GPT-5.6 Sol vs Grok 4.3: pricing and benchmarks
Grok 4.3 is 69% cheaper on input tokens ($1.25 vs $4.00 per 1M). Grok 4.3 is 88% cheaper on output tokens ($2.50 vs $20.00 per 1M). On our document Q&A workload (50,000 questions a month), Grok 4.3 costs $575.00 a month versus $2,200 for GPT-5.6 Sol, 74% less. Epoch AI has not published a capability index score for Grok 4.3 yet.
Prices verified September 14, 2026.
Which should you choose?
Epoch AI has not published a capability index score for Grok 4.3 yet.
Grok 4.3 costs $1.563 per 1M tokens (3:1 input-to-output mix) vs $8.00 for GPT-5.6 Sol, 80% less.
Pricing and specs
| GPT-5.6 Sol | Grok 4.3 | |
|---|---|---|
| Provider | OpenAI | xAI |
| API model ID | gpt-5.6-sol | grok-4.3 |
| Input / 1M tokens | $4.00 | $1.25 |
| Cached input / 1M tokens | $0.40 | $0.20 |
| Output / 1M tokens | $20.00 | $2.50 |
| Long-context rates | $8.00 in / $30.00 out on long-context requests | $2.50 in / $5.00 out above 200K prompt tokens |
| Context window | 1.05M tokens | 1M tokens |
| Max output | 128K tokens | — |
| Batch discount | 50% off | — |
Benchmarks
| GPT-5.6 Sol | Grok 4.3 | |
|---|---|---|
| Epoch Capabilities Index | 161.8 | — |
| GPQA Diamond· Science reasoning | 91.3% | — |
| FrontierMath (Tiers 1–3)· Advanced math | 89.1% | — |
| SimpleQA Verified· Factual accuracy | 69.7% | — |
| ARC-AGI-2· Abstract reasoning | 92.5% | — |
| DeepSWE· Coding | 72.7% | — |
| APEX-Agents· Agentic work | 40.0% | — |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | GPT-5.6 Sol | Grok 4.3 | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $1,400 | $287.50 | Grok 4.3 79% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $2,200 | $575.00 | Grok 4.3 74% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $992.00 | $256.00 | Grok 4.3 74% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
GPT-5.6 Sol vs Grok 4.3 cost calculator
- $575.00/mo$0.01 / request
- GPT-5.6 SolOpenAI$2,200/mo$0.04 / request
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
GPT-5.6 Sol pricing notes
OpenAI’s flagship GPT-5.6 model for complex professional work.
- Promotional pricing, available at least through November 21, 2026.
- Cache writes are billed at $5 per 1M tokens.
- Regional (data residency) endpoints add a 10% uplift.
Grok 4.3 pricing notes
An earlier Grok 4 model with a 1M-token context window.
- Requests with 200K or more prompt tokens are billed at $2.50 input / $0.40 cached / $5 output for all tokens.
Frequently asked questions
- Is GPT-5.6 Sol cheaper than Grok 4.3?
- Grok 4.3 is 69% cheaper on input tokens ($1.25 vs $4.00 per 1M). Grok 4.3 is 88% cheaper on output tokens ($2.50 vs $20.00 per 1M). On our document Q&A workload (50,000 questions a month), Grok 4.3 costs $575.00 a month versus $2,200 for GPT-5.6 Sol, 74% less.
- Which is more capable, GPT-5.6 Sol or Grok 4.3?
- Epoch AI has not published a capability index score for Grok 4.3 yet.
- How much does GPT-5.6 Sol cost per 1M tokens?
- GPT-5.6 Sol costs $4.00 per 1M input tokens and $20.00 per 1M output tokens, and $0.40 per 1M cached input tokens on OpenAI’s standard tier.
- How much does Grok 4.3 cost per 1M tokens?
- Grok 4.3 costs $1.25 per 1M input tokens and $2.50 per 1M output tokens, and $0.20 per 1M cached input tokens on xAI’s standard tier.
- Which has the larger context window, GPT-5.6 Sol or Grok 4.3?
- GPT-5.6 Sol has the larger context window: 1.05M tokens versus 1M for Grok 4.3.