Codex 5.4 vs 5.5 pricing and quality

A developer tested GPT 5.4 and GPT 5.5 across four prompt detail levels, finding that GPT 5.4 with a highly detailed prompt achieves results nearly as good as GPT 5.5. The best GPT 5.4 output scored 9.0/10, close to GPT 5.5's top score of 9.4/10, offering a lower-cost alternative with minimal quality loss.

You can get very close results to GPT 5.5 by using GPT 5.4 with a highly detailed prompt . I ran a small test to check this properly. I generated the same technical content into summaries using both GPT 5.4 and GPT 5.5, across four different prompt detail levels Low to XHigh . Then I asked ChatGPT to rank all 8 outputs blindly, without giving it any scoring categories or guidelines — so my own preferences wouldn’t influence the result. Here’s how it turned out: Rankings 1 = best : GPT 5.5 XHigh — 9.4/10 Best overall balance of technical depth, accuracy, and framing. GPT 5.4 XHigh — 9.0/10 Extremely close to the top. Clean, well-structured, and strong. GPT 5.4 High — 8.7/10 Solid and grounded, with good references to the source material. GPT 5.5 Medium — 8.5/10 GPT 5.5 High — 8.5/10 Both clear and reliable. GPT 5.5 Low — 8.3/10 Held up surprisingly well for a lighter prompt. GPT 5.4 Medium — 8.0/10 GPT 5.4 Low — 7.6/10 Main takeaway: Once you go all-in on prompt detail XHigh , the performance gap between 5.4 and 5.5 becomes quite small. This gives you a practical, lower-cost option without losing much quality.