19 May 2026 · The Payments Expert
Shopify Payments — the math past £10k a month
We already wrote about the headline saving when moving off Shopify Payments. This is the deeper version — what an interchange-plus statement actually looks like for a Shopify merchant at £30k, £60k and £120k monthly card volume.
We've written before about why Shopify Payments quietly costs you 25–45% more than it should once you cross £10k a month on cards. That post is the headline. This is the math.
If you are running a Shopify store and your monthly card volume is solid, you almost certainly are reading a statement that hides the cliff edge. The blended rate is fine. The line-by-line numbers are not.
The flat-rate trap
Shopify Payments quotes a flat all-in rate — somewhere in the 1.4–1.7% range for UK cards depending on plan tier. At £2,000 a month in card volume, that's £30–35 in fees. The convenience is worth it.
At £30,000 a month, the same flat 1.5% is £450 in monthly fees. The convenience hasn't grown. The bill has.
The reason it stings more at scale is interchange. Most of your real-world card mix — UK consumer debit, UK consumer credit, contactless — has a real underlying interchange cost between 0.2% and 0.3%. Shopify is charging you a flat 1.5% over the top of that. That gap is the markup, and the gap is fixed regardless of how cheap the underlying card is.
An interchange-plus deal exposes that gap. You pay the real cost of each card plus a fixed acquirer markup, which for a Shopify-sized merchant lands in the 0.25–0.45% range. The flat-rate quote stops looking like a courtesy and starts looking like a tax.
A worked example
Let's take a fairly typical Shopify storefront doing £30,000 a month on cards. Assume the card mix is roughly 70% UK consumer debit, 20% UK consumer credit, 8% UK commercial cards, 2% international.
On Shopify Payments at a blended 1.5%:
- Monthly fees: ~£450
- Annualised: ~£5,400
On an interchange-plus deal at IC + 0.35%:
- 70% × (0.20% + 0.35%) = 0.385%
- 20% × (0.30% + 0.35%) = 0.130%
- 8% × (1.50% + 0.35%) = 0.148%
- 2% × (1.90% + 0.35%) = 0.045%
- Effective rate: ~0.71%
- Monthly fees: ~£213
- Annualised: ~£2,556
That's a £2,800 annual saving on a £360k turnover merchant. The numbers above are illustrative — real card-type mix from your statement will move them — but the shape holds.
At £60k a month the saving roughly doubles. At £120k a month it quadruples, and you start to recover a year's salary for whoever runs your operations.
The platform tax you're paying separately
There's a second line of cost that the rate comparison above doesn't even touch. Shopify Payments is not just an acquirer; it's a platform fee. The percentage you pay Shopify includes a margin Shopify takes for owning the checkout stack. If you switch off Shopify Payments and use a third-party gateway, Shopify charges an additional Shopify Plan transaction fee (0.5–2% depending on plan).
That fee makes the switch look more expensive than it actually is. Two things to know:
- The Shopify transaction fee is fixed by plan, not by gateway. Moving from Basic to Shopify or to Advanced reduces it. Most merchants past £10k/month justify the plan upgrade purely from this fee differential.
- The combined cost of an interchange-plus acquirer plus the Shopify Plan transaction fee is still meaningfully lower than Shopify Payments at scale. We model both sides when quoting, with the Shopify transaction fee included.
What we'd ask for
The thing that turns an estimate into a quote is a recent month's payouts report from Shopify and the corresponding Shopify Payments fee breakdown. That gives us the real card mix and the actual platform fee level. From there a like-for-like model is a working day's work, and you get a quote that survives the accountant.