What this comparison can—and cannot—tell you
The calculator applies the requested percentage change and the official sector percentage change independently to the same starting annual cost. Their difference is financial context for a negotiation, not an achieved reduction or independently determined fair price.
A logistics supplier may legitimately face different fuel costs, route mixes or service levels from the aggregate road-freight index. A cleaning contract may include increased labour hours even when the unit price has barely moved. Normalise the specification first.
Turn the result into useful commercial questions
Ask the incumbent to separate labour, materials, operating scope, surcharge changes and supplier margin. Request the actual index and observation period stated in the contract. Test a comparable alternative on total delivered cost, including transition and ongoing management costs.
Then ensure your finance team records any signed amendments and validates the resulting invoices. The difference between quotations is not automatically a realised procurement saving. See our supplier negotiation process, savings methodology and CFO worksheet.
Where the numbers originate
Sector changes come from five separately linked ONS Services Producer Price Index series for 2026 Q2, compared with 2025 Q2. Indices use a 2015=100 basis and may be revised. Reused under the Open Government Licence v3.0; ONS does not endorse the analysis or this consultancy.