Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | GLM-5.3-Flash | Grok 3 mini Reasoning (high) |
|---|---|---|
| Input ($/M tokens) | $0.15 | $0.3 |
| Output ($/M tokens) | $0.5 | $0.5 |
Verdict. GLM-5.3-Flash wins the overall benchmark matchup 2–0 across 2 overlapping categories, but raw benchmark score is only one input to the decision.
Pricing. Both models sit in the budget bracket for output-token pricing. At 1.0× the per-million-token cost, Grok 3 mini Reasoning (high) is meaningfully cheaper if your traffic is output-heavy (long completions, document generation, agent loops). Grok 3 mini Reasoning (high) makes more sense when output volume is low and absolute reasoning quality justifies the premium.
Strengths. GLM-5.3-Flash is strongest on Coding Index (71.5), Intelligence Index (57.5). Grok 3 mini Reasoning (high) leads on Intelligence Index (22.9).
Speed. On throughput, Grok 3 mini Reasoning (high) generates tokens at 78 tok/s versus 47 tok/s — about 39% faster. On time-to-first-token, Grok 3 mini Reasoning (high) responds in 680ms vs 1670ms, which matters most for chat-style UIs.
Provider. Z AI and SpaceXAI sell to overlapping but distinct developer audiences: Z AI tends to ship frontier reasoning models with premium positioning, while SpaceXAI often prices more aggressively. Your existing vendor relationships, billing, and SLA preferences may matter as much as the raw numbers above.
Workload cost. Workload scenarios (per million requests at 30M input + 15M output tokens): GLM-5.3-Flash costs $12.00 ($144/year); Grok 3 mini Reasoning (high) costs $16.50 ($198/year). At a smaller 5M-input/2M-output scale (single-developer tool or prototype): GLM-5.3-Flash ≈ $1.75/run, Grok 3 mini Reasoning (high) ≈ $2.50/run. At agent/realtime scale (200M input / 100M output per million requests): GLM-5.3-Flash ≈ $80/run, Grok 3 mini Reasoning (high) ≈ $110/run. GLM-5.3-Flash becomes more attractive at higher volume — the absolute per-token pricing difference compounds when you ship at scale.
Recommendation. Both models have legitimate use cases — the right answer depends on whether you are optimizing for benchmark ceiling, latency, or unit cost. Start with the cheaper / faster model, evaluate against your specific task, and only switch if the upgrade shows a meaningful lift.
Head-to-head deltas
Data from Artificial Analysis API — 12 benchmarks
GLM-5.3-Flash is cheaper overall. Its blended price (3:1 input/output ratio) is $0.24/M tokens vs $0.35/M for Grok 3 mini Reasoning (high).
GLM-5.3-Flash wins 2 out of 12 benchmarks compared to 0 for Grok 3 mini Reasoning (high). See the detailed benchmark chart above for per-category results.
Grok 3 mini Reasoning (high) generates tokens faster at 78 tok/s vs 47 tok/s. However, Grok 3 mini Reasoning (high) has lower time-to-first-token (0.68s vs 1.67s).
Choose based on your priorities: GLM-5.3-Flash for lower cost, GLM-5.3-Flash for stronger benchmark performance, and Grok 3 mini Reasoning (high) for faster generation. For latency-sensitive apps, check the TTFT comparison above.