Last verified 2026-03-06 (left) · 2025-11-26 (right)

GPT-5.1 vs Grok 4.1 — Pricing & Capability Comparison

GPT-5.1 charges $1.25 per million input tokens and $10.00 per million output tokens. Grok 4.1 comes in at $0.20 / $0.50. Context windows span 200K vs 2M tokens respectively.

TL;DR — Quick Comparison

✓Grok 4.1 is cheaper overall: $0.70 per 1M tokens (in+out) vs $11.25 for GPT-5.1 — saves $10.55 per 1M tokens
✓Input pricing: GPT-5.1 $1.25/1M vs Grok 4.1 $0.20/1M
✓Output pricing: GPT-5.1 $10.00/1M vs Grok 4.1 $0.50/1M
✓Context window: Grok 4.1 offers more (2M vs 200K)
✓Use our calculator below to estimate costs for your specific usage pattern

Input price (per 1M)

GPT-5.1

$1.25

Grok 4.1

$0.20

Grok 4.1 leads here

Output price (per 1M)

GPT-5.1

$10.00

Grok 4.1

$0.50

Grok 4.1 leads here

Context window

GPT-5.1

200,000 tokens

Grok 4.1

2,000,000 tokens

Grok 4.1 leads here

Cached input

GPT-5.1

$0.125

Grok 4.1

$0.050

Grok 4.1 leads here

Which one should you choose?

Skip the spreadsheet if you just need the practical takeaway. Use these rules when deciding between GPT-5.1 and Grok 4.1.

Choose Grok 4.1 if input tokens dominate your bill

Grok 4.1 has the lower input rate, which usually matters most for chat, RAG, classification, and long-prompt workflows where prompt volume stays much larger than generated output.

Choose Grok 4.1 if you generate long answers

Grok 4.1 is cheaper on output tokens, so it tends to win for report generation, coding assistance, reasoning traces, and any workflow where completions are long.

Choose Grok 4.1 if context size is the blocker

Grok 4.1 offers the larger published context window, which is more important than small pricing differences when you need to fit large files, long chats, or multi-document prompts into one request.

Cost comparison for 10K-token workloads

Side-by-side pricing for identical workloads (10,000 total tokens per request) across different distributions.

Scenario	GPT-5.1	Grok 4.1	GPT-5.1 cached	Grok 4.1 cached
Balanced conversation 50% input · 50% output	$0.0563	$0.0035	$0.0506	$0.0027
Input-heavy workflow 80% input · 20% output	$0.0300	$0.0026	$0.0210	$0.0014
Generation heavy 30% input · 70% output	$0.0738	$0.0041	$0.0704	$0.0037
Cached system prompt 90% cached input · 10% fresh output	$0.0212	$0.0023	$0.0111	$0.0009

Frequently asked questions

Which is cheaper: GPT-5.1 or Grok 4.1?

Grok 4.1 is cheaper for input tokens at $0.20 per 1M tokens compared to $1.25. For output, Grok 4.1 costs $0.50 per 1M tokens versus $10.00 for GPT-5.1.

What is the cost per 1M tokens for GPT-5.1?

GPT-5.1 pricing: $1.25 per 1M input tokens and $10.00 per 1M output tokens. Context window: 200,000 tokens.

What is the cost per 1M tokens for Grok 4.1?

Grok 4.1 pricing: $0.20 per 1M input tokens and $0.50 per 1M output tokens. Context window: 2,000,000 tokens.

How much does it cost per 1K tokens?

Per 1K tokens: GPT-5.1 costs $0.0013 input / $0.0100 output. Grok 4.1 costs $0.0002 input / $0.0005 output. This is useful for calculating small-scale usage costs.

Which model supports a larger context window?

Grok 4.1 offers 2,000,000 tokens (2M) versus 200K for GPT-5.1.

What is the estimated monthly cost for typical usage?

For a typical workload of 10M input + 2M output tokens per month: GPT-5.1 would cost approximately $32.50, while Grok 4.1 would cost $3.00. Grok 4.1 is more economical for this usage pattern.

Do these models support prompt caching?

GPT-5.1 supports prompt caching at $0.125 per 1M cached tokens, reducing costs for repeated context by up to 90%. Grok 4.1 supports caching at $0.050 per 1M tokens, saving up to 75%.

Which model is best for my use case?

Choose Grok 4.1 for cost-sensitive applications with high input volume. Choose Grok 4.1 if you need 2M context for long documents or conversations. Consider prompt caching if you have repeated context. Use our token calculator to model your specific usage pattern.