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Comparison · 2 models · Updated Oct 4, 2026

Gemini 3 Pro Preview vs GPT-5.3 Codex

Too close to call on our weighted score (Gemini 3 Pro Preview 67, GPT-5.3 Codex 64). The right pick depends on what you value most.

  1. Google

    Gemini 3 Pro Preview

    Released Nov 18, 2025

    67/100
    • ECI153.0
    • Price$2.00 / $12.00
    • Context1.05M
    Full specs Remove Gemini 3 Pro Preview

  2. OpenAI

    GPT-5.3 Codex

    Released Feb 5, 2026

    64/100
    • ECI156.8
    • Price$1.75 / $14.00
    • Context400K
    Full specs Remove GPT-5.3 Codex

  3. Add a model

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 3 points (Gemini 3 Pro Preview 67/100, GPT-5.3 Codex 64/100), so choose by what matters most for your work: GPT-5.3 Codex for raw capability, Gemini 3 Pro Preview on price and Gemini 3 Pro Preview for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGPT-5.3 CodexCapabilities Index (ECI): GPT-5.3 Codex 156.8 · Gemini 3 Pro Preview 153.0
  • Lowest priceGemini 3 Pro PreviewGemini 3 Pro Preview $4.50 · GPT-5.3 Codex $4.81 per 1M tokens (3:1 blend)
  • Longest contextGemini 3 Pro PreviewGemini 3 Pro Preview 1,048,576 · GPT-5.3 Codex 400,000 tokens
  • Widest inputsGemini 3 Pro PreviewGemini 3 Pro Preview: Text, Images, PDFs, Audio, Video · GPT-5.3 Codex: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGemini 3 Pro PreviewGPT-5.3 Codex
CapabilityCapabilities Index (ECI)50%8287
Price25%1918
Inputs & features15%10080
Context window10%6144
Overall100%67/10064/100
02 — Side by side

Every spec in one table

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

Gemini 3 Pro Preview vs GPT-5.3 Codex specifications side by side
SpecificationGemini 3 Pro PreviewGoogleGPT-5.3 CodexOpenAI
Capability
Capabilities Index (ECI)153.0156.8 (best)
ECI rank#39 of 148#18 of 148 (best)
GPQA DiamondGraduate-level science questions92.6%—
OTIS Mock AIME 2024–2025Competition mathematics91.4%—
SWE-bench VerifiedFixing real GitHub issues72.9%74.8% (best)
Price per million tokens
Input$2.00$1.75 (best)
Output$12.00 (best)$14.00
Cached input—$0.175
Blended (3:1)$4.50 (best)$4.81
Long-context rateSame rateSame rate
Price sourceMedian of 2 providersOfficial OpenAI API
Limits
Context window1,048,576 tokens (best)400,000 tokens
Max output65,536 tokens128,000 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioYesNo
VideoYesNo
ReasoningYesYeslow · medium · high · xhigh
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model ID—gpt-5.3-codex
API providers319 (best)
ReleasedNov 18, 2025Feb 5, 2026
Knowledge cutoffJan 2025Aug 31, 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.

  • Gemini 3 Pro Preview$44.00
  • GPT-5.3 Codex$45.50
04 — Questions

Which should you choose?

Which is better: Gemini 3 Pro Preview or GPT-5.3 Codex?

It is close. Our weighted score puts them within 3 points (Gemini 3 Pro Preview 67/100, GPT-5.3 Codex 64/100), so choose by what matters most for your work: GPT-5.3 Codex for raw capability, Gemini 3 Pro Preview on price and Gemini 3 Pro Preview for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Gemini 3 Pro Preview or GPT-5.3 Codex?

Gemini 3 Pro Preview is cheaper at $2.00 input / $12.00 output per million tokens (median across 2 API providers). 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 $4.50 per million tokens for Gemini 3 Pro Preview versus $4.81 for GPT-5.3 Codex (1.1× as much).

Which scores higher on benchmarks?

GPT-5.3 Codex scores higher on the Capabilities Index (ECI): GPT-5.3 Codex 156.8 (#18 of 148) and Gemini 3 Pro Preview 153.0 (#39 of 148). The confidence ranges of the top two overlap (153.5–160.8 vs 150.6–155.2), so treat the gap as small. On individual benchmarks: SWE-bench Verified — GPT-5.3 Codex 74.8%, Gemini 3 Pro Preview 72.9%.

Which is better for coding?

GPT-5.3 Codex resolves more real GitHub issues on SWE-bench Verified: GPT-5.3 Codex 74.8% and Gemini 3 Pro Preview 72.9%. Both support tool calling for agent workflows.

Which has the bigger context window?

Gemini 3 Pro Preview has the largest context window at 1,048,576 tokens, against 400,000 for GPT-5.3 Codex. Maximum output per response: Gemini 3 Pro Preview up to 65,536, GPT-5.3 Codex up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Gemini 3 Pro Preview accepts text, images, PDFs, audio and video; GPT-5.3 Codex accepts text, images and PDFs. Gemini 3 Pro Preview handles the widest range of inputs.

Are any of these open source?

No. Gemini 3 Pro Preview and GPT-5.3 Codex are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.3 Codex is the newest, released Feb 5, 2026. Gemini 3 Pro Preview came out Nov 18, 2025. Knowledge cutoff: Gemini 3 Pro Preview Jan 2025, GPT-5.3 Codex Aug 31, 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

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