GPT-5.3 Codex vs o3-pro

Compare OpenAI and OpenAI AI models

OpenAI

GPT-5.3 Codex

OpenAI

o3-pro

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

GPT-5.3 Codex

Per Request:$0.008750

Daily:$0.875

Monthly:$26.25

Yearly:$319.375

o3-pro

Per Request:$0.06

Daily:$6.00

Monthly:$180.00

Yearly:$2,190.00

Cost Differences

+$0.05125

Per Request

+$5.125

Daily

+$153.75

Monthly

+$1,870.625

Yearly

o3-pro costs more than GPT-5.3 Codex

Feature Comparison

Feature	GPT-5.3 Codex	o3-pro
Provider	OpenAI	OpenAI
Input Price	$1.75/1M tokens	$20.00/1M tokens
Output Price	$14.00/1M tokens	$80.00/1M tokens
Context Window	256,000 tokens	1,000,000 tokens
Max Output	32,768 tokens	131,072 tokens
Category	coding	reasoning
Capabilities	textcode	textreasoningcode
Release Date	3/1/2026	6/10/2025

GPT-5.3 Codex vs o3-pro: Which Should You Choose?

Choosing between GPT-5.3 Codex and o3-pro depends on your priorities: cost efficiency, context length, or raw capability. GPT-5.3 Codex is the more affordable option at $1.75/1M input tokens — 91% cheaper than o3-pro. Meanwhile, o3-pro 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-5.3 Codex is a coding model while o3-pro is reasoning. This means they're optimized for different workloads. o3-pro targets more demanding workloads, while GPT-5.3 Codex provides a cost-effective option for everyday tasks.

Output costs matter too. GPT-5.3 Codex charges $14.00/1M output tokens vs $80.00 for o3-pro. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. GPT-5.3 Codex has the edge here at $14.00/1M output tokens.

Best Use Cases

Choose GPT-5.3 Codex when:

• Budget is a primary concern
• You're already using OpenAI's API ecosystem

Choose o3-pro when:

• You need a larger context window (1,000,000 tokens)
• You need more capabilities (reasoning)
• You need longer outputs (up to 131,072 tokens)
• 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-5.3 Codex (OpenAI)

Cost Calculator

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o3-pro (OpenAI)

Cost Calculator

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Frequently Asked Questions

Which is cheaper, GPT-5.3 Codex or o3-pro?▼

GPT-5.3 Codex is cheaper for input tokens at $1.75 per million tokens vs $20.00 for o3-pro — that's 91% savings on input costs.

What is the context window difference between GPT-5.3 Codex and o3-pro?▼

GPT-5.3 Codex supports 256,000 tokens while o3-pro supports 1,000,000 tokens — a difference of 744,000 tokens in favor of o3-pro.

Which model is better for AI Chatbot?▼

Both models support text. For ai chatbot, GPT-5.3 Codex is the lower-cost option, while o3-pro offers a larger context window (1,000,000 vs 256,000 tokens). Choose GPT-5.3 Codex for budget sensitivity or o3-pro 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-5.3 Codex costs about $26.25/month and o3-pro costs about $180.00/month. Overall, GPT-5.3 Codex has lower combined input + output rates ($1.75 in, $14.00 out) vs o3-pro.