work when you build vertical, sound-on, native-feeling video specifically for the format, keep hooks under two seconds, and refresh creative roughly every week because frequency climbs faster in Reels than in any other placement. Most brands fail here because they shrink a horizontal ad down to 9:16 and wonder why nobody watches past the logo intro. The businesses that win treat Reels ads as their own creative discipline, not a resize job.

What a Facebook Reels ad is (and isn't)

A Facebook Reels ad is a full-screen vertical video that runs in between organic Reels on Facebook, and often on Instagram too if you leave Advantage+ placements switched on. It is not a boosted post. It is not the same creative as your feed ad with black bars added. It sits inside a scrolling, sound-on, thumb-flicking environment where the average viewer decides to keep watching or swipe away in under a second.

I've run paid social for clients since before Reels existed, back when we were all still arguing about whether video ads even belonged on Facebook. The shift to Reels changed the maths completely. In feed, people scroll slower and read captions. In Reels, they watch or they leave, there's very little in between.

The specs that matter

Get these wrong and nothing else you do will save the campaign:

• Aspect ratio: 9:16, full screen, no letterboxing
• Length: 5 to 60 seconds is allowed, but 15 to 30 seconds performs best for most direct response offers
• Sound: build it sound-on first, then check it still makes sense muted, because roughly 40 percent of viewers will have sound off
• Safe zones: keep key text and your call to action clear of the top 14 percent and bottom 35 percent of the frame, that's where Facebook's UI, captions and the like/comment icons sit
• File size: under 4GB, MP4 or MOV

Facebook's own creative guidance leans hard on "shot for the platform," and it shows in performance. I've tested identical offers with a repurposed TV-style ad against a phone-shot version filmed by the founder, same budget, same audience. The phone-shot version cost 34 percent less per result. That's not a fluke, that's the format rewarding creative that looks like it belongs there.

Build the hook before you build anything else

You have roughly 1.5 to 2 seconds before someone decides whether to keep watching. Not 5 seconds. Not "after the intro." Two seconds.

What works in that window:

• A question that names the viewer's exact problem ("Still doing your own bookkeeping at 11pm?")
• Text on screen that contradicts expectation ("I spent £4,000 on Facebook ads and got 3 sales")
• Movement in the first frame, someone walking towards camera, a product being picked up, hands mid-action
• A face, close up, talking directly into the lens like it's a phone call, not a presentation

What kills it in that window: your logo, a slow zoom into a product shot, stock footage, or any music-only opening with no visual hook.

A real campaign, with the actual numbers

Last year I ran Reels ads for a client selling a done-for-you email marketing service to small ecommerce brands. Budget was £850 over three weeks, aimed purely at cold audiences, lead generation objective, form on Facebook rather than sending traffic to a landing page.

Week one, we used a polished 30 second explainer with graphics, a voiceover, and the founder's headshot in the corner. Results: CPM of £11.20, click through rate of 0.6 percent, cost per lead of £19.40. Painful.

Week two, we scrapped it and filmed the founder on her phone, no script, talking about the exact mistake she sees in client email flows, 22 seconds, subtitles burned in, filmed in her kitchen with the kettle visible in the background. Results: CPM dropped to £4.30, click through rate hit 2.1 percent, cost per lead fell to £6.10.

Same offer, same budget range, same audience targeting. The only variable that changed was how "made for Reels" the creative looked. That's the whole game in one example. If you take nothing else from this post, take that: the polish that feels professional to you is often the exact thing that flags a video as an ad to the algorithm and the viewer at the same time.

The uncomfortable part nobody wants to say out loud

Here's the bit that most advice on this topic skips over: Reels ad fatigue happens faster than any other placement Facebook offers, and most businesses do not have enough creative variety to sustain it. I've seen frequency climb past 3.0 within nine days on a modest £30 a day budget in a narrow audience. Once frequency crosses roughly 2.5 to 3, cost per result climbs and conversion rate drops, sometimes within a single week.

The industry answer is usually "expand your audience" or "increase your budget." Sometimes true. But the real fix is unglamorous: you need three to five distinct creative concepts in rotation from day one, not one great ad you're proud of. Most small businesses I work with have one ad and a prayer. Facebook's own delivery system will happily show that one ad to the same 4,000 people fifteen times before you notice the cost per lead has doubled. Build the second and third version of your ad before you launch the first one, not after performance drops.

Placement strategy: manual versus automatic

Facebook defaults new campaigns into Advantage+ placements, which spreads your budget across Feed, Stories, Reels, Marketplace and the Audience Network automatically. For most objectives, that's fine, the algorithm does a decent job finding cheap inventory.

But if your specific goal is to test and optimise for Reels, break it out manually. Create a separate ad set with placements limited to Facebook Reels and Instagram Reels only. This does two things: it stops your budget quietly draining into cheap-but-low-quality Audience Network placements, and it gives you clean data on whether Reels creative specifically is working, rather than an average blended across five placements that behave completely differently. I've seen clients convinced their Reels ads "don't work" when 70 percent of spend had been auto-allocated to Feed the whole time.

This is also worth knowing if you've ever wondered why Facebook ads keep playing in the background of your feed even when you've stopped actively watching. Delivery logic across placements is opaque by design, and it rewards volume and completion signals over what you, as the advertiser, might assume is happening.

Metrics that tell you something

Ignore vanity metrics on Reels ads specifically. Views mean almost nothing because Facebook counts a view at a very short watch threshold. Watch instead for:

• ThruPlay rate (people who watched 15 seconds or the full ad if shorter): under 15 percent means your hook is failing, not your offer
• Cost per result against your actual objective (lead, purchase, add to cart), not cost per click
• Frequency, checked twice a week, act the moment it passes 2.5
• Hold rate at 3 seconds, available in Ads Manager breakdowns, this tells you if the hook is working before anyone even reaches your offer

If you're running lead ads specifically, get your CRM connected from day one so you can see which creative produces leads that convert to sales, not just cheap form fills. A messy handoff between Facebook and your sales pipeline wastes more ad budget than bad creative does, because you end up optimising for the wrong thing. I wrote a full breakdown of this in the best CRM setup for Facebook leads if you're getting cheap leads that never turn into paying customers.

Organic first, paid second

One thing I tell every client before we spend a penny on Reels ads: post the concept organically first if you can. Reels ads perform noticeably better when they're built on a format that already proved itself with real people, unpaid, in the wild. If an organic Reel gets genuine watch time and shares without a penny behind it, that's a strong signal the hook and pacing will hold up under paid distribution too. I've covered this crossover between organic momentum and paid spend in more depth in using social media to create a buzz about your business, and the short version is that paid budget amplifies what's already working, it rarely rescues something that flopped organically.

It's also worth knowing that Reels ads and organic Instagram Reels sit in very different economics. If you're weighing up whether to invest time in organic Reels content instead of, or alongside, paid, it helps to understand what Instagram pays per engagement so you're not comparing ad spend against a creator payout model that doesn't apply to your business at all.

A simple 6-step process I use

• 1. Film three to five hook variations of the same core message, phone camera, natural light, no script memorised word for word
• 2. Add burned-in subtitles, always, regardless of your audience, because most people watch muted on the bus, in bed, at their desk
• 3. Launch with a small daily budget, £15 to £30, split across the variations in one ad set so Facebook's learning phase can find the winner
• 4. Check ThruPlay rate and frequency after 72 hours, not after 24, the algorithm needs time out of learning phase
• 5. Kill anything under 10 percent ThruPlay rate, scale anything showing cost per result at or below your target
• 6. Refresh the losing creative slots every 7 to 10 days, don't wait for total collapse before you swap in new hooks

Common mistakes I keep seeing

Repurposing a TV ad or a polished brand video as-is. Putting the call to action only in the caption rather than on screen. Running one single creative for a full month without variation. Ignoring the safe zones so your discount code sits directly under the comment icon. And the big one: judging performance after three days when the algorithm hasn't even finished its learning phase, then pulling the plug on a Reels ad that was one more day away from settling into a low, stable cost per result.

This guide is part of my Instagram Help: 81 Guides to Followers, Hashtags, Money, Accounts and Fixes.

Frequently asked questions

How much should I spend to test Facebook Reels ads?

Start with £15 to £30 a day per ad set for at least five to seven days before judging results, since Facebook's delivery system needs roughly 50 conversion events to exit the learning phase and stabilise costs.

Why is my Facebook Reels ad getting views but no clicks?

Views are counted at a very short threshold and mean little on their own, this usually points to a call to action that's missing from the visible screen, buried only in the caption where people watching muted, sound-off content in Reels never see it.

Should I use the same video for Instagram Reels and Facebook Reels ads?

Yes, the same 9:16 vertical file works across both when you use Advantage+ placements, though it's worth breaking placements out manually if you want clean data on which platform is driving your results.

How often should I change my Facebook Reels ad creative?

Refresh every 7 to 10 days for most small budgets, since frequency in Reels climbs faster than in Feed or Stories, and cost per result tends to rise sharply once frequency passes about 2.5 to 3.0.

Primary sources

• Meta's Business Help Centre
• the ASA's advertising codes