GPT 5.5 vs Grok 4 1 Fast Non Reasoning pricing
Side-by-side token pricing for GPT 5.5 (OpenAI) and Grok 4 1 Fast Non Reasoning (xAI), plus the total cost at three workload sizes so the crossover point is obvious. Prices refreshed 2026-09-18 00:09 UTC.
| Metric | GPT 5.5 | Grok 4 1 Fast Non Reasoning |
|---|---|---|
| Input $/1M tokens | $5 | $1.25 |
| Output $/1M tokens | $30 | $2.5 |
| Cached input $/1M | $0.5 | $0.2 |
| Context window | 1.1M | 2M |
| Max output | 128K | 2M |
| Vision | yes | yes |
| Tool calling | yes | yes |
| Cache pricing | yes | yes |
Total cost by workload
| Workload | GPT 5.5 | Grok 4 1 Fast Non Reasoning | Cheaper |
|---|---|---|---|
| 1M tokens in · 300K out | $14 | $2 | Grok 4 1 Fast Non Reasoning (86% less) |
| 10M tokens in · 3M out | $140 | $20 | Grok 4 1 Fast Non Reasoning (86% less) |
| 100M tokens in · 30M out | $1400 | $200 | Grok 4 1 Fast Non Reasoning (86% less) |
On blended cost (weighted 3:1 toward input), Grok 4 1 Fast Non Reasoning comes out cheaper by roughly 75% on input pricing. Pick Grok 4 1 Fast Non Reasoning when the workload is price-sensitive and its context window covers your prompts; GPT 5.5 is the one to benchmark if you need vision, reasoning depth, or a different quality profile.
Frequently asked
› Is GPT 5.5 cheaper than Grok 4 1 Fast Non Reasoning?
On input pricing, Grok 4 1 Fast Non Reasoning is cheaper ($1.25 vs $5 per 1M tokens). On blended cost the winner is Grok 4 1 Fast Non Reasoning, because output tokens are weighted differently for most workloads.
› Which has the larger context window?
Grok 4 1 Fast Non Reasoning offers the larger context (2M tokens).
› Do these prices include prompt caching?
Cached input is priced separately where a provider publishes a cache rate; the table above lists it per model so the comparison stays like-for-like.