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Head-to-head comparison

Claude Haiku 4.5 vs GPT-5.3-Codex

Claude Haiku 4.5 (Anthropic) and GPT-5.3-Codex (OpenAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 3 September 2026

As of 3 September 2026, GPT-5.3-Codex holds the stronger ModelCap Index position (#24 vs #45); Claude Haiku 4.5 is 2.8× cheaper per output token ($5.00/1M vs $14.00/1M); and GPT-5.3-Codex offers the longer context window (400K vs 200K tokens).

Which should you choose?

Choose Claude Haiku 4.5 if…

  • API cost matters — $5.00/1M output tokens against $14.00/1M, about 2.8× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.00/1M against $1.75/1M.
  • you want provider choice — 4 listed API providers against 2.

Choose GPT-5.3-Codex if…

  • you want the stronger overall ModelCap Index position — #24 against #45 (65.4 vs 52.4 points).
  • you need the longer context window — 400K tokens against 200K.
  • you want the more recently listed model — GPT-5.3-Codex was listed 24 February 2026, Claude Haiku 4.5 15 October 2025.

Claude Haiku 4.5 vs GPT-5.3-Codex: specs, pricing and context

Specification comparison of Claude Haiku 4.5 and GPT-5.3-Codex
FieldClaude Haiku 4.5AnthropicGPT-5.3-CodexOpenAI
ModelCap Index position#45#24
Index score52.465.4
EvidenceMeasuredMeasured
Input price / 1M tokens$1.00$1.75
Output price / 1M tokens$5.00$14.00
Context window200K tokens400K tokens
Max output tokens64K128K
API providers listed42
Weight accessAPI onlyAPI only
Input modalitiesText, Image, FileText, Image, File
First listed15 October 202524 February 2026
PublisherAnthropicOpenAI

Evidence: 3 public benchmark observations across 3 boards · 1 public benchmark observation across 1 board. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Haiku 4.5 vs GPT-5.3-Codex

Public benchmark boards where Claude Haiku 4.5 or GPT-5.3-Codex has a published result
BoardClaude Haiku 4.5GPT-5.3-CodexLeads
Arena codingArena (LMArena)14811476–1485—Only one result
ARC-AGI-2ARC Prize Foundation4.0%Thinking—Only one result
AA Intelligence IndexArtificial Analysis—45.5intelligence-indexOnly one result
AA τ²-Bench TelecomArtificial Analysis—86.0%tau2-bench-telecomOnly one result
AA Humanity's Last ExamArtificial Analysis—42.5%humanitys-last-examOnly one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Claude Haiku 4.5 vs GPT-5.3-Codex: common questions

Is Claude Haiku 4.5 better than GPT-5.3-Codex?

GPT-5.3-Codex ranks higher on the ModelCap Index as of 3 September 2026: #24 against #45. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is Claude Haiku 4.5 cheaper than GPT-5.3-Codex?

Claude Haiku 4.5 is cheaper on output tokens: $5.00/1M against $14.00/1M. Input tokens are $1.00/1M for Claude Haiku 4.5 and $1.75/1M for GPT-5.3-Codex. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, Claude Haiku 4.5 or GPT-5.3-Codex?

GPT-5.3-Codex has the larger context window: 400K tokens against 200K.

Which is better for coding, Claude Haiku 4.5 or GPT-5.3-Codex?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are Claude Haiku 4.5 and GPT-5.3-Codex open-weight models?

Claude Haiku 4.5: API only. GPT-5.3-Codex: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Claude Haiku 4.5 and GPT-5.3-Codex?

ModelCap currently lists 4 API providers for Claude Haiku 4.5 and 2 for GPT-5.3-Codex, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Claude Haiku 4.5 vs GPT-5.3-Codex comparison?

Every figure comes from the sealed ModelCap dataset published 3 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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