What do your marketplace operations cost? Agency, in-house or owned

How do you use the calculator?

Pick a model under "Show the inputs for" and fill it from your own paperwork: the agency's proposal, your payroll or job offers, and any written quote for a system. The result always shows all three models side by side, so you can switch groups without losing what you typed. The only built-in dollar amounts and percentages are public pay data from the U.S. Bureau of Labor Statistics (BLS). Every agency fee, build price, hosting bill and license starts blank, because a default there would read like a market price, and there is no single market price.

The in-house column starts with one person in each of three roles, so it shows a number as soon as the page loads. That is a shape to edit, not a recommendation. The agency and owned-system columns each start with one operations person kept on your payroll, because in every model someone still owns inventory and approves the decisions that matter. Change any count to match your plan, including 0.5 for a part-time role.

Every model is costed the same way. One-time costs land in year 1, running costs repeat every year, and sales stay flat for all three years, with no raises, inflation or discounting. The table shows exactly what goes into each column, so you can check any result by hand with the formula panel under the calculator and a spreadsheet.

Three-year cost = year 1 + year 2 + year 3, with sales held flat and no raises or inflation

Three years is long enough for one-time costs such as a setup fee, recruiting or a build to show their real weight, and short enough to be about the team and systems you would actually run. The result also names the lowest three-year cost among the models you filled in and, if you enter them, shows each model as a share of your sales and of your contribution margin.

What goes into agency costs?

Start with the fee clause of the proposal. Agencies price in a few recognizable ways, and each one goes into a different field. The examples below are from agencies' and vendors' own pricing pages, all checked September 25, 2026. They show how fees are structured, not what your agency should charge, and none of them is built into the calculator.

A fee tied to growth, such as Marknology's share of revenue above a baseline, comes to zero here, because the calculator does not project growth. To test a month with growth, add that month's fee to the retainer. The ad spend itself is not in the agency column at all: you pay it in every model, so it cancels out. What does belong there is everything the fee leaves out, such as subscriptions you still pay for and the people you keep on payroll to manage the agency and run inventory. Our guide to what an Amazon agency costs covers published fee ranges in more depth.

Reseller accelerators and aggregators are not in this calculator, because money moves the other way: a reseller buys your stock at wholesale and earns the spread to retail, and an aggregator buys the brand outright. Our comparison of accelerators, aggregators and agencies explains those models. With an agency, the accounts should stay yours, so check before you sign that your company, not the agency, owns each seller and ad account and holds its top-level access. Our checklist for switching agencies without losing your data lists what to confirm.

What goes into an in-house team?

Salaries, benefits, recruiting and the tools the team needs. BLS has no occupation called "Amazon manager", so the calculator maps each role to its closest BLS occupation and uses the national median wage for May 2025: software developers, logisticians, and market research analysts and marketing specialists (all checked September 25, 2026).

The benefits step is easy to get wrong in two opposite directions. The BLS Employer Costs for Employee Compensation release for June 2026 puts private-industry wages at $32.82 per hour worked, 70.0 percent of compensation costs, and benefits at $14.07, the remaining 30.0 percent (checked September 25, 2026). Because 30 percent is a share of the total, not a markup, the step for pay per hour worked is to divide by 0.70, which adds about 43 percent rather than 30.

A salary is different. BLS counts pay for time off as a benefit: paid leave was 7.5 percent of private-industry compensation in June 2026, mostly vacation (3.8 percent) and holidays (2.2 percent), according to Table 1 of the release (checked September 25, 2026). A salary already pays for those days, so dividing it by 0.70 counts paid leave twice. The calculator divides salaries by 0.775 instead, using the other 22.5 percent of benefits, which adds about 29 percent. Dividing by 0.70 would overstate the three-person team by $41,068 a year; a flat 30 percent markup happens to land close, at $386,178.

The rest of that 22.5 percent already covers what an employer must pay by law. The BLS technical note for the release counts five kinds of benefit: paid leave, supplemental pay such as overtime and nonproduction bonuses, insurance, retirement and savings, and legally required benefits, which are Social Security, Medicare, federal and state unemployment insurance and workers' compensation (checked September 25, 2026). So do not add the employer's Social Security and Medicare contributions again. The average holds for these roles too: in Table 4, management, professional and related occupations come to 22.2 percent (31.5 minus 9.3 for paid leave).

Medians are national, so replace them with the offers you would actually make. Senior hires and some cities cost more: BLS puts the top 10 percent of software developers above $214,670 a year in May 2025. Add the software, tools and hosting the team will use; our SaaS stack comparison lists public prices for common seller tools. For the wider trade-offs of hiring, including the months before a new team has working systems, see Ecomsellertool vs an in-house team.

Recruiting is a year-1 cost for each person hired. SHRM's 2025 benchmarking release, from a survey of its members in early 2025, puts the average cost per hire at $5,475 for nonexecutive roles and $35,879 for executives (checked September 25, 2026). Those are averages across all kinds of jobs, so the field starts blank: enter your recruiter's fee or your own past cost per hire. The calculator charges it once per person; if you expect to replace someone within three years, raise the figure to cover a second search.

What goes into an owned system?

An owned system is software that runs your operations on your own seller and ad accounts, built once and then maintained. Its cost has five parts: the one-time build, yearly maintenance and support, hosting, any licenses, and the people who still run it. Take all five from a written quote. Our page on Amazon SP-API development cost shows the ranges we see in our own work; treat them as our experience, not a price list, and none of them is built into this calculator.

Ask about hosting even when a quote leaves it out. For Zonkeepers, an accounting firm, we built a pipeline on AWS that ingests Amazon order and finance reports: raw data in Amazon S3, structured data in Amazon RDS or Aurora, and processing in AWS Lambda. Those are the kinds of lines that end up in the hosting field: storage, a database that grows with your order history, and compute billed by use. Ask the vendor for an estimate at your order volume and whose cloud account it runs in.

The maintenance percentage is charged in all three years, including the build year, so this column errs on the high side. If part of the system is licensed rather than built for you, turn the license terms in your quote into a monthly figure for the licenses field; a one-time license fee can go into the build cost instead. The team that remains matters as much as the software: someone approves purchase orders, shipments and ad changes. If you are still deciding whether to build at all, our guide to build vs buy for Amazon seller software covers that decision.

Ecomsellertool builds the owned-system option. We deploy Growth OS on your own seller and ad accounts, then build the custom modules and AI agents your operation needs, each scoped in an architecture doc with a fixed price and go-live date. You keep your accounts, your data and the custom code we build; the Growth OS base is licensed to you. Ask us for a quote and enter it here.

How do you compare the three fairly?

The easiest mistake is to set an agency's retainer against a full in-house payroll, or a build quote against nothing at all. Before you trust any total, check that each column covers the same work over the same period, with the same people counted on your side of the table.

Then look past the totals. The fair comparison is contribution margin after fees, ads, fulfillment and people, not top-line growth. Enter your monthly contribution margin after ads under "Pay, benefits and margin", and the calculator shows each model as a share of it. If you expect one model to bring more sales than another, test it as a break-even rather than a forecast. Your contribution margin ratio is your monthly contribution margin after ads divided by your monthly sales:

Extra monthly sales needed = (higher three-year cost − lower three-year cost) ÷ 36 ÷ contribution margin ratio

For example, a $180,000 gap over three years at a 25 percent contribution margin after ads needs $180,000 ÷ 36 ÷ 0.25 = $20,000 a month in extra sales just to break even. Those numbers are only for the arithmetic, not a benchmark. If your break-even looks unlikely, the lower-cost model wins on your numbers.

When is each model the right choice?

An agency is the better choice when you need advertising and marketplace expertise now, your volume would not keep specialists busy full time, and you want short notice terms rather than a build. Marknology's published terms, for example, are a "90-day minimum, then month-to-month with 30 days notice either direction" (checked September 25, 2026). An in-house team fits when marketplace operations or software are central to what you sell and a technical leader has years of roadmap to keep people busy. An owned system fits repeatable operations work across channels over three years or more. You can also mix them: an agency for creative work alongside an owned system for inventory and orders.

Want real numbers for your own account?

A calculator is only as good as the quotes you put in it. If you want a fixed quote for the owned-system column, schedule a call from the card below. If you would rather start with your data, the free 24-hour diagnostic looks across your Amazon account: you connect with Login with Amazon, no password is shared, and we only read data; we never change listings, prices, stock or ads. Within 24 hours of connecting, on business days, you get a report of what is going wrong in your operations, with a dollar estimate where the data supports it. For other decisions, try the other free calculators.