Is Amazon Web Services (AWS) Doing Your Currency Conversions (and Costing You Millions)?

If your UK business pays for AWS, it’s worth pulling up a chair, because what may look like routine dollar-to-pound billing could actually be hiding a hefty, and wholly unnecessary, currency-conversion fee. The Stable team recently came across a real-world client example that highlights a common but often overlooked cost sink, which we’ll set out below.

The Cost Issue: Invisible Exchange-Rate Margin

Here’s the loop: for many UK businesses, AWS billing defaults to sterling (GBP) but AWS originates its invoices in US dollars. At month-end, AWS applies its own exchange rate to convert the invoice back into GBP. For one client, when we dug into their invoice history, the extra margin baked into that conversion added up to £22,500… in one month! That’s not a rounding error. That’s a material cash leak.

The Root Cause: Default Billing and No Escape Hatch

The issue isn’t a bug by any stretch, it’s by design. Most UK corporates don’t challenge default currency settings, they just pay what lands in their inbox. The result of this is you end up paying twice - first for your AWS usage, then for an opaque ‘exchange-rate conversion service.’ For any sizeable AWS spend, that’s a non-trivial sum, especially in the current challenging macro-economic climate for UK businesses, many of whom are looking for ways to slash costs.

A Smarter Way: USD Cards & USD Wallets

Here’s how the client resolved it and how you could too. They moved to a payment provider that supports both:

• A USD-denominated card (virtual or physical), plus
• A USD wallet, pre-loaded ahead of invoicing

This way, the business can choose when and how to convert its sterling, converting when FX rates are favourable, storing USD in the wallet, and then using those dollars to pay AWS invoices directly. No surprise mark-ups, just transparent FX execution.

Why This Matters for UK SMEs

For many UK SMEs (especially those with recurring cloud spend, international operations, or multi-country cost bases), this simple FX approach can slash unnecessary overhead. If your hidden margin is anything close to our client’s at around £22.5k a month, annualised, that’s over a quarter of a million pounds. And CFOs, FDs and FCs have the opportunity to be the hero and squash that costly gremlin.

It’s not just about cost, it's also about visibility and control. When exchange costs are baked into a single GBP invoice, they hide in plain sight. But when you start managing currencies proactively, which can include choosing when to convert, when to hold dollars, paying invoices with USD, suddenly your cloud spend budgeting becomes far more predictable.

Moreover, handling currency cleanly can also help with forecasting, debt covenants, and cash-flow forecasting, especially for businesses with multi-currency revenue or expenses (common in UK SMEs selling or buying internationally).

What CFOs & Finance Teams Should Do This Quarter

• Audit your AWS (and other cloud) spend currency flows. If invoices are generated in USD and converted to GBP — calculate the FX margin you’ve paid over the last 6–12 months.
• Explore card/wallet providers that support USD cards and USD wallets, especially those tailored for businesses.
• Consider a policy update: For any recurring USD-invoiced vendors (AWS, cloud infrastructure services, international SaaS), mandate USD settlement and/or pre-loading USD wallets.
• Build FX execution into your cloud-cost and procurement process to lock in favourable rates, control conversion timing, and boost transparency.

If you're not sure where to start, the team at Stable are on hand to help, both in quantifying the current conversion costs for your business but also in connecting you with the right solutions to optimise your AWS cost settlements. Drop us an email at info@stablepayments.co.uk or click 'Get Started' at the top of the page.