GPT-5.6 Terra vs Grok 4.3

Both are Mid-tier models, from OpenAI and xAI respectively. Grok 4.3 is the cheaper choice overall at a 4:1 input:output ratio.

Which is cheaper

Input price: Grok 4.3 is cheaper ($1.25 vs $2.00).
Output price: Grok 4.3 is cheaper ($2.50 vs $12.00).
Blended, 4:1 input:output ratio: Grok 4.3 is 62.5% cheaper ($1.50 vs $4.00 per weighted 1M tokens).

Side by side

Spec	GPT-5.6 Terra	Grok 4.3
Provider	OpenAI	xAI
Tier	Mid	Mid
Context window	1.05M	1M
Max output	128K	—
Input $/1M	$2.00	$1.25
Output $/1M	$12.00	$2.50
Cache read $/1M	$0.20	$0.20
Cache write $/1M	$2.50	—
Modalities	text, image	text, image

GPT-5.6 Terra. One flat rate: unlike Sol and Cyber, Terra has no long-context surcharge tier on the pricing page.

Grok 4.3. Short-context rate, for prompts under 200K tokens. At 200K and above: $2.50 input / $5 output, cache read $0.40 per 1M. Eligible for a 20% Batch API discount.

Sources

GPT-5.6 Terra — verified August 29, 2026

Grok 4.3 — verified August 29, 2026

Full GPT-5.6 Terra pricing page → · Full Grok 4.3 pricing page →