GPT-5 vs Grok 4-20
Complete pricing and performance comparison between OpenAI's GPT-5 and xAI's Grok 4-20.
Quick Verdict
Cheaper
GPT-5 (input) / Grok 4-20 (output)
Input: 1.6x diff, Output: 1.7x diff
Larger Context
GPT-5
400K vs 131K
Higher Quality
Grok 4-20
Score: 49 vs 45
Faster
Grok 4-20
101 vs 63 tok/s
Pricing Comparison
| Spec | GPT-5 | Grok 4-20 | Difference |
|---|---|---|---|
| Provider | OpenAI | xAI | |
| Input / 1M tokens | $1.25 | $2 | GPT-5 is 38% more expensive |
| Output / 1M tokens | $10 | $6 | Grok 4-20 is 40% more expensive |
| Context Window | 400K | 131K | 3x difference |
| Max Output | 16K | 16K | |
| Tokenizer | o200k_base | cl100k_base |
Performance Benchmarks
| Metric | GPT-5 | Grok 4-20 | Winner |
|---|---|---|---|
| Quality Index | 45 | 49 | Grok 4-20 |
| Output Speed | 63 tok/s | 101 tok/s | Grok 4-20 |
| Time to First Token | 77.71s | 20.69s | Grok 4-20 |
| Value (Quality/$) | 35.7 | 24.3 | Higher = better value |
Benchmark data from Artificial Analysis. Quality Index is a composite score across reasoning, coding, and knowledge tasks.
Cost at Scale
Estimated cost at different usage levels (3:1 input-to-output token ratio, typical for chat).
| Usage | GPT-5 | Grok 4-20 | Savings |
|---|---|---|---|
Single request 1K in / 300 out | $0.0042 | $0.0038 | Same |
10 requests 10K in / 3K out | $0.042 | $0.038 | Grok 4-20 saves $0.0045 |
100 requests 100K in / 30K out | $0.425 | $0.380 | Grok 4-20 saves $0.045 |
1,000 requests 1M in / 300K out | $4.25 | $3.80 | Grok 4-20 saves $0.450 |
10,000 requests 10M in / 3M out | $42.50 | $38.00 | Grok 4-20 saves $4.50 |
1M requests/mo 1B in / 300M out | $4250.00 | $3800.00 | Grok 4-20 saves $450.00 |
Pros & Cons
GPT-5 Strengths
- +Cheaper input tokens
- +Larger context window (400K vs 131K)
Grok 4-20 Strengths
- +Cheaper output tokens
- +Faster output (101 vs 63 tok/s)
- +Higher quality score (49 vs 45)
- +Lower latency (faster first token)
When to Use Each Model
Choose GPT-5 for
- →Long documents, large codebases, or multi-turn conversations
Choose Grok 4-20 for
- →Tasks requiring maximum accuracy and reasoning
- →Real-time applications, chat, or autocomplete
Frequently Asked Questions
Which is cheaper, GPT-5 or Grok 4-20?
For input tokens, GPT-5 is 1.6x cheaper at $1.25/1M tokens. For output tokens, Grok 4-20 is 1.7x cheaper at $6/1M tokens. At typical usage (1M input + 300K output), GPT-5 costs $4.25 vs Grok 4-20 at $3.80.
What's the context window difference?
GPT-5 supports 400K context (400,000 tokens), while Grok 4-20 supports 131K (131,072 tokens). GPT-5 can handle 3x more context in a single request.
Which model has better benchmarks?
Quality Index: GPT-5 scores 45 vs Grok 4-20 at 49. Speed: GPT-5 generates 63 tok/s vs Grok 4-20 at 101 tok/s. Time to first token: GPT-5 at 77.71s vs Grok 4-20 at 20.69s.
When should I choose GPT-5 over Grok 4-20?
Choose GPT-5 when you need: Cheaper input tokens, Larger context window (400K vs 131K). Choose Grok 4-20 when you need: Cheaper output tokens, Faster output (101 vs 63 tok/s), Higher quality score (49 vs 45), Lower latency (faster first token).
How much would 10,000 API requests cost?
At 1K input + 300 output tokens per request (typical chat): GPT-5 = $42.50, Grok 4-20 = $38.00. At 10K input + 1K output per request (longer conversations): GPT-5 = $225.00, Grok 4-20 = $260.00.