There is no single calculator, but the arithmetic is short. Take your monthly fee, add ad spend, add creative and sourcing costs, then divide by the gross profit those products throw off. Below is the checklist that fills in each input, including the one most sellers skip: which traffic channels are actually being run.
The short version
- The formula is trivial. The inputs are not. Every bad calculator is a good formula fed by guesses.
- Use gross profit, never revenue. A percentage of revenue tells you nothing about whether the engagement pays.
- Ten inputs. Nine are numbers you already have. The tenth is a question you have to ask the agency.
- Count the channels. There are five ways traffic reaches an Amazon listing and most sellers fund two of them.
- Run it twice. Once at today's ad spend, once at double, because that is where fee structures separate.
The mistake that makes calculators useless
Most sellers build this in a spreadsheet with two cells, the agency fee and the ad budget, and divide by revenue. That version always says the agency is cheap, because revenue is the largest number on the page and the fee is one of the smallest. It also says nothing, because revenue does not pay anyone. Gross profit does.
The second version of the same mistake is calculating cost per month instead of cost per outcome. A $1,500 fee against a product with $4,000 of monthly gross profit is a different decision from the same fee against $900, even though the fee cell is identical.
The formula
Total monthly cost of being managed, divided by monthly gross profit from the managed products, gives you the share of profit the engagement consumes. Run the same arithmetic on the incremental profit you expect the work to create, and you have the case for or against hiring anyone.
The ten inputs, and what "filled in properly" means
- Management fee. The real monthly figure, not the headline tier. Ours runs $800 for one product to $2,400 for five, with the first invoice covering first and last month.
- Fee structure. Flat, percentage of ad spend, percentage of revenue, or hybrid. Write down which, because it changes every later row.
- Ad spend. Today's actual number. No hard minimum exists, though under about $1,000 a month there is not enough data for meaningful optimization.
- Amazon's per-unit fees. Referral and fulfillment, pulled from your own reports rather than estimated.
- Landed unit cost. Manufacturing plus freight plus duty, per unit, at your current order size.
- Gross profit per unit. Price minus rows four and five. This is the number the whole calculator rests on.
- Units per month. Trailing three months, not your best month.
- Creative and sourcing costs. Ours sit inside the fee because both studios are in house. If your candidate brokers them, get the line item.
- One time costs. Trademark, photography samples, tooling. Amortise across twelve months rather than dropping them into month one.
- Channels funded. The input nobody fills in, covered below.
The channel input everyone skips
Traffic reaches an Amazon listing through five routes: organic search, paid placements, promotions, influencer and creator content, and off-channel traffic driven from outside Amazon. Most sellers fund two of them, usually organic and paid, and then calculate agency value entirely inside those two.
That distorts the arithmetic in both directions. It understates what a capable agency can add, because three channels are sitting unused. It also overstates a weak agency's contribution, because running two channels competently looks like full coverage when you have never seen the other three.
So input ten is a question rather than a number. Ask each candidate which of the five they will actually run for you, who runs each one, and what the first ninety days look like on the channels you are not currently funding. Then re-run the calculator with those channels costed in. The answer usually changes the ranking.
What most agencies will not tell you about their own calculator
Any pricing calculator an agency hands you is a sales asset. It will be built from inputs that flatter the model being sold, which is why a percentage-of-spend agency's calculator starts from revenue growth and a flat-fee agency's starts from cost predictability. Mine is no exception, which is why the version above uses your numbers and asks you to divide by your own gross profit.
The other thing worth saying plainly: the fee is not where the money is. Across a year, ad spend and inventory will each dwarf what any agency in this market charges you. If the calculator you build spends most of its cells on the fee, you have built a calculator for the wrong decision.
Related answers
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- Fair Amazon agency pricing models
- Amazon agency pricing and economics: the complete guide
Plug our real numbers into your version, they are published at Flapen.
