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Comparison · 2 models · Updated Oct 4, 2026

GPT-5.3 Codex vs GPT-6.1 Sol

GPT-6.1 Sol comes out ahead, 47 to 42 on our weighted score, and it is the cheaper option too.

  1. OpenAI

    GPT-5.3 Codex

    Released Feb 5, 2026

    42/100
    • ECI156.8
    • Price$1.75 / $14.00
    • Context400K
    Full specs Remove GPT-5.3 Codex
  2. Our pick

    OpenAI

    GPT-6.1 Sol

    Released Sep 29, 2026

    47/100
    • ECI—
    • Price$2.00 / $10.00
    • Context1.05M
    Full specs Remove GPT-6.1 Sol

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

GPT-6.1 Sol is our pick

GPT-6.1 Sol is the better all-round choice, scoring 47/100 against GPT-5.3 Codex (42). It leads on price and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

  • CapabilityNot enough dataNo independent benchmark covers every model here yet
  • Lowest priceGPT-6.1 SolGPT-6.1 Sol $4.00 · GPT-5.3 Codex $4.81 per 1M tokens (3:1 blend)
  • Longest contextGPT-6.1 SolGPT-6.1 Sol 1,050,000 · GPT-5.3 Codex 400,000 tokens
  • Widest inputsSame inputsGPT-5.3 Codex: Text, Images, PDFs · GPT-6.1 Sol: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGPT-5.3 CodexGPT-6.1 Sol
Price50%1821
Inputs & features30%8080
Context window20%4461
Overall100%42/10047/100

Left out because at least one model lacks the data: capability. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

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

GPT-5.3 Codex vs GPT-6.1 Sol specifications side by side
SpecificationGPT-5.3 CodexOpenAIGPT-6.1 SolOpenAI
Capability
Capabilities Index (ECI)156.8—
ECI rank#18 of 148—
GPQA DiamondGraduate-level science questions—95.4%
FrontierMath Tiers 1–3Research-level mathematics—93.7%
OTIS Mock AIME 2024–2025Competition mathematics—100%
SWE-bench VerifiedFixing real GitHub issues74.8%—
SimpleQA VerifiedShort factual questions—73.9%
Price per million tokens
Input$1.75 (best)$2.00
Output$14.00$10.00 (best)
Cached input$0.175$0.10 (best)
Blended (3:1)$4.81$4.00 (best)
Long-context rateSame rateOver 272K: $4.00 / $15.00
Price sourceOfficial OpenAI APIOfficial OpenAI API
Limits
Context window400,000 tokens1,050,000 tokens (best)
Max output128,000 tokens128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhighYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgpt-5.3-codexgpt-6.1-sol
API providers1921 (best)
ReleasedFeb 5, 2026Sep 29, 2026
Knowledge cutoffAug 31, 2025Apr 30, 2026
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-5.3 Codex$45.50
  • GPT-6.1 Sol$40.00
04 — Questions

Which should you choose?

Which is better: GPT-5.3 Codex or GPT-6.1 Sol?

GPT-6.1 Sol is the better all-round choice, scoring 47/100 against GPT-5.3 Codex (42). It leads on price and context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

Which is cheaper, GPT-5.3 Codex or GPT-6.1 Sol?

GPT-6.1 Sol is cheaper at $2.00 input / $10.00 output per million tokens (official OpenAI API price). GPT-5.3 Codex costs $1.75 input / $14.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6.1 Sol versus $4.81 for GPT-5.3 Codex (1.2× as much).

Which scores higher on benchmarks?

There is no independent benchmark that covers both models yet. GPT-5.3 Codex has an ECI of 156.8 and GPT-6.1 Sol has not been scored yet.

Which is better for coding?

There are no published SWE-bench Verified results for GPT-6.1 Sol yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-6.1 Sol has the largest context window at 1,050,000 tokens, against 400,000 for GPT-5.3 Codex. Maximum output per response: GPT-5.3 Codex up to 128,000, GPT-6.1 Sol up to 128,000 tokens.

Which can read images, PDFs, audio or video?

GPT-5.3 Codex accepts text, images and PDFs; GPT-6.1 Sol accepts text, images and PDFs. They handle the same number of input types.

Are any of these open source?

No. GPT-5.3 Codex and GPT-6.1 Sol are proprietary and only available through APIs and apps.

Which is newer?

GPT-6.1 Sol is the newest, released Sep 29, 2026. GPT-5.3 Codex came out Feb 5, 2026. Knowledge cutoff: GPT-5.3 Codex Aug 31, 2025, GPT-6.1 Sol Apr 30, 2026.

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

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