POS processing fees: effective rates and break-even math

Choose the numerator and denominator together

Start with one statement period and one clearly defined set of card transactions. Use the gross processed card amount for those transactions, not total shop revenue and not the net bank deposit after deductions. Follow the processor’s transaction definitions; tax and tips may be part of the processed amount. Square’s fee documentation, for example, says its charge applies to the transaction total including tax and tip.

In the numerator, add the processing charges attributable to that same activity: percentage fees, per-transaction fees and the recurring processor fees included in your comparison. A processor’s statement can break costs into multiple components. Helcim’s statement guide shows interchange, card-network costs and its own margin separately; looking at the margin alone would not give the total.

State how you handle refunds, disputes, adjustments and one-off charges. For a repeatable comparison, show the ordinary month separately from exceptional items, then include those items in the full business-cost view. Do not quietly drop a cost because it makes an offer look less attractive.

A monthly example: 2.50% becomes 3.10%

Assume US$30,000 of eligible card sales, 1,500 transactions, a hypothetical 2.50% charge plus US$0.10 per transaction, and US$30 of monthly processor charges. There are no refunds or other adjustments in this invented example. These inputs do not represent a VoVi, Square, Toast, Shopify or Helcim offer.

Why average ticket size changes the result

The fixed transaction charge matters more on a smaller purchase. With the hypothetical 2.50% plus US$0.10 terms above, the transaction-level percentage is 2.50% + (US$0.10 ÷ average ticket × 100). The table isolates those two transaction charges; it excludes the US$30 monthly charge, software, equipment and all other costs.

Use the number of charged card transactions, not the number of customers or receipts, when your statement distinguishes them. A split payment, additional authorization or different payment channel may need different inputs. Confirm which events incur a fee before turning sales volume into an estimated transaction count.

Use a weighted card mix, not an average of rates

Different transaction categories can have different rates. In another hypothetical example, US$24,000 charged at 2.50% costs US$600, and US$6,000 charged at 3.00% costs US$180. The combined percentage charge is US$780 on US$30,000, or 2.60%, before fixed fees. Averaging 2.50% and 3.00% equally would incorrectly produce 2.75%.

Build separate rows for the categories in your actual quote, such as card-present, manually entered and online transactions, or card brands with different terms. Add category processing costs together. Count shared monthly charges only once. Preserve the same sales mix when comparing providers so the comparison does not change the business underneath the offer.

When can lower processing fees pay for software?

Suppose a hypothetical paid plan adds US$99 per month, but reduces the processing percentage by 0.30 percentage points. Assume the same card mix, fixed transaction fees, devices, other recurring fees and required features on both routes. The break-even volume is US$99 ÷ 0.003 = US$33,000 per month. A 0.30-percentage-point difference is 0.003 as a decimal, not 0.30.

At US$20,000, the reduction saves US$60 in processing and leaves the paid route US$39 more expensive after its US$99 fee. At US$50,000, it saves US$150 and leaves the paid route US$51 less expensive. These are calculated differences under the stated assumptions, not predicted merchant results.

If per-transaction fees also differ, first estimate monthly processing savings as sales volume × percentage-rate difference ÷ 100, plus transaction count × fixed-fee difference. Then subtract the additional software and recurring costs. If processing savings are zero or negative, the added subscription cannot pay for itself through processing savings alone.

For VoVi, compare the actual US processor-linked offer with US$99 per month per location plus the charges from your existing processor. The 0.30-point example is not a VoVi rate promise. The free-software route requires VoVi’s processor and merchant approval; hardware and processing remain separate. A US calculation is not an international quote.

Keep the rate useful, and keep the total honest

An effective rate is a diagnostic measure, not the entire POS price. In the first example, adding a hypothetical US$99 software subscription would make the recurring processing-plus-software cost US$1,029. Dividing that by US$30,000 gives 3.43%, but label it as a combined cost ratio, not a processing rate. Equipment, setup and other excluded costs still need their own lines.

Calculate more than one ordinary month if your ticket size or card mix changes seasonally. Keep a copy of the statements, inputs and written quote with the result. Then use the cost lab for the wider 12- or 36-month decision, including equipment and switching costs. A lower percentage is useful only when the full configuration still fits the business.