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GPT-5.5 Pro vs Grok 4.5

GPT-5.5 Pro

OpenAI

92#6
vs
Grok 4.5

xAI

88#25
Signal-by-Signal Comparison
SignalGPT-5.5 ProDeltaGrok 4.5
Capabilities
100
--
100
Benchmarks
92
+16
76
Pricing
5
-89
94
Context window size
86
+5
81
Recency
100
--
100
Output Capacity
85
+65
20
Overall Result
3 wins
of 6
1 wins
GPT-5.5 Pro wins 3 of 6 signals

Score History

Score History (12 data points)
GPT-5.5 ProGrok 4.5
GPT-5.5 Pro

92.2

current score

Leader

GPT-5.5 Pro

right now

Grok 4.5

88.3

current score

LMMarketCap.com
Interactive Price Comparison
100Kcalls/month
1,000tokens (~1,333 chars)
500tokens (~667 chars)

GPT-5.5 Pro

OpenAI

Per request$0.120000
Daily$400.00
Monthly$12000.00
Annual$144000.00

Grok 4.5

xAI

Best Value
Per request$0.005000
Daily$16.67
Monthly$500.00
Annual$6000.00

Grok 4.5 saves you $11500.00/month

That's $138000.00/year compared to GPT-5.5 Pro at your current usage level of 100K calls/month.

96% cheaper
Choose Grok 4.5 for cost optimization

GPT-5.5 Pro pricing:
Input:$30.00/M tokens
Output:$180.00/M tokens
Grok 4.5 pricing:
Input:$2.00/M tokens
Output:$6.00/M tokens
Winner
GPT-5.5 Pro

OpenAI

92

Composite Score

Grok 4.5

xAI

88

Composite Score

Signal-by-Signal Comparison
MetricGPT-5.5 ProGrok 4.5Winner
Overall Score
92
88
GPT-5.5 Pro
Rank#6#25
GPT-5.5 Pro
Quality Rank#6#25
GPT-5.5 Pro
Adoption Rank#6#25
GPT-5.5 Pro
Parameters------
Context Window1050K500K
GPT-5.5 Pro
Pricing$30.00/$180.00/M$2.00/$6.00/M--
Signal Scores
Capabilities
100
100
GPT-5.5 Pro
Benchmarks
92
76
GPT-5.5 Pro
Pricing
5
94
Grok 4.5
Context window size
86
81
GPT-5.5 Pro
Recency
100
100
GPT-5.5 Pro
Output Capacity
85
20
GPT-5.5 Pro
Benchmark Head-to-Head(4 benchmarks)
GPT-5.5 Pro: 0Grok 4.5: 0
GPT-5.5 Pro
Grok 4.5
Normalized 0-100%
MMLU
92.4%-
GPQA Diamond
93.6%-
SWE-bench Verified
88.7%-
Arena Elo
-1469
Benchmark Interpretation

Our score (0-100) is driven by benchmark performance (90%) from Arena Elo ratings, MMLU, GPQA, HumanEval, SWE-bench, and 15+ standardized evaluations. Capabilities and context window serve as tiebreakers (10%). Learn more about our methodology.

GPT-5.5 ProElite Tier

Scores 92/100 (rank #6), placing it in the top 98% of all 290 models tracked.

Raw Quality0/100
Cost Efficiency0/100
Speed0/100
Grok 4.5Elite Tier

Scores 88/100 (rank #25), placing it in the top 92% of all 290 models tracked.

Raw Quality0/100
Cost Efficiency0/100
Speed0/100

With only a 4-point gap, these models are in the same performance tier. The practical difference in output quality is minimal - your choice should depend on pricing, latency requirements, and specific feature needs.

When to Use Each Model

Choose GPT-5.5 Pro when you need:

  • Processing long documents or large codebases (1050K token context)
  • Step-by-step reasoning and chain-of-thought problem solving

Choose Grok 4.5 when you need:

  • High-volume production workloads where API costs must be minimized
  • Step-by-step reasoning and chain-of-thought problem solving
Cost-Performance Analysis
GPT-5.5 Pro
Input cost$30.00/M tokens
Output cost$180.00/M tokens
Cost per quality point$2.278
Est. monthly (1M tokens/day)$3150.00
Grok 4.5Best Value
Input cost$2.00/M tokens
Output cost$6.00/M tokens
Cost per quality point$0.091
Est. monthly (1M tokens/day)$120.00

Grok 4.5 offers 96% better value per quality point. At 1M tokens/day, you'd spend $120.00/month with Grok 4.5 vs $3150.00/month with GPT-5.5 Pro - a $3030.00 monthly difference.

Latency & Speed
GPT-5.5 ProFaster
Speed score0/100
Grok 4.5
Speed score0/100

Both models have comparable response speeds. For most applications, the latency difference is negligible.

When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.

Example Use Cases

Code generation & review

Based on overall model capabilities and architecture for coding tasks like generating functions, debugging, and refactoring

GPT-5.5 Pro

Customer support chatbot

Suitable for user-facing chat with competitive response times. Grok 4.5 also offers lower per-token costs for high-volume support

GPT-5.5 Pro

Long document analysis

Larger context window (1050K tokens) can process longer documents, contracts, and research papers in a single pass

GPT-5.5 Pro

Batch data extraction

Lower output pricing ($6.00/M) reduces costs when processing thousands of records daily

Grok 4.5

Creative writing & content

Higher overall composite score (92/100) correlates with better nuance, coherence, and style in long-form content

GPT-5.5 Pro

Image understanding & OCR

Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly

GPT-5.5 Pro
Which Should You Choose?
Our recommendation:
GPT-5.5 Pro

GPT-5.5 Pro has a moderate advantage with a 3.9000000000000057-point lead in composite score. It wins on more signal dimensions, but Grok 4.5 has specific strengths that could make it the better choice for certain workflows.

GPT-5.5 Pro
Recommended

by OpenAI

  • Choose for Quality - Marginally better benchmark scores; both are excellent
  • Choose for Reliability - Higher uptime and faster response speeds
  • Choose for Prototyping - Stronger community support and better developer experience
  • Choose for Production - Wider enterprise adoption and proven at scale

by xAI

  • Choose for Cost - 96% lower pricing; better value at scale
Capability Comparison
CapabilityGPT-5.5 ProGrok 4.5
Vision (Image Input)
Function Calling
Streaming
JSON Mode
Reasoning
Web Search
Image Output
Monthly Cost Calculator
1,000tokens (600 in / 400 out)
100requests/day (3,000/month)

GPT-5.5 Pro

OpenAI

$270.00
estimated monthly cost

Grok 4.5

xAI

Best Value
$10.80
estimated monthly cost

Grok 4.5 saves you $259.20/month

That's 96% cheaper than GPT-5.5 Pro at 1,000 tokens/request and 100 requests/day.

Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.

Parameters & Context
ParameterGPT-5.5 ProGrok 4.5
Context Window1.1M500K
Max Output Tokens128,000--
Open SourceNoNo
CreatedApr 24, 2026Jul 8, 2026
Last updated: 17m ago

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GPT-5.5 Pro vs Grok 4.5 (2026) | LM Market Cap