Why this question is harder than it looks
Every comparison page on this topic is written by one of the three options, so it lands on that option. I've been the in-house growth lead at brands like Varsity Tutors and Wuffes, I've managed agencies from the client side, and now I'm the fractional person. So I'll try to be fair and tell you where I'm biased.
The honest answer is that the right choice depends on two things: how much of the problem is judgment and how much is hands. Agencies sell hands. Fractional leaders mostly sell judgment. In-house people can be either, depending on who you hire. Most brands at $5M to $80M need both and can afford one and a half, which is why this is hard.
The comparison
| Agency | In-house hire | Strategy-only fractional CMO | Embedded fractional growth lead | |
|---|---|---|---|---|
| What you're paying for | A team's hours on your channels | A person's full attention | Senior judgment and direction | Senior judgment plus hands in the work |
| Typical cost | 10% to 20% of ad spend, often with a minimum | $150k to $300k+ fully loaded, plus a hiring gap of 3 to 5 months | $8k to $22k a month | $7.5k to $20k a month |
| Who owns the blended number (MER) | Usually nobody. The agency reports its channel's ROAS | The hire, if they're senior enough | The fractional CMO, on paper | The growth lead, with their name on it |
| Incentive | Keep the account, grow the spend | Stay employed | Stay retained | Build something you own, then move seats or step back |
| What's left when they go | Ad accounts and a reporting deck | Whatever they documented | A strategy document | Systems, SOPs and a trained team |
| Best when | You have a clear strategy and just need volume | You have steady work for a full-time person and time to hire | You have a strong execution team that lacks direction | You need direction and hands at once, on a budget |
What each one is structurally unable to do
An agency can't be objective about your spend, because its fee is a percentage of it. That's not a character flaw; it's the pricing model. It also almost never owns the blended number, so you'll get a strong channel ROAS and a weak business.
A full-time hire can't be hired quickly and can't be un-hired quickly. If you guess wrong on seniority you either pay a leader to do a manager's job or ask a manager to do a leader's job. And a single in-house person rarely has the creative production, tooling and measurement skills all at once.
A strategy-only fractional CMO can't fix what they can't touch. If the plan says "test six new creative angles a month" and nobody on your team can produce them, the plan is a wish.
An embedded fractional growth lead, which is what I am, can't scale to be your whole department. I'm one person. When the work outgrows me, the right move is to hire under the system I've built, and I'll say so.
When I'd tell you to pick each one
Pick an agency when you already have a strong internal owner of strategy and measurement and what you need is production volume on one channel. Manage them against MER and contribution margin, not their own ROAS.
Pick an in-house hire when you have six-plus months of steady, well-defined work for that person and the system they'll run already exists. Hiring someone into chaos rarely ends well for either of you.
Pick a fractional growth lead when the strategy isn't settled, the measurement is a mess, the creative isn't getting tested, and you can't justify a full-time senior salary yet. That's the situation I get called into most, and the goal is to leave you in the second situation above.
Questions people ask
Can a fractional growth lead work with our existing agency?
Yes, and it's often the best first move. I set the targets, own the MER and contribution-margin scorecard, and manage the agency against it. Sometimes the result is a better agency relationship. Sometimes it's bringing the work in-house, which I'll help you do.
Will hiring a fractional lead mean firing our agency?
Not automatically. Decide that after a quarter of measuring them on the blended number instead of their own reporting. Some agencies look great under that light.
Is a fractional growth lead cheaper than an agency?
Above roughly $50,000 to $75,000 a month in ad spend, usually yes, because agency fees scale with spend and a flat retainer doesn't. Below that the fees are similar, and the question is what you get for the money.
We already have an in-house marketer. Do we need this?
If they own strategy and measurement and have time to build, probably not. If they're a strong operator who has been asked to also be the strategist, a fractional lead sitting beside them for a few months tends to make them much better, and then I get out of the way.
Why do agencies say a fractional leader can't execute?
Because most of them can't, and because the agency's business depends on the execution staying with the agency. It's true of strategy-only fractional CMOs. It isn't true of the seat I sit in.