Model comparison

GPT-5.3-Codex vs Grok 4.6

Q: Is GPT-5.3-Codex or Grok 4.6 cheaper for input?

GPT-5.3-Codex is cheaper at $1.75 per million input tokens, against $2 for Grok 4.6 — roughly 1.1× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.3-Codex has tiered pricing: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. Grok 4.6 has tiered pricing: $2/$6 per MTok (<200K prompt); $4/$12 (≥200K). Cached input $0.50/MTok. Knowledge cutoff Feb 1 2026.

Q: Is GPT-5.3-Codex or Grok 4.6 cheaper for output?

Grok 4.6 is cheaper at $6 per million output tokens, against $14 for GPT-5.3-Codex — roughly 2.3× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.3-Codex has tiered pricing: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. Grok 4.6 has tiered pricing: $2/$6 per MTok (<200K prompt); $4/$12 (≥200K). Cached input $0.50/MTok. Knowledge cutoff Feb 1 2026.

Q: Which has the larger context window, GPT-5.3-Codex or Grok 4.6?

Grok 4.6 accepts 500K tokens against 400K for GPT-5.3-Codex. This only matters if you routinely send very long documents or large codebases.

Q: Do GPT-5.3-Codex and Grok 4.6 support the same reasoning levels?

GPT-5.3-Codex exposes none, low, medium, high, xhigh, max, while Grok 4.6 exposes low, medium, high, xhigh.

Q: Should I use GPT-5.3-Codex or Grok 4.6?

Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. GPT-5.3-Codex suits autonomous coding; Grok 4.6 suits coding agents.

OpenAI against xAI, compared on context, price, and verified benchmark results.

Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below

OpenAI

GPT-5.3-Codex

Frontier

xAI

Grok 4.6

Frontier

AI model capability comparison
Specification	GPT-5.3-Codex	Grok 4.6
Provider	OpenAI	xAI
Tier	Frontier	Frontier
Context window	400K	Winner: 500K
Max output	128K	Winner: 131K
Input / 1M tokens	Winner: $1.75	$2
Output / 1M tokens	$14	Winner: $6
Weights	Closed	Closed
Parameters	Not disclosedUnverified	Not disclosedUnverified
Reasoning levels	none, low, medium, high, xhigh, max	low, medium, high, xhigh
Modalities	text, image	text, image
API model id	gpt-5.3-codex	grok-4.6
Released	February 5, 2026	August 12, 2026
Artificial Analysis Intelligence Index [high] (2026-08-14)	52	Winner: 61
Terminal-Bench 2.1 (2026-08-18)	Not verifiedUnverified	88
GPQA Diamond (2026-08-18)	Not verifiedUnverified	94.9

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

2026-08-18: Artificial Analysis measurement (independent; tied 1st with Gemini 3.7 Flash high)Agentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).

Pricing tiers: GPT-5.3-Codex: Standard $1.75/$14 per MTok; cached input $0.175/MTok; Fast mode $3.50/$28. Purpose-built for the Codex agent. · Grok 4.6: $2/$6 per MTok (<200K prompt); $4/$12 (≥200K). Cached input $0.50/MTok. Knowledge cutoff Feb 1 2026.

FrontierRecord checked September 3, 2026

GPT-5.3-Codex

GPT-5.3-Codex is OpenAI's coding-specialised model powering the Codex agent at $1.75/$14.

Best for

Autonomous coding
Repo-scale refactors
Test generation

Watch out

Tuned for coding, not general chat; use GPT-5.6 for broad reasoning.

FrontierRecord checked September 3, 2026

Grok 4.6

Grok 4.6 is xAI's current flagship coding model, strong on LMArena WebDev.

Best for

Coding agents
Chat and knowledge
Cost-sensitive frontier work

Watch out

Token rates double above a 200K-token prompt.

When the cheaper one wins

Grok 4.6 is cheaper on output at $6 per million tokens against $14 for GPT-5.3-Codex — about 2.3×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

Run the model picker

Evidence confidence: High

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

Pricing verified on both sides — Input and output rates are verified for both models.
4/5 core specs verified on both sides — Not published for at least one side: parameter count.
1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
Verified within the last 90 days — Newest catalog check was 8 days ago.
Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

GPT-5.3-Codex: OpenAI — Introducing GPT-5.3-Codex (accessed 2026-08-29)
GPT-5.3-Codex: OpenAI API pricing (gpt-5.3-codex $1.75/$14) (accessed 2026-08-29)
Grok 4.6: xAI — Grok 4.6 (accessed 2026-08-29)
Grok 4.6: xAI pricing (grok-4.6 $2/$6, 500K) (accessed 2026-08-29)

Related comparisons

Diving deeper on one model? GPT-5.3-Codex · Grok 4.6

Common questions