GPT-5.1 vs GPT-5.3 Codex

Compare OpenAI and OpenAI AI models

OpenAI

GPT-5.1

OpenAI

GPT-5.3 Codex

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Cost Comparison (1000 input + 500 output tokens, 100 requests/day)

GPT-5.1

Per Request:$0.006250

Daily:$0.625

Monthly:$18.75

Yearly:$228.125

GPT-5.3 Codex

Per Request:$0.008750

Daily:$0.875

Monthly:$26.25

Yearly:$319.375

Cost Differences

+$0.002500

Per Request

+$0.25

Daily

+$7.50

Monthly

+$91.25

Yearly

GPT-5.3 Codex costs more than GPT-5.1

Feature Comparison

Feature	GPT-5.1	GPT-5.3 Codex
Provider	OpenAI	OpenAI
Input Price	$1.25/1M tokens	$1.75/1M tokens
Output Price	$10.00/1M tokens	$14.00/1M tokens
Context Window	1,000,000 tokens	256,000 tokens
Max Output	131,072 tokens	32,768 tokens
Category	flagship	coding
Capabilities	textvisionaudiocodereasoning	textcode
Release Date	11/12/2025	3/1/2026

GPT-5.1 vs GPT-5.3 Codex: Which Should You Choose?

Choosing between GPT-5.1 and GPT-5.3 Codex depends on your priorities: cost efficiency, context length, or raw capability. GPT-5.1 is the more affordable option at $1.25/1M input tokens — 29% cheaper than GPT-5.3 Codex. Meanwhile, GPT-5.1 offers a significantly larger context window at 1,000,000 tokens vs 256,000 for GPT-5.3 Codex.

These models target different tiers: GPT-5.1 is a flagship model while GPT-5.3 Codex is coding. This means they're optimized for different workloads. GPT-5.1 is built for complex tasks that require deeper reasoning, while GPT-5.3 Codex offers better value for routine operations.

Output costs matter too. GPT-5.1 charges $10.00/1M output tokens vs $14.00 for GPT-5.3 Codex. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. GPT-5.1 has the edge here at $10.00/1M output tokens.

Multimodal capabilities: GPT-5.1 supports vision (image inputs) while GPT-5.3 Codex is text-only. If your application needs image understanding, this narrows your choice.

Best Use Cases

Choose GPT-5.1 when:

• Budget is a primary concern
• You need a larger context window (1,000,000 tokens)
• You need more capabilities (vision, audio, reasoning)
• You need longer outputs (up to 131,072 tokens)
• You're already using OpenAI's API ecosystem

Choose GPT-5.3 Codex when:

• You're already using OpenAI's API ecosystem

Try Different Scenarios

Use the calculator below to see how costs change with different usage patterns

GPT-5.1 (OpenAI)

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GPT-5.3 Codex (OpenAI)

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Frequently Asked Questions

Which is cheaper, GPT-5.1 or GPT-5.3 Codex?▼

GPT-5.1 is cheaper for input tokens at $1.25 per million tokens vs $1.75 for GPT-5.3 Codex — that's 29% savings on input costs.

What is the context window difference between GPT-5.1 and GPT-5.3 Codex?▼

GPT-5.1 supports 1,000,000 tokens while GPT-5.3 Codex supports 256,000 tokens — a difference of 744,000 tokens in favor of GPT-5.1.

Which model is better for AI Chatbot?▼

Both models support text. For ai chatbot, GPT-5.1 is the lower-cost option, while GPT-5.1 offers a larger context window (1,000,000 vs 256,000 tokens). Choose GPT-5.1 for budget sensitivity or GPT-5.1 for longer context tasks.

Which model has better overall pricing for heavy usage?▼

At 100 requests/day with 1,000 input and 500 output tokens each, GPT-5.1 costs about $18.75/month and GPT-5.3 Codex costs about $26.25/month. Overall, GPT-5.1 has lower combined input + output rates ($1.25 in, $10.00 out) vs GPT-5.3 Codex.