Outsourced Payroll Calculator

Decide whether to outsource payroll with a straight cost comparison. Enter your employee count, average salary, the provider’s base and per-employee fees, and your true monthly in-house cost: the calculator compares both routes monthly and annually, then gives an explicit verdict on which is cheaper.

Quick Answer

How to use the outsourced payroll calculator

Enter your headcount, the provider’s quoted fees and your honest in-house cost, then click Calculate. The results stay hidden until you click.

1. Number of employees: everyone paid through the payroll run. Fractional entries are truncated to whole people, matching how providers bill.
2. Average salary: average gross annual salary. This only feeds the total annual payroll line for context.
3. Provider base fee and per-employee fee: take both from the actual quote, monthly figures. If the quote is per payroll run instead of monthly, convert it first: multiply a biweekly per-run fee by 26 and divide by 12. Leave either field blank if the quote has no such charge; blanks count as zero.
4. True in-house cost: the monthly figure, and this is where most comparisons go wrong. Build it from the breakdown in the next section, not from your software subscription.
5. Read the verdict: green means outsourcing saves money, red means in-house is cheaper, amber means the costs are equal and you should decide on service quality.

Headcount cost is only one part of what an employee really costs a business: a cost per employee calculator puts the salary, benefits and overhead picture together, and a cost per hire calculator covers what replacing one costs you.

The formula: two monthly costs, one subtraction

The tool prices the outsourced route from the quote, takes your in-house figure as given, and subtracts. Annual saving is the monthly figure times twelve.

Notice what the formula deliberately does not do: it does not discount the annual figure, add a growth assumption, or price the provider’s tax-filing guarantee. It is a planning estimate on the numbers you enter, which keeps the arithmetic auditable. The worked example is fully reproducible: $100.00 + 25 × $10.00 = $350.00/mo, and $2,300.00 − $350.00 = $1,950.00/mo.

Worked example, checked against this exact tool

The pre-filled run is 25 employees at $50,000 average salary, provider fees of $100 base plus $10 per employee monthly, and a $2,300 true in-house cost. Every row below is a verified run of the calculator above.

The last two rows show the tool’s honest edges: at 500 employees the verdict flips to in-house (negative saving), and on an exact tie it refuses to pick a winner and tells you to decide on service quality instead.

The 5-staff bar assumes about $1,500 a month in in-house cost; the other three bars match the worked-example rows above.

Your true in-house cost is higher than you think

Most businesses compare the provider quote against their payroll software subscription and call it a day. That comparison is rigged, because the subscription is the smallest line item.

Build the in-house number from every line: staff hours spent running payroll (often 5 to 15 hours a month for a small business), the software subscription itself, tax filing and compliance work, year-end W-2 and 1099 processing, and the cost of errors. Analyses of payroll mistakes commonly cite IRS estimates that about one in three employers has been penalized for payroll errors, with small businesses paying an average of $845 a year in penalties, and industry research puts the average error correction cost far higher once staff time is counted. A realistic 25-person in-house cost often lands between $1,100 and $1,600 a month before you count management time, which is why the worked example’s $2,300 is a full-cost figure, not a pessimistic one.

Now the honest counter-case, because it changes close decisions. One widely cited analysis argues the real comparison is in-house payroll WITH modern self-service software versus fully managed outsourcing, not spreadsheets versus outsourcing. On that math, a 25-person company on self-service software plus a few HR hours per payroll run costs roughly the same as a fully managed service. When the calculator’s verdict comes out near zero, the decision is not about dollars: it is about whether that HR time is actually available, and whether you want to be the liable party when a filing goes wrong. Enter your numbers honestly and the verdict will tell you which side of that line you are on.

How providers price: PEPP vs PEPM

Outsourced payroll typically prices two ways, and you need to know which one a quote uses before you enter it.

• Per-employee-per-payroll (PEPP): a base fee of $20 to $75 plus $6 to $15 per employee per payroll run. Convert per-run figures to monthly (biweekly runs: multiply by 26, divide by 12) before entering them.
• Per-employee-per-month (PEPM): a flat $25 to $35 per employee per month, sometimes with a small or zero base fee.

Then ask about the add-ons, because they are where quotes diverge: W-2 and 1099 processing (often $4 to $10 each), off-cycle runs ($25 to $75), year-end filings, and new-state setup fees. The IRS Publication 15, the Employer’s Tax Guide, sets out the deposit schedules and failure-to-deposit penalties (2% to 15%) that make late filings expensive, which is exactly the risk a provider’s tax-filing guarantee is meant to absorb. Ask for a full itemized pricing schedule in writing, and confirm in writing whether each add-on applies to your contract.

The break-even headcount

Outsourcing usually wins below about 15 employees and the advantage narrows as you grow, because provider fees scale with headcount while in-house costs are step-fixed: one payroll person costs roughly the same whether you have 10 or 40 employees. The table above shows the shape: savings peak in the small-to-mid range and the verdict flips once headcount is large enough that an in-house specialist’s salary spreads thin per employee.

Two refinements worth making by hand after the calculator gives you its number. First, the tipping point moves with your in-house reality: if payroll is a 10%-of-one-person side task, outsourcing wins much further up the headcount scale than if you already employ a full-time payroll specialist. Second, multi-state payrolls, contractors on 1099s, and frequent off-cycle runs all push the real in-house cost above the tidy version, which favors outsourcing. If your situation includes any of those, re-run the calculator with the add-on costs included in the provider fields and a fuller in-house figure.

What competing calculators miss

The direct rivals for this keyword either compute without judging, or judge without computing:

• BraveCalculator’s outsourced payroll calculator: the closest working rival, with a similar 25-employee comparison. Gap: it shows no annual saving figure and renders no verdict, so the user does the final judgment call the tool should make.
• 1840andCo’s outsourcing cost guide: the deepest cost tables in the set, with in-house and outsourced ranges at 10, 25 and 75 employees. Gap: static ranges only, no calculator to run your own numbers through.
• BlueWaveHR’s true-cost comparison: the best breakdown of hidden in-house costs, including opportunity cost of owner time and IRS error statistics. Gap: no tool; the reader must assemble the comparison themselves.
• SaasRat’s 2026 outsourcing cost analysis: the only rival honest about the counter-case, showing self-service software plus HR time costing roughly the same as managed payroll at 25 employees. Gap: no calculator, and its conclusion is embedded in a long article rather than computable.
• HRCosts’ payroll outsourcing guide: a useful three-way split of in-house specialist, self-service software, full-service payroll and PEO bundle costs. Gap: no tool, and PEO pricing is bundled with benefits so it is not comparable to payroll-only quotes.
• TIA Payroll’s cost comparison white paper: transparent UK bureau pricing against in-house. Gap: UK-only figures and no interactive tool.
• The gap this page fills: monthly and annual saving plus total payroll context in one run, an explicit verdict wired into the output instead of left to the reader, the monthly-input disclosure stated plainly, and the self-service counter-case covered honestly rather than hidden.

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