Pick Claude Haiku 4.5 for fastest claude model or low-latency, high-volume api calls. Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. On a tight budget at scale, Claude Haiku 4.5 is the value pick.
Claude Haiku 4.5 (Anthropic) and GPT-5.3-Codex (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Haiku 4.5 is anthropic's fastest, most compact model — built for speed and volume. GPT-5.3-Codex is openAI's coding-specialized agent model for autonomous software engineering. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences
Price: Claude Haiku 4.5 is about 1.8× cheaper on input ($1/$5 per 1M tokens vs $1.75/$14 per 1M tokens) — modest, but it adds up at steady volume.
Context window: GPT-5.3-Codex holds 2× more — 400K (~600 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
Recency: GPT-5.3-Codex is the newer model by about 4 months (released February 24, 2026), usually meaning fresher training data and capabilities.
Specifications
Spec
Claude Haiku 4.5
GPT-5.3-Codex
Provider
Anthropic (US)
OpenAI (US)
Released
October 15, 2025
February 24, 2026
Context window
200K (~300 pages)
400K (~600 pages)
Price (in/out)
$1/$5 per 1M tokens
$1.75/$14 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Fastest Claude model: Claude Haiku 4.5 — Anthropic's fastest, most compact model — built for speed and volume — and it runs cheaper at $1/$5 per 1M tokens.
Low-latency, high-volume API calls: Claude Haiku 4.5 — At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex ($1.75/$14 per 1M tokens), and that gap compounds at volume.
Real-time interactions: Claude Haiku 4.5 — Claude Haiku 4.5 lists real-time interactions among its strengths; GPT-5.3-Codex does not.
Dedicated coding agent: GPT-5.3-Codex — OpenAI's coding-specialized agent model for autonomous software engineering — and it carries the larger 400K context.
CLI and IDE integration: GPT-5.3-Codex — OpenAI's coding-specialized agent model for autonomous software engineering — and it is the newer of the two.
Autonomous software tasks: GPT-5.3-Codex — GPT-5.3-Codex lists autonomous software tasks among its strengths; Claude Haiku 4.5 does not.
Lowest cost at scale: Claude Haiku 4.5 — At $1/$5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input: GPT-5.3-Codex — Its 400K window is about 2× larger than Claude Haiku 4.5's 200K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume: Claude Haiku 4.5 — At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases: GPT-5.3-Codex — Larger 400K window fits more in one prompt.
Anyone whose priority is fastest claude model: Claude Haiku 4.5 — It is specifically built for that.
Anyone whose priority is dedicated coding agent: GPT-5.3-Codex — That is its strongest area.
Claude Haiku 4.5: where it fits
Anthropic's fastest, most compact model — built for speed and volume. Released October 15, 2025 by Anthropic, it is built for fastest Claude model, low-latency, high-volume API calls, real-time interactions, and cheapest Claude tier.
Its trade-offs are real: smallest context in the family (200K), and not for deep reasoning. At $1 in / $5 out per million tokens, it sits in the budget price band.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released February 24, 2026 by OpenAI, it is built for dedicated coding agent, cLI and IDE integration, autonomous software tasks, and tool calling.
Its trade-offs: coding-specialized, narrower general use, and retired in favor of GPT-5.5 Codex. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Haiku 4.5 and GPT-5.3-Codex overlap enough that the right pick depends on your specific job. Claude Haiku 4.5 costs less per token; GPT-5.3-Codex holds the larger context; and each leads in its own area — Claude Haiku 4.5 for fastest claude model, GPT-5.3-Codex for dedicated coding agent. Rather than crowning one, run the same hard task through both once and let the results decide.
Frequently asked questions
Is Claude Haiku 4.5 or GPT-5.3-Codex better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Haiku 4.5 leans toward fastest claude model while GPT-5.3-Codex leans toward dedicated coding agent, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Haiku 4.5 or GPT-5.3-Codex?
Claude Haiku 4.5 is cheaper — $1/$5 per 1M tokens vs $1.75/$14 per 1M tokens, roughly 1.8× apart on input.
Which has the bigger context window?
GPT-5.3-Codex — 400K vs 200K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Haiku 4.5 and GPT-5.3-Codex together?
Yes — a multi-model platform like LumiChats gives you Claude Haiku 4.5, GPT-5.3-Codex and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Haiku 4.5 or GPT-5.3-Codex?
GPT-5.3-Codex — released February 24, 2026, about 4 months after Claude Haiku 4.5.
Claude Haiku 4.5 vs GPT-5.3-Codex
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Haiku 4.5 for fastest claude model or low-latency, high-volume api calls. Pick GPT-5.3-Codex for dedicated coding agent or cli and ide integration. On a tight budget at scale, Claude Haiku 4.5 is the value pick.
Claude Haiku 4.5 (Anthropic) and GPT-5.3-Codex (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Haiku 4.5 is anthropic's fastest, most compact model — built for speed and volume. GPT-5.3-Codex is openAI's coding-specialized agent model for autonomous software engineering. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
▸Price: Claude Haiku 4.5 is about 1.8× cheaper on input ($1/$5 per 1M tokens vs $1.75/$14 per 1M tokens) — modest, but it adds up at steady volume.
▸Context window: GPT-5.3-Codex holds 2× more — 400K (~600 pages) vs 200K (~300 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
▸Recency: GPT-5.3-Codex is the newer model by about 4 months (released February 24, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
Spec
Claude Haiku 4.5
GPT-5.3-Codex
Provider
Anthropic (US)
OpenAI (US)
Released
October 15, 2025
February 24, 2026
Context window
200K (~300 pages)
400K (~600 pages)
Price (in/out)
$1/$5 per 1M tokens
$1.75/$14 per 1M tokens
Open weight?
No — API only
No — API only
Modalities
text, image, code
text, code
SWE-Bench Verified
Not published
Not published
MRCR v2 @ 1M
Not published
Not published
Who wins what
Fastest Claude model
Claude Haiku 4.5
Anthropic's fastest, most compact model — built for speed and volume — and it runs cheaper at $1/$5 per 1M tokens.
Low-latency, high-volume API calls
Claude Haiku 4.5
At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex ($1.75/$14 per 1M tokens), and that gap compounds at volume.
Real-time interactions
Claude Haiku 4.5
Claude Haiku 4.5 lists real-time interactions among its strengths; GPT-5.3-Codex does not.
Dedicated coding agent
GPT-5.3-Codex
OpenAI's coding-specialized agent model for autonomous software engineering — and it carries the larger 400K context.
CLI and IDE integration
GPT-5.3-Codex
OpenAI's coding-specialized agent model for autonomous software engineering — and it is the newer of the two.
Autonomous software tasks
GPT-5.3-Codex
GPT-5.3-Codex lists autonomous software tasks among its strengths; Claude Haiku 4.5 does not.
Lowest cost at scale
Claude Haiku 4.5
At $1/$5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
GPT-5.3-Codex
Its 400K window is about 2× larger than Claude Haiku 4.5's 200K, fitting roughly 600 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Claude Haiku 4.5
At $1/$5 per 1M tokens it undercuts GPT-5.3-Codex, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ GPT-5.3-Codex
Larger 400K window fits more in one prompt.
Anyone whose priority is fastest claude model
→ Claude Haiku 4.5
It is specifically built for that.
Anyone whose priority is dedicated coding agent
→ GPT-5.3-Codex
That is its strongest area.
Claude Haiku 4.5: where it fits
Anthropic's fastest, most compact model — built for speed and volume. Released October 15, 2025 by Anthropic, it is built for fastest Claude model, low-latency, high-volume API calls, real-time interactions, and cheapest Claude tier.
Its trade-offs are real: smallest context in the family (200K), and not for deep reasoning. At $1 in / $5 out per million tokens, it sits in the budget price band.
GPT-5.3-Codex: where it fits
OpenAI's coding-specialized agent model for autonomous software engineering. Released February 24, 2026 by OpenAI, it is built for dedicated coding agent, cLI and IDE integration, autonomous software tasks, and tool calling.
Its trade-offs: coding-specialized, narrower general use, and retired in favor of GPT-5.5 Codex. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Haiku 4.5 and GPT-5.3-Codex overlap enough that the right pick depends on your specific job. Claude Haiku 4.5 costs less per token; GPT-5.3-Codex holds the larger context; and each leads in its own area — Claude Haiku 4.5 for fastest claude model, GPT-5.3-Codex for dedicated coding agent. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Haiku 4.5 and GPT-5.3-Codex without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
Is Claude Haiku 4.5 or GPT-5.3-Codex better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Haiku 4.5 leans toward fastest claude model while GPT-5.3-Codex leans toward dedicated coding agent, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Haiku 4.5 or GPT-5.3-Codex?
Claude Haiku 4.5 is cheaper — $1/$5 per 1M tokens vs $1.75/$14 per 1M tokens, roughly 1.8× apart on input.
Which has the bigger context window?
GPT-5.3-Codex — 400K vs 200K, about 2× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Haiku 4.5 and GPT-5.3-Codex together?
Yes — a multi-model platform like LumiChats gives you Claude Haiku 4.5, GPT-5.3-Codex and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Haiku 4.5 or GPT-5.3-Codex?
GPT-5.3-Codex — released February 24, 2026, about 4 months after Claude Haiku 4.5.
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.