Payment processing costs vary dramatically depending on which processor you use, how you’re billed (flat-rate vs interchange-plus), your monthly volume, and your average transaction size. This guide gives you the numbers to compare processors side by side on your actual business profile — so you can calculate the annual cost difference before you switch.
ConvesioPay’s interchange++ pricing consistently outperforms flat-rate processors at WooCommerce volumes. Get started →
1. The Cost Comparison Formula
To compare two processors fairly, you need to calculate total annual cost — not just compare percentage rates:
Annual Cost = (Monthly Volume × Rate%) + (Monthly Transactions × Per-Transaction Fee) + (Monthly Fixed Fees × 12)
Then compare on an apples-to-apples basis using your same volume inputs.
2. Annual Cost Comparison by Volume
At $50,000/year (small store)
Assumptions: 500 transactions/year, $100 average order value, standard card mix
| Processor | Rate | Transaction Fees | Monthly Fees | Est. Annual Cost |
|---|---|---|---|---|
| Stripe | 2.9% | $0.30/txn | $0 | $1,600 |
| PayPal | 3.49% | $0.49/txn | $0 | $1,990 |
| Square | 2.9% | $0.30/txn | $0 | $1,600 |
| Authorize.net | 2.9% | $0.30/txn | $25/month | $1,900 |
| ConvesioPay | ~1.8% avg | $0.10/txn | $0 | $950 |
At $150,000/year (mid-size store)
Assumptions: 1,500 transactions/year, $100 average order value
| Processor | Est. Annual Cost | vs. ConvesioPay |
|---|---|---|
| Stripe | $4,800 | +$2,070 |
| PayPal | $5,970 | +$3,240 |
| Square | $4,800 | +$2,070 |
| Authorize.net | $5,100 | +$2,370 |
| ConvesioPay | $2,730 | — |
At $500,000/year (high-volume store)
Assumptions: 5,000 transactions/year, $100 average order value
| Processor | Est. Annual Cost | vs. ConvesioPay |
|---|---|---|
| Stripe | $16,000 | +$6,900 |
| PayPal | $19,900 | +$10,800 |
| Square | $16,000 | +$6,900 |
| Authorize.net | $16,800 | +$7,700 |
| ConvesioPay | $9,100 | — |
Note: ConvesioPay costs are estimates based on average interchange. Actual costs vary by card type mix. Interchange-plus savings are highest when your customers use more debit cards and non-rewards credit cards.
3. How Pricing Model Affects Your Cost
Flat-Rate Pricing
Stripe, PayPal, and Square use flat-rate pricing: one rate regardless of card type. Simple to understand, but you pay the same rate on cheap debit cards as you do on expensive premium rewards cards. The processor keeps the difference. Flat-rate is cost-effective only for very low-volume merchants (under ~$5,000/month) where simplicity has more value than savings.
Interchange-Plus Pricing
Interchange-plus passes the actual interchange cost through to you at cost, then charges a separate, transparent markup. You pay different rates for different card types. This means you’re never overpaying on cheap cards — and you can see exactly where every fee goes. Merchants switching to interchange++ save an average 0.38% of processing volume (ConvesioPay Q1 2026 Report).
Tiered Pricing (Avoid)
Some traditional processors use tiered pricing (qualified/mid-qualified/non-qualified), which is opaque and nearly always more expensive than interchange-plus. Most transactions get classified as “non-qualified” (highest tier) by design. If a processor quotes you tiered pricing, request interchange-plus instead or switch processors.
4. Factors That Change Your Cost
Several factors affect your actual processing cost regardless of the rate you’re quoted:
- Card mix — more debit card transactions lower your cost significantly; more premium rewards cards raise it. If 30% of your customers pay with debit, you should be on interchange-plus to capture that savings
- Average ticket size — low-ticket merchants (under $15) should prioritize lower per-transaction fees; high-ticket merchants should focus on the percentage rate
- International customers — cross-border transactions carry a 0.4–1.5% surcharge from the card networks, regardless of your processor
- Card-not-present vs. card-present — online transactions (card-not-present) carry higher interchange than in-person transactions
- Monthly volume consistency — some processors charge monthly minimums if you don’t process enough volume
5. The Break-Even Analysis: Flat-Rate vs Interchange-Plus
The break-even point where interchange-plus becomes cheaper depends on your card mix and volume. For most e-commerce merchants with standard card mixes:
- Under $3,000/month — flat-rate simplicity may be worth the slight premium
- $3,000–$10,000/month — interchange-plus typically saves $50–$300/month
- Over $10,000/month — interchange-plus savings are significant; staying on flat-rate is a material cost that compounds annually
For a complete breakdown of fee structures, see Credit Card Processing Fees Explained: What You’re Really Paying. For a detailed guide to reading your current statement, see Merchant Statement Analysis: How to Read and Audit Your Processing Statement.
Compare your current processing cost against ConvesioPay. Most WooCommerce merchants save $1,500–$8,000 per year by switching to interchange++ pricing. Get started →