Flat-rate cost breakdown
2.90% + $0.30/transaction + $0.00/month + $0.00 additional monthly.
- Percentage fee: $1,450.00
- Transaction fees: $300.00
- Monthly fixed fee: $0.00
- Additional monthly fees: $0.00
Total modeled monthly fees: $1,750.00.
Merchant Processing Fee Calculator
Currency changes formatting only; no FX conversion. Enter applicable pricing for your country and provider.
Additional monthly fees
One generic additional monthly fee for each plan, such as statement, service or platform fees. No fee database or automatic network charges.
Interchange-Plus costs less
Estimated savings per month
$580.00$6,960.00 annualized savings estimate.
| Measure | Flat Rate | Interchange- |
|---|---|---|
| Monthly processing | $1,750.00 | $1,170.00 |
| Effective rate | 3.50% | 2.34% |
| Annualized cost | $21,000.00 | $14,040.00 |
| Monthly difference | — | $580.00 |
| Annualized difference | — | $6,960.00 |
Signed differences are Flat Rate minus Interchange-Plus. Positive favors Interchange-Plus; negative favors Flat Rate.
Processed volume: $50,000.00. Transactions: 1,000. Average transaction: $50.00.
Educational fee estimate based only on entered pricing and volumes. Unentered assessments, network charges, AVS, batch, PCI, chargeback, cross-border and other fees are not modeled. Actual pricing and terms vary by country and provider. Lower modeled cost is not a processor recommendation or guaranteed savings. Annualized estimates assume the same monthly inputs for 12 months.
Why this plan costs less
- Percentage-based fees are $400.00 lower for Interchange-Plus at these inputs.
- Per-transaction fees are $200.00 lower for Interchange-Plus at these inputs.
- Fixed monthly fees are $20.00 lower for Flat Rate at these inputs.
- Together these contributions make Interchange-Plus the lower modeled cost at this volume and transaction count.
Interchange-plus cost breakdown
1.80% average interchange assumption + 0.30% processor percentage markup + $0.10/transaction + $20.00/month + $0.00 additional monthly.
- Estimated interchange: $900.00
- Processor percentage markup: $150.00
- Transaction markup: $100.00
- Monthly fixed fee: $20.00
- Additional monthly fees: $0.00
Total modeled monthly fees: $1,170.00.
Break-even monthly volume
Break-even assumes your current average transaction size stays the same as monthly volume changes.
$1,666.67Approximate transactions at break-even: 33.33.
Flat RateBelow crossing← Break-even →Interchange-PlusAbove crossing
Text equivalent: Below the crossing Flat Rate costs less; above it Interchange-Plus costs less, under the constant-average-ticket assumption.
At average ticket $50.00, Flat variable-cost slope = 3.5000%; Interchange-Plus slope = 2.3000%. Fixed fee difference (Interchange-Plus − Flat) = $20.00. Variable rate difference = 1.2000 percentage points.
Solution: fixed fee difference ÷ variable rate difference (decimal). Per-transaction costs enter each slope as fee ÷ average ticket. Full precision is used; approximate transactions may be fractional.
A lower average ticket makes per-transaction fees a larger share of processing cost. Effective rate summarizes total modeled fees divided by processed volume; it does not identify every underlying charge.
Average interchange is a user-entered assumed or observed average, not a universal rate. Actual interchange can vary by card type, brand, rewards tier, transaction type, acceptance method, merchant category, card mix and other network/payment characteristics.
Educational fee estimate based only on entered pricing and volumes. Unentered assessments, network charges, AVS, batch, PCI, chargeback, cross-border and other fees are not modeled. Actual pricing and terms vary by country and provider. Lower modeled cost is not a processor recommendation or guaranteed savings. Annualized estimates assume the same monthly inputs for 12 months.
How to use
Compare flat-rate vs. interchange-plus fees in seconds.
Compare Plans starts with monthly card volume, transaction count and two editable fee structures. Review the lower modeled cost, effective rates, component breakdown and break-even assumption. Statement Check converts entered statement totals into an effective rate, optionally comparing them with both entered plans. Volume What-If keeps baseline average ticket fixed while a slider or numeric amount changes modeled volume. Additional monthly fees provides one optional generic field per plan. Copy Fee Comparison includes current results, assumptions and breakdowns. Print Comparison preserves the calculation and disclaimer. Reset restores the default plans, 50,000 volume and 1,000 transactions, and clears what-if/statement values, errors and copy state.
How flat-rate processing fees work
Flat monthly cost = monthly card volume × percentage rate + transaction count × per-transaction fee + monthly fixed fee + enabled additional monthly fees. A quoted flat percentage and per-transaction charge are separate components. This model applies the entered values to the whole volume; it does not infer a provider contract or additional charges.
How interchange-plus pricing works
Interchange-plus monthly cost = volume × average interchange rate + volume × processor percentage markup + transaction count × processor per-transaction markup + monthly fixed fee + enabled additional monthly fees. Average interchange and processor markup stay separate in inputs and breakdowns. The interchange percentage is an assumed or observed user-entered average, not a universal 1.80% rate. Actual interchange varies with card type, card brand, rewards tier, transaction type, acceptance method, merchant category, card mix and other network/payment characteristics. The percentage-only assumption is not a card-level fee schedule.
Average transaction size
Average transaction size = monthly processed volume / monthly transactions. At the default 50,000 volume and 1,000 transactions, average ticket is 50. Use volume and counts from the same period and compatible transaction definitions. Compare Plans requires positive volume and a whole transaction count of at least one; it never invents average ticket from zero transactions.
Effective processing rate
Effective processing rate = total modeled processing cost / monthly processed volume × 100. This combines percentage, per-transaction and entered monthly charges into a summary ratio. For an entered statement, use entered total fees / processed volume × 100. Effective rate does not identify every underlying processor charge, hidden fee or billing error. No universal good or bad effective-rate benchmark is applied.
For a separate pricing question, check the difference between markup and margin using your unit cost and selling price. Product gross margin and payment-processing effective rate use different cost definitions; keep processing fees separate when interpreting the pricing result.
For advertising economics, check advertising break-even with processing costs included once. Convert fees to the appropriate per-order basis and reconcile them with the chosen cost model rather than deducting them twice.
How to compare processing plans
Compare identical business volume and transaction count under the two entered plans. Signed difference = Flat Rate cost − Interchange-Plus cost. Positive means Interchange-Plus has lower modeled cost; negative means Flat Rate does. Costs differing by no more than 0.05 currency units are approximately equal, so no winner is forced for a few cents. Deterministic explanations show the percentage, transaction and fixed-fee contribution differences. Annualized cost = monthly cost × 12; annualized savings estimate = monthly savings × 12, assuming the same inputs every month. Lower modeled cost is not a processor ranking or switching recommendation.
Break-even processing volume
Break-even assumes your current average transaction size stays the same as monthly volume changes.
Let V be monthly volume and T the current average ticket. Transactions at V = V / T. Flat variable slope = flat percentage rate + flat per-transaction fee / T. Interchange-Plus variable slope = average interchange rate + processor percentage markup rate + processor per-transaction markup / T. With percentage rates expressed as decimals, break-even volume = (Interchange-Plus fixed monthly fees − Flat fixed monthly fees) / (Flat variable slope − Interchange-Plus variable slope). Fixed totals include enabled additional monthly fees.
Equal slopes and equal fixed costs mean plans are identical under this model. Equal slopes with different fixed costs mean the lower fixed-cost plan stays cheaper. A zero or negative solution has no positive crossing; the engine states which plan is lower for positive volumes. A positive crossing beyond supported magnitude is unavailable rather than replaced with a fake threshold. When a usable positive solution exists, below/above directions come from the slope signs. Approximate transactions at break-even = break-even volume / current average ticket, using unrounded values.
Why transaction size matters
Per-transaction fees take a larger share of volume when average ticket is smaller. A per-transaction fee divided by average ticket gives its variable-cost share at a constant ticket size. Therefore increasing transaction count while holding volume unchanged can change the modeled cost difference and break-even result. A plan with a lower percentage may still have higher total modeled fees because of transaction and fixed charges.
Statement effective-rate check
Statement Check converts entered total processing fees into an overall effective processing rate: fees / processed volume × 100. Transaction count is optional for the effective-rate-only calculation. To compare the current statement with the two entered plans, enable the optional comparison and enter a valid whole transaction count; per-transaction fees then use the statement count. The tool does not parse statements or detect billing errors. Blank statement fields are cleared by Reset; Load statement example fills the reviewed example.
To compare effective rates across matching periods, use consistently defined statement fees and processed volume. Distinguish a percentage-point change in effective rate from its relative percentage change.
What happens as sales volume grows
Volume What-If keeps the baseline average ticket fixed. Estimated transactions = new monthly volume / baseline average ticket, without rounding before calculating fees. The slider covers 10,000–250,000 currency units, with a numeric field accepting positive custom values up to the supported maximum. If a custom value is outside the slider range, the thumb is capped and an explicit note confirms calculations use the numeric amount. The result recalculates transactions, both costs, effective rates and monthly/annualized differences. Fractional transaction estimates express the constant-ticket model rather than actual observed counts.
Worked examples
1. Flat-rate monthly cost
Volume $50,000.00, 1,000 transactions. Flat percentage contribution $1,450.00; transaction fees $300.00; fixed fee $0.00; additional fees $0.00. Total $1,750.00; effective rate = total / volume × 100 = 3.50%.
2. Interchange-plus components
Volume $50,000.00, 1,000 transactions. Estimated interchange $900.00; processor percentage markup $150.00; transaction markup $100.00; fixed fee $20.00; additional fees $0.00. Total $1,170.00; effective rate 2.34%.
3. Modeled savings
Flat $1,750.00 − Interchange-Plus $1,170.00 = $580.00 monthly estimated savings. Annualized savings = monthly savings × 12 = $6,960.00, assuming constant monthly inputs.
4. Statement effective-rate check
Entered statement fees $2,391.00 / processed volume $72,450.00 × 100 = 3.300207% (display 3.30%). This is an effective-rate summary, not a hidden-fee finding.
5. Break-even at the current average ticket
Average ticket $50.00. Flat slope 3.5000%; Interchange-Plus slope 2.3000%. Fixed fee difference $20.00; variable slope difference 0.012000 in decimal form. Break-even monthly volume: $1,666.67; approximate transactions: 33.33. Below the crossing Flat Rate costs less; above it Interchange-Plus costs less, under the constant-average-ticket assumption.
Break-even assumes your current average transaction size stays the same as monthly volume changes.
Assumptions and limitations
Monthly and statement processed volume must be positive, up to 1 trillion. Observed transactions must be whole numbers from 1 to 100,000,000. Individual percentage inputs allow 0–20%; this is a computational bound, not a market benchmark. Per-transaction fees allow 0–1,000,000, fixed/additional monthly fees 0–1 billion and statement total fees 0–1 trillion. Numeric strings are limited to 32 characters; finite combined money, ratios and estimated counts are limited to 1 quadrillion. Invalid active values suppress results and disable copy/print. Inactive statement or plan fields are not required. Currency selection changes symbols only, with no FX conversion. Internal arithmetic retains full precision; money, effective rates and average tickets display two decimals normally, while tiny nonzero values retain meaningful digits.
Average interchange is a user-entered assumed or observed average, not a universal rate. Actual interchange can vary by card type, brand, rewards tier, transaction type, acceptance method, merchant category, card mix and other network/payment characteristics.
Educational fee estimate based only on entered pricing and volumes. Unentered assessments, network charges, AVS, batch, PCI, chargeback, cross-border and other fees are not modeled. Actual pricing and terms vary by country and provider. Lower modeled cost is not a processor recommendation or guaranteed savings. Annualized estimates assume the same monthly inputs for 12 months.
No processor rankings, provider recommendations, interchange-category database, card-network fee database, statement parser, merchant account system, tax model or FX conversion. Inputs remain local with no accounts, storage, saved statements, URL persistence, network calculations or user-input analytics payloads. Refresh restores defaults.
FAQ
How do I calculate merchant processing fees?
Multiply processed volume by each entered percentage rate, add transaction count multiplied by each per-transaction fee, then add fixed and enabled additional monthly charges.
What is a flat-rate processing plan?
This model uses one entered percentage of volume plus a per-transaction charge and any entered monthly fees. It does not infer a processor’s actual terms.
What is interchange-plus pricing?
Here it means an entered average interchange percentage plus separate processor percentage and per-transaction markups, with entered monthly charges. Actual card-level interchange and network fees are not calculated.
What is an effective processing rate?
It is total modeled or entered processing fees divided by processed volume, multiplied by 100. It summarizes costs rather than identifying individual charges.
How does average transaction size affect processing fees?
Smaller tickets mean more transactions for the same volume, making per-transaction fees a larger share of processing cost.
How do I calculate the break-even point between two processing plans?
Hold average ticket constant, add percentage rates and per-transaction fee divided by ticket to get each variable slope, then divide the fixed-fee difference by the slope difference. A positive threshold is shown only when the algebra supports one.
Why can average interchange vary?
Card type, brand, rewards tier, transaction type, acceptance method, merchant category, card mix and other payment characteristics can affect it. The entered average is an assumption, not a universal rate.
How do I calculate my effective rate from a processor statement?
Enter total processing fees and processed volume from the same period; divide fees by volume and multiply by 100. Enter transactions only if needed for per-transaction comparisons.
How do I estimate annual processing-fee savings?
Multiply modeled monthly savings by 12. This is an annualized estimate assuming the same monthly volume, ticket mix, rates and fees.
Does the cheaper modeled plan always mean I should switch processors?
No. The comparison covers entered fees only; actual service, contracts, features, unentered charges and changing card mix matter. It does not recommend a provider or guarantee savings.
Sources
Model and definitions reviewed 2026-10-04. Visa explains interchange terminology and distinguishes bank-to-bank interchange from merchant pricing. Stripe documentation describes pricing-structure concepts; advertised provider rates are not used as universal benchmarks. The calculator’s effective-rate, break-even and annualization formulas follow the supplied fee model and disclosed assumptions. Sources do not endorse BuzCalculator.