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gpt-oss-120b vs Grok 4.5

Compare gpt-oss-120b from OpenAI and Grok 4.5 from Grok on key metrics including benchmarks, price, context length, and other model features. Access both models and hundreds of others through the AIHubMix API.

OpenAIgpt-oss-120bGrokGrok 4.5
+ Add model · 2/4
OpenAI logo
gpt-oss-120b
OpenAI · text → text

gpt-oss-120b is a 117B-parameter open-weight Mixture-of-Experts (MoE) language model from OpenAI, designed for high-reasoning, agentic, and general-purpose production use cases. Activating just 5.1B parameters per pass, it is optimized to run on a single H100 GPU with native MXFP4 quantization. The model features configurable reasoning depth, full chain-of-thought access, and native tool use, including function calling, browsing, and structured output generation.

Input$0.18 /M
Output$0.90 /M
Details
Grok logo
Grok 4.5
Grok · text, image → text

Grok 4.5 was trained on datasets spanning knowledge in coding, science, engineering, and math. With both intelligent and efficient reasoning, Grok 4.5 excels at real engineering tasks and exceeds comparable leading models at these tasks.

Input$2.00 /M
Output$6.00 /M
Details

Pricing & Specifications

Prices are per million tokens. Time to First Token and throughput are rolling averages measured on AIHubMix.

gpt-oss-120b
Grok 4.5
Input /M
$0.18
$2.00
Output /M
$0.90
$6.00
Cache read /M
$0.18
$0.50
Context length
131,072
500,000
Max output
32,768
500,000
Time to First Token
0.2 s
2.8 s
Throughput
1101.0 tok/s
32.4 tok/s
Modalities
text
textimage
Supported Parameters
thinkingfunction callingstructured outputs
thinkingtoolsfunction callingstructured outputslong context
API Formats
Released
-
July 2026

Promotional prices show the discounted rate; see each model page for promotion windows.

Activity Past 30 Days

Daily traffic served through AIHubMix — how demand for each model is trending.

gpt-oss-120bgrok-4.5

Tokens / day

-

Requests / day

-

Performance Past 3 Days

Measured on real AIHubMix traffic, hourly buckets. Gaps mean no traffic in that hour.

gpt-oss-120bgrok-4.5

Throughput (tok/s)

-

TTFT (s)

-

Uptime (%)

-

LMArena Benchmarks

LMArena ratings by capability (Bradley-Terry, commonly called Elo). Higher is better.

Text
gpt-oss-120bgrok-4.5
1260134014201500
Overall
13521470
Coding
13901523
Math
13811478
Hard prompts
13621495
Instruction following
13251466
Multi-turn
13271477
Creative writing
12771449
Longer query
13251485
Chinese
13721511
English
13601475

Source: LMArena (arena.ai) leaderboard, imported by AIHubMix. Models without published ratings are omitted per chart.

Cost calculator

Estimate your monthly bill for the same workload on each model.

gpt-oss-120b
$24.30 /mo
Grok 4.5
$210 /mo

Monthly = daily × 30. Discounted rates applied where a promotion is active.

FAQ

Which is cheaper: gpt-oss-120b, Grok 4.5?

gpt-oss-120b: $0.90/M output tokens; Grok 4.5: $6.00/M. Use the cost calculator above to estimate your own workload.

How do their coding arena scores compare?

Grok 4.5: 1523; gpt-oss-120b: 1390 (LMArena coding leaderboard).

Which responds faster?

gpt-oss-120b: 0.2s time to first token measured on AIHubMix; see the live performance charts above for how each model behaves across the day.

How large is each context window?

gpt-oss-120b accepts 131,072 and Grok 4.5 accepts 500,000 input tokens. Maximum output per request is 32,768 tokens on gpt-oss-120b and 500,000 tokens on Grok 4.5.

Which one generates tokens faster?

gpt-oss-120b at 1101.0 tok/s and Grok 4.5 at 32.4 tok/s, measured as output throughput on AIHubMix — a separate metric from time to first token.

What inputs and capabilities does each model support?

gpt-oss-120b accepts text input and supports thinking, function calling and structured outputs; Grok 4.5 accepts text and image input and supports thinking, tool calling, function calling, structured outputs and long context.

Can I call gpt-oss-120b and Grok 4.5 with the same API key?

Yes. AIHubMix serves every model on this page behind one OpenAI-compatible endpoint, so switching between them is a one-line change to the model field — no second account, key or SDK.

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