ZMIME
Comparison · 2 models · Updated Oct 4, 2026

GPT-5.4 Pro vs GPT-5.5 Pro

GPT-5.5 Pro comes out ahead, 65 to 60 on our weighted score.

  1. OpenAI

    GPT-5.4 Pro

    Released Mar 5, 2026

    60/100
    • ECI159.1
    • Price$30.00 / $180.00
    • Context1.05M
    Full specs Remove GPT-5.4 Pro
  2. Our pick

    OpenAI

    GPT-5.5 Pro

    Released Apr 23, 2026

    65/100
    • ECI162.4
    • Price$30.00 / $180.00
    • Context1.05M
    Full specs Remove GPT-5.5 Pro

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-5.5 Pro is our pick

GPT-5.5 Pro is the better all-round choice, scoring 65/100 against GPT-5.4 Pro (60). It leads on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGPT-5.5 ProCapabilities Index (ECI): GPT-5.5 Pro 162.4 · GPT-5.4 Pro 159.1
  • Lowest priceSame priceGPT-5.4 Pro $67.50 · GPT-5.5 Pro $67.50 per 1M tokens (3:1 blend)
  • Longest contextAbout the sameGPT-5.4 Pro 1,050,000 · GPT-5.5 Pro 1,050,000 tokens
  • Widest inputsGPT-5.5 ProGPT-5.4 Pro: Text, Images · GPT-5.5 Pro: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.4 ProGPT-5.5 Pro
CapabilityCapabilities Index (ECI)50%9094
Price25%00
Inputs & features15%6080
Context window10%6161
Overall100%60/10065/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

GPT-5.4 Pro vs GPT-5.5 Pro specifications side by side
SpecificationGPT-5.4 ProOpenAIGPT-5.5 ProOpenAI
Capability
Capabilities Index (ECI)159.1162.4 (best)
ECI rank#11 of 148#6 of 148 (best)
GPQA DiamondGraduate-level science questions94.6% (best)93.9%
FrontierMath Tiers 1–3Research-level mathematics82.5%87.7% (best)
OTIS Mock AIME 2024–2025Competition mathematics—100%
SimpleQA VerifiedShort factual questions46.3%—
Price per million tokens
Input$30.00$30.00
Output$180.00$180.00
Cached input——
Blended (3:1)$67.50$67.50
Long-context rateOver 272K: $60.00 / $270.00Over 272K: $60.00 / $270.00
Price sourceOfficial OpenAI APIOfficial OpenAI API
Limits
Context window1,050,000 tokens1,050,000 tokens
Max output128,000 tokens128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYesmedium · high · xhighYesmedium · high · xhigh
Tool callingYesYes
Structured outputNoYes
Availability
WeightsProprietaryProprietary
API model IDgpt-5.4-progpt-5.5-pro
API providers1619 (best)
ReleasedMar 5, 2026Apr 23, 2026
Knowledge cutoffAug 31, 2025Dec 1, 2025
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • GPT-5.4 Pro$660.00
  • GPT-5.5 Pro$660.00
04 — Questions

Which should you choose?

Which is better: GPT-5.4 Pro or GPT-5.5 Pro?

GPT-5.5 Pro is the better all-round choice, scoring 65/100 against GPT-5.4 Pro (60). It leads on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, GPT-5.4 Pro or GPT-5.5 Pro?

GPT-5.4 Pro and GPT-5.5 Pro cost the same: $30.00 input / $180.00 output per million tokens.

Which scores higher on benchmarks?

GPT-5.5 Pro scores higher on the Capabilities Index (ECI): GPT-5.5 Pro 162.4 (#6 of 148) and GPT-5.4 Pro 159.1 (#11 of 148). The confidence ranges of the top two overlap (159.0–166.0 vs 156.5–161.9), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-5.4 Pro 94.6%, GPT-5.5 Pro 93.9%; FrontierMath Tiers 1–3 — GPT-5.5 Pro 87.7%, GPT-5.4 Pro 82.5%.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-5.4 Pro and GPT-5.5 Pro yet, so there is no like-for-like coding score. On overall capability, GPT-5.5 Pro leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.4 Pro and GPT-5.5 Pro share the same 1,050,000-token context window. Maximum output per response: GPT-5.4 Pro up to 128,000, GPT-5.5 Pro up to 128,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.4 Pro accepts text and images; GPT-5.5 Pro accepts text, images and PDFs. GPT-5.5 Pro handles the widest range of inputs.

Are any of these open source?

No. GPT-5.4 Pro and GPT-5.5 Pro are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.5 Pro is the newest, released Apr 23, 2026. GPT-5.4 Pro came out Mar 5, 2026. Knowledge cutoff: GPT-5.4 Pro Aug 31, 2025, GPT-5.5 Pro Dec 1, 2025.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

Related comparisons