SpaceXAI Releases Grok 4.5: Performance on Par with Opus at 1/6 the Cost, 4x Token Efficiency

On July 16, 2026, SpaceXAI (formerly xAI) officially launched its flagship model Grok 4.5. Based on a 1.5 trillion parameter MoE architecture, trained on tens of thousands of NVIDIA GB300 GPUs, and co-trained with the AI coding tool Cursor using trillions of tokens of developer interaction data, Grok 4.5 focuses on programming, agent, and knowledge work scenarios. It supports a 500K token context (upgrading to 1M next week) and achieves 80 TPS inference speed.

Performance

In multiple benchmarks, Grok 4.5 competes head-to-head with Claude Opus 4.8 and GPT-5.5, with mixed results:

• DeepSWE 1.0: 62.0%, surpassing Opus 4.8 (55.75%) and close to GPT-5.5 (64.31%)
• Terminal Bench 2.1: 83.3%, nearly tied with GPT-5.5 (83.4%) and ahead of Opus 4.8 (78.9%)
• SWE Bench Pro: 64.7%, beating GPT-5.5 (58.6%) but below Opus 4.8 (69.2%)
• SWE Marathon: 29.0%, ranked first, ahead of Opus 4.8 (26.0%)
• Harvey Legal Agent Benchmark: Ranked first

In the independent evaluation by Artificial Analysis on the GDPval-AA v2 test, Grok 4.5 scored 1543, ranking fourth globally, but the average cost per task was only $0.49, far lower than other frontier models.

Pricing and Efficiency

Grok 4.5 API pricing: $2 per million tokens for input, $6 per million tokens for output, approximately 60% cheaper than Opus 4.8. More critically, token efficiency: on SWE Bench Pro tasks, Grok 4.5 consumes an average of only about 16K tokens, while Opus 4.8 requires 67K tokens, a 4.2x efficiency improvement. Musk stated that Grok 4.5 is "roughly equivalent to Opus 4.7, but much faster."

Training and Data

Grok 4.5's training data underwent large-scale deduplication, quality filtering, and domain filtering, with reinforcement learning focusing on hundreds of thousands of real software engineering and knowledge work tasks. Co-training with Cursor is a key highlight: the model learned real interactions between developers and codebases, tools, and agents, rather than just code itself. The training system employs a highly asynchronous design, allowing the model to continue training while executing complex tasks over long periods.

Availability and Future Plans

Grok 4.5 is now available via the SpaceXAI API, the Grok Build command-line tool, and Cursor (all subscription tiers), with a limited-time free access. Musk previewed: a 1M token context version next week, and a 2 trillion parameter version by the end of the month. Additionally, Meta released Muse Spark 1.1 on the same day at lower pricing ($1.25 per million tokens input, $4.25 per million tokens output), but Grok 4.5 performs better on several benchmarks.