GPT-4o vs Grok 4.5
At a Glance
| Compare |  GPT-4oOpenAI | Grok 4.5xAI |
|---|---|---|
| Intelligence, Cost, and Efficiency | ||
| IntelligenceHigher is better · MM Intelligence v2.5 | UnrankedNot in the 46-model eligible cohort | #25 of 4660.1 score · 3/3 sources · complete |
| CostLower is better · Published-token output estimate | UnrankedNot in the 44-model eligible cohort | #15 of 44$0.063 per LiveBench case |
| EfficiencyHigher is better · MM Efficiency v1.5 | UnrankedNot in the 38-model eligible cohort | #11 of 3859.2 score · 3/3 sources · complete |
| Pricing and Limits | ||
| Input priceFrom · USD / 1M tokens | $1.25Openrouter ↗ · Sep 22, 2026 | $2.00Xai ↗ · Sep 3, 2026 |
| Output priceFrom · USD / 1M tokens | $5.00Openrouter ↗ · Sep 22, 2026 | $6.00Xai ↗ · Sep 3, 2026 |
| Context windowMaximum documented tokens | 128K | 500K |
| Model facts checked | Aug 29, 2026View model evidence → | Sep 3, 2026View model evidence → |
Token prices are the lowest available sourced USD rates; input and output may use different providers. Cost ranking estimates output spend on LiveBench, not a full request bill. Ranking methodology →
Available Benchmarks
| Benchmark | GPT-4o | Grok 4.5 |
|---|---|---|
| LMArena Text Arenatext-2026-09-13-d25aabda0010 · arena_rating · leader | 1,282.4588% of row best · rating · gpt-4o-2024-08-06; 95% CI [1278.25455133, 1286.63762056]; votes 45499; rank 254 | 1,450.13100% of row best · rating · grok-4.5; 95% CI [1445.44268767, 1454.81726995]; votes 30103; rank 45 |
| LMArena Vision Arenavision-2026-09-13-d25aabda0010 · arena_rating · leader | 1,064.5683% of row best · rating · gpt-4o-2024-08-06; 95% CI [1052.10383916, 1077.00692124]; votes 3376; rank 123 | 1,288.54100% of row best · rating · grok-4.5; 95% CI [1280.47745270, 1296.60872281]; votes 8355; rank 24 |
| ToneBench2026-09-11-10-task-4ef099199c9c · overall_score · unverified | 58.6671% of row best · points · GPT-4o · 1,174 output tokens / case | 82.23100% of row best · points · Grok 4.5 · 2,688 output tokens / case |
| Overall ResultCounted from the protocol-matched rows above | 0 benchmark winsNo overall winner | 2 benchmark winsNo overall winner |
Third-party benchmark Only like-for-like primary-publisher results are shown; raw scores, relative scores, configuration, and token spend remain visible.
Side-by-Side Facts
| Field | GPT-4o | Grok 4.5 |
|---|---|---|
| Developer | OpenAI | xAI |
| Family | Gpt 4o | Grok 4 |
| Model | GPT-4o | Grok 4.5 |
| Version | GPT-4o | Grok 4.5 |
| Lifecycle | active | active |
| Released | Unknown | 2026-07-16 |
| Knowledge cutoff | 2023-10-01 | Unknown |
| Input modalities | Text, Image | Text, Image |
| Output modalities | Text | Text |
| Context window | 128K | 500K |
| Total parameters | Unknown | Unknown |
| Active parameters | Unknown | Unknown |
| License | Unknown | Unknown |
| Open weights | No | No |
| API available | Yes | Yes |
| Self-hostable | No | No |
| Provider access | Openai (Standard), Openrouter (Standard) | Xai (Standard) |
| Capabilities | chat, generation, tools | chat, generation, reasoning, structured_outputs, tools |
GPT-4o Capabilities
Grok 4.5 Capabilities
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Primary Evidence
Sources and Freshness
Questions
GPT-4o vs Grok 4.5 FAQs
Is GPT-4o or Grok 4.5 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both GPT-4o and Grok 4.5, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, GPT-4o or Grok 4.5?+
GPT-4o is $1.25 and Grok 4.5 is $2.00 per million tokens, so GPT-4o is cheaper on this metric. GPT-4o is $5.00 and Grok 4.5 is $6.00 per million tokens, so GPT-4o is cheaper on this metric.
Which has a larger context window, GPT-4o or Grok 4.5?+
Grok 4.5 has the larger sourced context window. GPT-4o supports 128K and Grok 4.5 supports 500K.
Which performs better in benchmarks, GPT-4o or Grok 4.5?+
There is no overall benchmark winner: An overall winner requires at least two decisive benchmarks from at least two original publishers.
Can GPT-4o or Grok 4.5 be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. GPT-4o is not marked open weight; Grok 4.5 is not marked open weight.
Can GPT-4o and Grok 4.5 understand images?+
GPT-4o is documented with image input; Grok 4.5 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, GPT-4o or Grok 4.5?+
Neither has a larger sourced maximum output. GPT-4o is 16K and Grok 4.5 is —.
Do GPT-4o and Grok 4.5 support reasoning and tool use?+
GPT-4o: tool calling and image input. Grok 4.5: reasoning, tool calling, and image input. Feature support does not establish relative quality.
Which is available from more inference providers, GPT-4o or Grok 4.5?+
GPT-4o has 2 sourced provider routes; Grok 4.5 has 1, so GPT-4o has broader tracked availability.
Which offers better value, GPT-4o or Grok 4.5?+
There is no universal value winner. Compare the input and output prices above with the matched benchmark result for your workload: cheaper tokens can be offset by different quality, token usage, latency, or provider availability.