guides
How to Test Ad Truncation Before Launch
A 4-step pre-launch QA: paste copy into the simulator, switch placements, check both light and dark, screenshot the worst case.
Pre-launch ad QA is one of the highest-ROI activities a media buyer can do, and the entire workflow takes under five minutes per ad. Most ad teams skip it because Ads Manager's preview lies — it shows your ad in a desktop-width context where headlines rarely clip. Real impressions happen on phones where the visible window is significantly tighter.
The four-step pre-launch QA:
Step 1 — Paste the copy. Open the simulator, switch to your target placement, and paste your real ad copy into the relevant fields. Watch the live counter in green/yellow/red.
Step 2 — Switch placements. Cycle through every placement your campaign will run on. Watch where the copy clips on each. Stories will probably clip earlier than Feed. Reels will probably clip earliest.
Step 3 — Theme-flip. Toggle between dark and light mode preview. Some text contrasts that work in light mode disappear in dark mode (the user's setting controls which they see).
Step 4 — Screenshot the worst case. Take a screenshot of whichever placement clipped most aggressively. Send it to your creative team alongside the proposed fix. The screenshot is non-negotiable — verbal descriptions of "the copy gets clipped" lose information.
4-step QA: paste, switch, theme-flip, screenshot the worst.
Run before every launch
Spec context
| Field | Hard max | Visible before truncate | Warn at |
|---|---|---|---|
| Primary text | 500 | 125 | 110 |
| Headline | 255 | 40 | 27 |
| Description | 200 | 30 | 27 |
Source: https://www.facebook.com/business/ads-guide · Last verified 2026-04-15.
Why this routine works
It catches both character-limit failures and safe-zone failures in a single 5-minute pass. Specifically: by switching placements you see character limit drift, and by viewing the canvas you see overlay collisions. Two failure modes, one workflow.
FAQ
- Why does Ads Manager preview lie?
- Because it renders in a desktop-width context. Real impressions are on narrower phone screens. The simulator above renders the worst-case mobile crop.
- Should I do this for every ad set?
- Yes — every ad in every ad set. The marginal cost is minutes; the marginal benefit is avoiding a clipped offer.
- What if my creative team doesn't have time to fix everything?
- Triage by placement spend. Fix the placements with the most budget first. Document the rest as known issues.
- Can I integrate this into an automated workflow?
- Yes — the share-link encoding lets you save state and review programmatically. Some teams build internal QA dashboards on top.