Retargeting budget caps at scale

Quick Answer

Retargeting budget should be capped at a fixed percentage of prospecting spend — not optimised for ROAS. Without a cap, retargeting will keep absorbing budget because attributed ROAS looks great, but most of those conversions would have happened anyway. The right caps: 10-20% for ecommerce, 15-25% for high-consideration purchases, 20-30% for B2B with long sales cycles.

The Framework

1. Why caps beat ROAS-based budgets

ROAS makes retargeting look infinitely scalable because attribution is generous. Caps force discipline — you can only spend so much on retargeting regardless of what attribution says, which means the budget goes to genuinely incremental cold acquisition instead.

2. Set the cap based on cold spend, not absolute number

If cold prospecting is at $5k/day and your cap is 20%, retargeting maxes at $1k/day. If prospecting drops to $4k/day, retargeting should drop to $800. The ratio matters more than the absolute number.

3. Different funnels, different caps

Ecommerce direct response: 10-20% retargeting. SaaS trial: 15-25%. B2B demo request: 20-30%. Ecommerce subscription: 15-20%. The longer the consideration cycle, the more retargeting matters.

4. Cap by audience age, not just budget

Beyond a cap on total budget, cap individual retargeting audiences by recency: 7-day cart abandoners get the most spend, 30-day visitors get less, 90-day visitors get almost nothing. Age-decay your retargeting effort.

5. Run quarterly hold-out tests to validate the cap

Every quarter, pause retargeting in one geo for 2-4 weeks. If revenue doesn't drop proportionally, your cap is too high. Tighten it. If revenue drops noticeably, your cap is right or could even be loosened slightly.

6. Resist the temptation to 'just spend a bit more on retargeting'

Every account we've worked with has wanted to overspend on retargeting because the attribution looks irresistible. Hold the line. The freed budget always produces more value in cold prospecting.

Real Numbers from the Field

A homeware brand we audited had no retargeting cap and was running 38% of total budget on retargeting at $4.2k/day. Reported retargeting ROAS was 7.4. We capped retargeting at 18% ($2k/day) and a hold-out test showed 65% of the 'lost' retargeting conversions still happened — meaning real incremental retargeting was much smaller than reported. The freed $2.2k/day went to cold and produced 28% more new customers in the following month.

Frequently Asked Questions

What if I'm getting amazing ROAS on retargeting?

You're probably getting credit for conversions that would have happened anyway. Run a hold-out test. The numbers will surprise you.

Should the cap include brand search retargeting?

Branded search is usually outside Facebook entirely (Google), but if you run brand campaigns on Facebook, treat them as retargeting and include them in the cap.

How do I structure retargeting if my product has long consideration?

Higher cap (25-30%), longer windows (60-90 days), and more focus on educational content rather than discount offers. Long consideration buyers respond to information, not urgency.

Should I retarget across multiple platforms or just Facebook?

Diversifying platforms helps if your audience uses multiple. Facebook + Google + maybe TikTok. Don't over-focus on Facebook retargeting alone.

What about win-back campaigns for past customers?

Run them as a separate campaign with their own budget and incremental measurement — not lumped into retargeting.

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