text model comparison
GLM-5.3-Flash vs Grok 4.20
GLM-5.3-Flash and Grok 4.20 are both current text models, from Z.ai and xAI. GLM-5.3-Flash is 88% cheaper per 1M input tokens than Grok 4.20, $0.15 vs $1.25. On Arena Text, GLM-5.3-Flash scores 1475 Elo and Grok 4.20 1472 Elo (Arena, measured October 8, 2026). Both accept 1,000,000 tokens of context.
Data verified October 13, 2026 · Dataset 2026-10-13
Side by side
Standard-tier prices in effect today. The better value in each row is highlighted.
| Fact | GLM-5.3-Flash | Grok 4.20 |
|---|---|---|
| Price per 1M input tokens | $0.15 (better) | $1.25 |
| Price per 1M output tokens | $0.50 (better) | $2.50 |
| Cost of 10M input and 2M output tokens | $2.50 (better) | $17.50 |
| Arena Text | 1475 Elo (#21 of 49) (better) | 1472 Elo (#26 of 49) |
| GPQA Diamond | 90.2% (#27 of 40) (better) | 89.3% (#31 of 40) |
| FrontierMath Tiers 1-3 (v2) | 55.8% (#31 of 40) (better) | 44.9% (#34 of 40) |
| SimpleQA Verified | Not measured | 30.2% (#32 of 36) |
| Provider | Z.ai | xAI |
| Release date | August 26, 2026 | March 10, 2026 |
| Access | API and open weights | API only |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | Not reported |
| Input | text, image, video | text, image |
| Output | text | text |
When to choose each
GLM-5.3-Flash
Best for
- Low-cost coding from screenshots or screen recordings
- Document and research agents on a budget
Watch out for
- Thinking cannot be disabled
- A faster GLM-5.3-FlashX is a separate model id at $0.37 input and $1.25 output per 1M tokens
Grok 4.20
Best for
- Comparing single-agent and multi-agent reasoning on long-context workloads
Watch out for
- The published base rates double when requests reach the provider's 200,000-token long-context threshold
GLM-5.3-Flash vs Grok 4.20 FAQ
Which is cheaper, GLM-5.3-Flash or Grok 4.20?
GLM-5.3-Flash is 88% cheaper per 1M input tokens than Grok 4.20, $0.15 vs $1.25. For 10M input and 2M output tokens, GLM-5.3-Flash costs $2.50 and Grok 4.20 $17.50 at standard rates.
Which scores higher on independent benchmarks, GLM-5.3-Flash or Grok 4.20?
GLM-5.3-Flash leads on Arena Text, 1475 Elo to 1472 Elo; GLM-5.3-Flash leads on GPQA Diamond, 90.2% to 89.3%; GLM-5.3-Flash leads on FrontierMath Tiers 1-3 (v2), 55.8% to 44.9%. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, GLM-5.3-Flash or Grok 4.20?
Both accept 1,000,000 tokens of context.
Can I run GLM-5.3-Flash or Grok 4.20 myself?
GLM-5.3-Flash is released as open weights you can run yourself; Grok 4.20 is available through its provider's API only.
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Production evaluation
Choosing between GLM-5.3-Flash and Grok 4.20?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty