Quick calculation and what to include

To find your effective merchant processing rate (the true percentage you pay), divide the total monthly card-related fees by total card sales, then multiply by 100. Use the statement period for both figures so they match.

  1. Collect totals: total card sales (gross sales processed) and total card fees for the period. Total card fees should include interchange, assessment fees, processor markup, per-transaction fixed fees, chargeback fees, and any transaction-based adjustments.
  2. Calculate: (Total card fees ÷ Total card sales) × 100 = Effective merchant processing rate.
  3. Example: $100,000 in card sales and $2,300 in card-related fees → ($2,300 ÷ $100,000) × 100 = 2.3% effective rate.

Practical tips: Exclude non-transaction costs that aren’t tied to card volume (e.g., one-time setup or unrelated consulting). Compare effective rates across months and processors using the same methodology. If your effective rate looks high, request a fee breakdown from your provider to identify interchange inefficiencies, excessive markups, or per-transaction charges you can negotiate or optimize.