GPT-5.3-Codex vs GPT Realtime 2
GPT-5.3-Codex (2026) and GPT Realtime 2 (2026) are agentic coding models from OpenAI. GPT-5.3-Codex ships a 400K-token context window, while GPT Realtime 2 ships a 131K-token context window. On pricing, GPT-5.3-Codex costs $1.75/1M input tokens versus $32/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
GPT-5.3-Codex is ~1729% cheaper at $1.75/1M; pay for GPT Realtime 2 only for provider fit.
Decision scorecard
Local evidence first| Signal | GPT-5.3-Codex | GPT Realtime 2 |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | RAG, Agents, and Long context |
| Context window | 400K | 131K |
| Cheapest output | $14/1M tokens | $64/1M tokens |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- GPT-5.3-Codex has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.3-Codex has the lower cheapest tracked output price at $14/1M tokens.
- GPT-5.3-Codex has broader tracked provider coverage for fallback and procurement flexibility.
- GPT-5.3-Codex uniquely exposes Vision, Structured outputs, and Code execution in local model data.
- Local decision data tags GPT-5.3-Codex for Coding, RAG, and Agents.
- GPT Realtime 2 uniquely exposes Multimodal in local model data.
- Local decision data tags GPT Realtime 2 for RAG, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
GPT-5.3-Codex
$4,900
Cheapest tracked route: OpenRouter
GPT Realtime 2
$41,600
Cheapest tracked route: OpenAI API
Estimated monthly gap: $36,700. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenAI API; start route-level A/B tests there.
- GPT Realtime 2 is $50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Vision, Structured outputs, and Code execution before moving production traffic.
- GPT Realtime 2 adds Multimodal in local capability data.
- Provider overlap exists on OpenAI API; start route-level A/B tests there.
- GPT-5.3-Codex is $50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Multimodal before moving production traffic.
- GPT-5.3-Codex adds Vision, Structured outputs, and Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-05 | 2026-05-07 |
| Context window | 400K | 131K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-08 | - |
Pricing and availability
| Pricing attribute | GPT-5.3-Codex | GPT Realtime 2 |
|---|---|---|
| Input price | $1.75/1M tokens | $32/1M tokens |
| Output price | $14/1M tokens | $64/1M tokens |
| Providers |
Capabilities
| Capability | GPT-5.3-Codex | GPT Realtime 2 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | No | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: GPT-5.3-Codex, multimodal input: GPT Realtime 2, structured outputs: GPT-5.3-Codex, and code execution: GPT-5.3-Codex. Both models share reasoning mode, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, GPT-5.3-Codex lists $1.75/1M input and $14/1M output tokens, while GPT Realtime 2 lists $32/1M input and $64/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GPT-5.3-Codex lower by about $36.17 per million blended tokens. Availability is 2 providers versus 1, so concentration risk also matters.
Choose GPT-5.3-Codex when coding workflow support, larger context windows, and lower input-token cost are central to the workload. Choose GPT Realtime 2 when provider fit are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, GPT-5.3-Codex or GPT Realtime 2?
GPT-5.3-Codex supports 400K tokens, while GPT Realtime 2 supports 131K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, GPT-5.3-Codex or GPT Realtime 2?
GPT-5.3-Codex is cheaper on tracked token pricing. GPT-5.3-Codex costs $1.75/1M input and $14/1M output tokens. GPT Realtime 2 costs $32/1M input and $64/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is GPT-5.3-Codex or GPT Realtime 2 open source?
GPT-5.3-Codex is listed under Proprietary. GPT Realtime 2 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GPT-5.3-Codex or GPT Realtime 2?
GPT-5.3-Codex has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-5.3-Codex or GPT Realtime 2?
GPT Realtime 2 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run GPT-5.3-Codex and GPT Realtime 2?
GPT-5.3-Codex is available on OpenRouter and OpenAI API. GPT Realtime 2 is available on OpenAI API. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Continue comparing
Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.