The verdict in three sentences
Integrating full online payment (card, SEPA transfer, instalments) on an SME's site costs between 5,000 and 18,000 EUR in 2026, over a 3 to 6 week timeline. The real recurring cost is not the integration but the PSP fees: 1.2 to 2.5% + 0.25 EUR per transaction. Instalment payment has a cost but can raise conversion and average basket by 20 to 30%.
What integration and PSP fees cost
Integration is a one-off cost; fees are a permanent cost weighing on every sale. Here are the 2026 ballpark figures for the main PSPs for an SME.
| PSP | Card fee | Fixed fee / transaction | SEPA transfer |
|---|---|---|---|
| Stripe | 1.4% + 0.25 EUR | Included | 0.8% (capped) |
| Mollie | 1.2% + 0.25 EUR | Included | 0.25 EUR |
| PayPlug | 1.2 - 2.5% + 0.25 EUR | Included | On quote |
| Adyen | Interchange + 0.10 EUR | By volume | Included |
| Lyra / Systempay | 0.9% + monthly fee | 0.10 EUR | Included |
For a high-volume SME, an interchange + fixed PSP (Adyen) becomes cheaper; for modest volume, Stripe or Mollie remain the simplest to integrate.
Instalment payment and its conversion impact
Instalment payment (3x, 4x) has become a standard, especially on high baskets. It has a cost but unlocks sales. Here is the trade-off.
| Metric | Without instalments | With instalments |
|---|---|---|
| Instalment PSP cost | 0% | 1.5 - 4% / order |
| Conversion rate | 2.2% | 2.7 - 2.9% |
| Average basket | 140 EUR | 175 - 190 EUR |
| Abandonment at payment step | 28% | 19% |
| Settlement time | Immediate | Immediate (guaranteed) |
| Default risk | Seller | PSP (guaranteed) |
The 1.5 to 4% surcharge is often offset by the higher average basket and conversion rate. On a 175 EUR basket, 4% fee is 7 EUR, easily absorbed by the 35 EUR of extra basket.
Mini case study
Julie runs an SME selling professional furniture in Toronto, 40 orders/day, average basket 150 EUR. She integrates card, SEPA and 4x instalments for 11,000 EUR.
Before, her conversion rate capped at 2.2%. After adding instalment payment, it rises to 2.8% and the average basket to 182 EUR. On 40 orders/day, that is about 8 extra orders a day and revenue up about 32%. Even paying 3% instalment fee, the net gain covers the integration in under two months.
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FAQ
Which PSP should an SME choose in 2026?
For modest volume, Stripe or Mollie (1.2 to 1.4% + 0.25 EUR) are simplest. For high volume, Adyen on interchange + fixed becomes cheaper. The choice depends on volume and desired payment methods.
How much does the technical integration cost?
Between 5,000 and 18,000 EUR depending on the number of payment methods, webhook handling, accounting reconciliation and testing. A simple standard Stripe integration stays at the low end.
Is instalment payment worth the cost?
Yes in most cases: it costs 1.5 to 4% per order but raises conversion by 20 to 30% and the average basket. The PSP guarantees settlement and carries the default risk.
Do I need SEPA transfer for B2B?
Yes, in B2B many customers pay by transfer. SEPA costs little (0.25 EUR or 0.8% capped) and avoids the card fee on large amounts.
How long to set up?
Expect 3 to 6 weeks: integration, webhook configuration, end-to-end testing and acceptance before going live.
Let's scope your project. Tell us your desired payment methods, your order volume and your average basket, and we will price your payment integration. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
