Pipeline planFlat retainer vs percentage of ad spend: which agency fee model suits you
By Hojabr Sattari. Updated .
A flat monthly retainer stays level when your ad spend changes, which can cost less at high spend and more at low spend. A percentage of ad spend rises and falls with your budget and ties the agency fee to the size of the program. Published B2B agency prices show both: Refine Labs, Gripped, Sagefrog and Powered by Search publish flat monthly prices, while HawkSEM states 10% to 30% of ad spend and PlanConversion publishes 15%, down to 10% at higher spend, with a monthly minimum. Neither model is better in general. Compare what sits inside the fee and judge agencies on cost per qualified opportunity.
At a glance
| Criterion | Flat monthly retainer | Percentage of ad spend |
|---|---|---|
| How the fee is set | A fixed monthly amount for a defined scope | A share of the ad spend the agency manages |
| When spend doubles | The fee usually stays the same unless scope changes | The fee doubles with spend |
| When spend halves | The fee stays the same, so the agency share of budget rises | The fee halves, down to any monthly minimum |
| Predictability | High: the same invoice each month | Moderate: it follows spend, so forecast spend to forecast the fee |
| Alignment | Aligned to scope and team time | Aligned to the size of the program |
| Published examples | Refine Labs from $14,000 a month; Gripped from £3,500; Sagefrog from $4,950; Powered by Search from $6,000 | HawkSEM states 10% to 30% of ad spend; PlanConversion publishes 15%, down to 10% at higher spend, with a monthly minimum |
| Watch for | What is billed on top: creative, web work, onboarding, tools | What is inside the percentage, and whether a minimum applies |
A worked example at $50,000 of monthly ad spend
- 10% of ad spend is $5,000 a month.
- 15% of ad spend is $7,500 a month.
- 30% of ad spend is $15,000 a month.
- The scope decides the value: a higher percentage that includes creative, landing pages and reporting can cost less than a lower one with separate charges for each.
What each model rewards
A flat retainer rewards a clear scope and steady delivery, and it protects you from fee growth when you scale spend. It can leave you overpaying when you cut spend and the work shrinks. A percentage keeps the fee in proportion to the program, which suits a budget that changes by quarter, but it needs a clear view of what the agency does as spend grows.
There is also a third model: fees partly tied to agreed results, as Kalungi describes on its site. It shifts some risk to the agency but needs precise definitions of what counts. Our snapshot of published agency pricing lists each model with its source.
Questions to ask whichever model you choose
- Is ad spend inside the fee, on top of it, or billed to you directly by the platform?
- What is the minimum term and the notice period?
- Who does the work, and how much senior time is included?
- What is billed separately: creative, landing pages, onboarding, tools?
- What happens to the fee if spend doubles or halves?
- How do you report pipeline from my CRM, not only platform metrics?
Judge on outcomes
Whatever the fee model, the number that matters is cost per qualified opportunity and pipeline from your CRM. A lower fee that produces few meetings costs more per opportunity than a higher one that produces many. Run any shortlist through the same brief and the same data access.
Which one fits your team
Choose Flat monthly retainer when
- Your ad spend is large and stable, so a fixed fee will be a small share of it
- You want one predictable invoice for a defined scope
- You want to scale spend without the fee rising automatically
- You are comparing agencies with clear tiers of scope
Choose Percentage of ad spend when
- Your budget changes by quarter and you want the fee to follow it
- You are starting at modest spend and want to scale
- You want the agency fee tied to the size of the program
- You are happy with a monthly minimum that applies when the percentage comes to less
Frequently asked questions
What is a typical agency fee as a percentage of ad spend?
It varies. HawkSEM states 10% to 30% of ad spend on its site, and PlanConversion publishes 15%, down to 10% at higher spend, with a monthly minimum. Confirm what the fee includes.
Is a flat retainer cheaper than a percentage?
It depends on spend. A flat retainer can cost less at high spend and more at low spend. A percentage follows your budget. Compare the full scope, not only the headline.
Should ad spend be inside the agency fee?
Ad spend should be visible and billed to you, so you own the accounts and the data. Ask every agency how spend is billed.
Which model does PlanConversion use?
Paid media is priced at 15% of ad spend, down to 10% at higher spend, with a monthly minimum. Other programs are scoped around your budget. See our pricing page.
