API cost decision in 10 seconds

GPT-5 Chat vs GPT-5.1-Codex-Mini

Pick GPT-5.1-Codex-Mini when budget and context both matter.

Page updated: 2026-05-26T15:08:08Z Data confirmed: 2026-05-26T18:08:02Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GPT-5.1-Codex-Mini when budget and context both matter.

On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $6.25 for GPT-5 Chat, saving $5 (80% lower).

Cost-first pickGPT-5.1-Codex-Mini

Context-first pickGPT-5.1-Codex-Mini

Sample savings$580%

10x traffic gap$50

GPT-5.1-Codex-Mini is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $50. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GPT-5.1-Codex-Mini stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	GPT-5 Chat	GPT-5.1-Codex-Mini
Input-heavy / RAG	5M input + 500K output	GPT-5.1-Codex-Mini	$11.25	$2.25
Balanced workload	1M input + 1M output	GPT-5.1-Codex-Mini	$11.25	$2.25
Output-heavy chatbot	1M input + 5M output	GPT-5.1-Codex-Mini	$51.25	$10.25

Cheaper input GPT-5.1-Codex-Mini $1.25 vs $0.25 / 1M

GPT-5.1-Codex-Mini is $1 cheaper per 1M input tokens (80% lower; 5x difference).

Cheaper output GPT-5.1-Codex-Mini $10 vs $2 / 1M

GPT-5.1-Codex-Mini is $8 cheaper per 1M output tokens (80% lower; 5x difference).

Larger context GPT-5.1-Codex-Mini 128K vs 400K

GPT-5.1-Codex-Mini has 272K more context (3.12x larger).

Sample workload GPT-5.1-Codex-Mini $6.25 vs $1.25

GPT-5.1-Codex-Mini is $5 cheaper on the standard workload (80% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

GPT-5 Chat Calculating… Estimated API cost

GPT-5.1-Codex-Mini Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

GPT-5.1-Codex-Mini has the lower input price; GPT-5.1-Codex-Mini has the lower output price; GPT-5.1-Codex-Mini offers the larger context window. For the 1M input plus 500K output sample, GPT-5.1-Codex-Mini is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $6.25 for GPT-5 Chat and $1.25 for GPT-5.1-Codex-Mini.

Best Fit

Choose GPT-5 Chat when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Choose GPT-5.1-Codex-Mini when you care most about lower input-token price, lower output-token price, and larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $6.25 for GPT-5 Chat, saving $5 (80% lower).
GPT-5.1-Codex-Mini is $5 cheaper on the standard workload (80% lower).
GPT-5.1-Codex-Mini is $1 cheaper per 1M input tokens (80% lower; 5x difference).
GPT-5.1-Codex-Mini is $8 cheaper per 1M output tokens (80% lower; 5x difference).
GPT-5.1-Codex-Mini has 272K more context (3.12x larger).

Head-to-Head Specs

Feature	GPT-5 Chat (OpenAI)	GPT-5.1-Codex-Mini (OpenAI)
Input Price prompt tokens per 1M	$1.25	$0.25
Completion Price per 1M tokens	$10	$2
Sample Workload Cost 1M input + 500K output	$6.25	$1.25
Context Window	128K	400K
Release Date	2025-08-07	2025-11-13
Popularity	#111	#141

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GPT-5.1-Codex-Mini	On the standard 1M input plus 500K output workload, GPT-5.1-Codex-Mini is estimated at $1.25 vs $6.25 for GPT-5 Chat, saving $5 (80% lower).
High-volume input processing	GPT-5.1-Codex-Mini	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GPT-5.1-Codex-Mini	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	GPT-5.1-Codex-Mini	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

gpt-oss-120b (free) can replace GPT-5 Chat when lower sample workload cost matters most: $0.
gpt-oss-20b (free) can replace GPT-5 Chat when lower sample workload cost matters most: $0.
gpt-oss-20b can replace GPT-5 Chat when lower sample workload cost matters most: $0.1.
gpt-oss-120b can replace GPT-5 Chat when lower sample workload cost matters most: $0.13.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.

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Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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OpenAI catalog

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GPT-5 Chat

GPT-5 Chat is designed for advanced, natural, multimodal, and context-aware conversations for enterprise applications.

GPT-5.1-Codex-Mini

GPT-5.1-Codex-Mini is a smaller and faster version of GPT-5.1-Codex