Agency Retainer vs Project Pricing:
Which Model Fits Your Store

Choose a fixed project when the work has a clear end: a Klaviyo flow build, a CRO audit, a site migration or a BFCM push. Choose a retainer when the work compounds month to month: campaigns, ad testing and creative refresh. Expect a retainer pitch either way. In SparkToro's 2025 agency survey, 85% of agencies said they prefer retainers.

That preference reflects agency cash flow. Your needs are different, and most growing Shopify stores use both models at different times. The table below shows which fits which job.

What is the difference between a retainer and a project?

A project buys a defined output. A retainer buys ongoing capacity and attention.

With a project, the agency quotes for a scope: "build 8 core Klaviyo flows with 3 to 5 emails each, live in 6 weeks." You pay for the result. If the agency underestimates, it absorbs the cost. If you add to the scope, you pay a change order.

With a retainer, you pay a flat monthly fee for a team doing recurring work. For example: 8 campaigns a month, weekly ad creative testing and a monthly report. The agency plans around steady capacity. You get continuity and faster response.

The risk sits in different places. Projects risk scope fights. Retainers risk drift, where the fee stays the same and the output slowly shrinks.

Neither is cheaper by default. A good retainer delivers more per dollar than a string of projects because there is no re-scoping each month. A bad one costs more because nobody checks what shipped.

When is a fixed project the right choice?

Pick a project when you can describe the finish line in one sentence. Common examples for Shopify brands:

• Klaviyo flow build. Welcome, abandoned cart, browse abandonment, post-purchase, win-back. Our Klaviyo flows revenue benchmarks show what each should return.
• Audit. A one-time review of your store, ads or email with a prioritized fix list.
• Site or theme migration. A fixed set of templates and a launch date.
• BFCM campaign. A planning, build and send window with a clear end. The BFCM playbook shows the timeline.
• Tracking setup. Pixel, Conversions API and event checks.

Projects also work as a first date. A small audit tells you how an agency thinks, communicates and handles your data before you commit to monthly fees.

Projects fail when the work needs iteration. A flow build without anyone to test subject lines or update offers loses value within a few months.

When does a retainer make more sense?

Pick a retainer when the value comes from repetition and learning. Three signs:

1. The work restarts every month. Email campaigns, ad creative, landing page tests. Each cycle uses what the last one taught.
2. Speed matters. A stock-out, a viral product or a price change needs action this week. A retainer team already knows your account.
3. You need judgment, not just hands. Budget shifts, offer decisions and channel mix need someone who sees the full picture monthly.

Retainers suit stores with enough revenue for the fee to pay back. Paid media is the clearest case. Meta needs a steady stream of new creative and budget decisions, which our Meta ads agency pricing post covers.

Retainers fail when nobody defines the output. A retainer with no list of monthly deliverables becomes a subscription to "being available." Write deliverables down, even if they change quarter to quarter.

What do retainers and projects cost?

Sources disagree, so here are both sides.

SparkToro surveys agencies of all sizes worldwide, and its retainer data includes small shops. Clutch draws on pricing data from 106,043 listed companies and the projects reviewed on its site. If you are hiring a US agency, use Clutch's US hourly band as your reference point.

Use the hourly rate as a sanity check. At Clutch's US band, a 40 hour audit works out to $4,000 to $5,960. If a quote is far above that, ask what the extra hours cover.

Channel-specific ranges are in our posts on Klaviyo agency pricing and Shopify CRO agency cost. For the in-house comparison, see the cost of a senior Klaviyo or Meta hire.

How does a hybrid model work?

Three hybrid structures work well for ecommerce.

Build, then run. A fixed project builds the foundation, such as Klaviyo flows and segments. A smaller retainer then runs campaigns and testing on top. You pay for the heavy lift once.

Base plus project add-ons. A retainer covers recurring work. Bigger one-off pieces, like a BFCM build or a new landing page, are quoted separately. This keeps the retainer honest about what is "included."

Base plus performance bonus. A flat fee covers the work, plus a capped bonus tied to an agreed metric. Pick a metric that the agency can influence and that you can verify in Shopify, such as email revenue share or new customer CAC. Avoid platform-reported ROAS as the trigger, because attribution windows can flatter it.

Whatever the structure, give each piece its own scope and its own exit. A project should not lock you into the retainer that follows it.

How should you structure a trial month?

A paid trial month is the lowest-risk way to test an agency on live work. Make it a short, fixed project with clear deliverables, not a discounted first month of a 12 month contract.

A good trial month covers:

• Access and audit. The agency gets access through your own accounts and documents what it finds.
• Baseline. Revenue, email share of revenue, new customer CAC and conversion rate on day one, recorded in writing.
• 2 or 3 shipped items. For email, a rebuilt welcome flow plus two campaigns. For paid, a creative test with a written result.
• A 90 day plan. What they would do next, in order, with expected effort.
• A conversion decision. On day 30, you choose: convert to a retainer, run a project, or stop.

Do not judge revenue impact from a single month. Judge the quality of thinking, the speed and how they communicate. Plan the revenue read for later, with reviews at 60 and 90 days, which is why the contract terms for the follow-on retainer matter.

Which model fits your revenue stage?

Revenue changes the answer. These bands match our guide on when to hire an ecommerce agency.

Under about $20k a month. Skip both. Agency fees take too large a share of revenue. Set up core flows yourself using Klaviyo's templates, keep ad spend modest and fix product pages. A one-time audit is the most you need.

$20k to $150k a month. Start with a project. A flow build or a CRO audit fixes the biggest gaps fast. Add a light retainer for campaigns or ad management once the project pays back. A freelancer can be the right call for a single channel here.

Over $150k a month. A retainer usually makes sense for at least one channel, often email plus paid. The work is constant and speed matters. Keep large one-off pieces as separate projects.

Not sure how much revenue is at stake? The revenue gap calculator gives a quick estimate before you talk to anyone.

What should a retainer include so it does not drift?

Write four things into every retainer.

1. Monthly deliverables. Count them: campaigns sent, flows updated, ad concepts launched, tests run.
2. Response times. How fast the team answers a question and how fast it ships an urgent change.
3. Reporting cadence. What arrives weekly and what arrives monthly, and which metrics lead.
4. Review points. A quarterly reset where scope can go up, down or end.

Also agree what happens to unused capacity. Some agencies roll it over for one month. Others do not. Either is fine if it is written down.

Then check it. Once a month, compare what shipped with the list. A retainer that hits its list most months is healthy. One that misses for two months in a row needs a conversation, not a renewal.

How do you move between models?

Switch from project to retainer when you find yourself buying a new project every month. That is a retainer with extra paperwork.

Switch from retainer to project when the account is stable and the work has become maintenance. A store with mature flows and steady campaigns can often run on a quarterly project instead of monthly fees.

Either move is normal. A good agency suggests it before you ask. The bigger decision of agency vs freelancer vs in-house is covered in our guide to hiring an ecommerce marketing agency and our Klaviyo agency guide.

If you want to talk through which model fits your store, you can book a call at /contact. We work with 100+ D2C brands and quote each store individually.