Is GPT-5.6 Sol or Grok 4.3 cheaper?

Grok 4.3 is cheaper on all three of the workload shapes tested. On a RAG workload of 12k input and 700 output tokens at 50,000 requests per month with 60% caching, GPT-5.6 Sol costs $2,430 per month and Grok 4.3 costs $459.50. Headline rates are $5/$30 versus $1.25/$2.5 per million input/output tokens.

GPT-5.6 Sol vs Grok 4.3

Grok 4.3 is the cheaper of the two across every workload shape tested below. Headline rates are $5 in / $30 out for GPT-5.6 Sol versus $1.25 in / $2.5 out for Grok 4.3, per million tokens.

Real monthly cost, three workloads

Workload	GPT-5.6 Sol	Grok 4.3	Cheaper
Support chatbot 1.5k in / 400 out · 100k req/mo · 30% cached	$1,748	$240.25	Grok 4.3 (7.3× cheaper)
RAG / doc Q&A 12k in / 700 out · 50k req/mo · 60% cached	$2,430	$459.50	Grok 4.3 (5.3× cheaper)
Coding agent 25k in / 2.5k out · 20k req/mo · 80% cached	$2,200	$330.00	Grok 4.3 (6.7× cheaper)

Costs include prompt caching at the stated hit rate and per-model tokenizer correction. Adjust for your own traffic →

Specifications side by side

	GPT-5.6 Sol	Grok 4.3
Provider	OpenAI	xAI
Input / M tokens	$5	$1.25
Output / M tokens	$30	$2.5
Cached input	$0.5	$0.2
Context window	1050K	1000K
Batch discount	−50%	—
Tokenizer factor	×1	×1
Min prefix to cache	—	—
Announced retirement	—	—

Which should you pick?

On cost alone, Grok 4.3 wins every workload shape above.

Full detail: GPT-5.6 Sol · Grok 4.3

All figures verified 2026-08-18 against official provider documentation. Fields a provider does not publish are shown as “—” rather than estimated.