A cheaper token does not necessarily mean a cheaper completed task.

That remains the point of this monthly pricing watch. August is the second issue, which means we can finally make a direct comparison with July instead of treating one rate card as a trend.

The first result is pleasantly concrete. Across 20 matched provider, model, and category entries, three published provider-currency price cards changed. Seventeen did not. The pound price for the unchanged cards still moved a little because the exchange rate moved.

That is exactly why I want to keep the original provider currency next to the GBP conversion. It stops us mistaking a currency wobble for a model-price revolution.

What changed in August

OpenAI cut GPT-5.6 Luna by 80% and GPT-5.6 Terra by 20% on 30 July. Luna moved from $1.00 input and $6.00 output per million tokens to $0.20 and $1.20. Terra moved from $2.50 and $15.00 to $2.00 and $12.00. Anthropic's Claude Haiku 4.5 also moved from $1.00 and $5.00 to $0.50 and $2.50.

On the fixed reference workloads, Luna falls from about 1.19 pence to 0.24 pence, Terra falls from about 14.83 pence to 11.88 pence, and Haiku falls from about 1.11 pence to 0.56 pence. These are real provider price changes. They are not claims that any one model is automatically best for every task. Quality, latency, context, tool use, retries, cache behaviour, and task success still matter.

The other 17 matched rate cards were unchanged in their published dollar price. The Bank of England quote used here moved from GBP 0.7414 per US dollar on 16 July to GBP 0.7426 per US dollar on 6 August. For a fixed dollar price, that makes the GBP figure around 0.16% higher. It is small, but it is not a provider price increase.

A July-to-August comparison showing 20 matched model entries, three provider-currency price changes, 17 unchanged rate cards, and the separate small GBP-to-USD exchange-rate movement.
Two snapshots make a comparison, not a forecast. Provider-currency changes come before GBP conversion.

Here is the actual July-to-August cost comparison. Each line prices the same fixed, uncached reference workload in pounds. The chart uses a separate logarithmic scale for each category so low-cost models remain readable without pretending that equal vertical distances are equal cash differences.

This version corrects an earlier draft that missed OpenAI's dated 30 July announcement. The current model-specific pages confirm the new Luna and Terra rates. A generic or stale pricing view should never outrank a dated effective announcement reconciled against the current model page.

Three line charts comparing July and August 2026 GBP reference workload costs for matched quick, general, and frontier models. GPT-5.6 Luna, GPT-5.6 Terra, and Claude Haiku 4.5 fall; the other lines show only small exchange-rate movement.
July versus August GBP cost for the same normalized workloads. Gold marks the three provider-rate reductions; grey lines show exchange-rate effects only.