---
title: "SpaceXAI: Grok 4.20 — price, capability and what beats it · Undominated.ai"
canonical: https://undominated.ai/models/x-ai__grok-4.20/
description: "SpaceXAI: Grok 4.20: $1.25/M in, $2.50/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper."
---

# SpaceXAI: Grok 4.20 — price, capability and what beats it · Undominated.ai

> SpaceXAI: Grok 4.20: $1.25/M in, $2.50/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper.

[Leaderboard](/) / xAI

# Grok 4.20

xAI · released 2026-03-31 · proprietary

 $1.56 per million tokens, balanced Balanced Summarise Chat Code gen Agentic

## No independent quality score.

No benchmark we track has measured this model. That is not the same as measuring it and finding it wanting — we simply cannot rank it, so we do not.

## Our take

 editorial — not a measurement

The context-window outlier: 2M tokens at $1.25/$2.50, which is the cheapest long-context option from any major proprietary vendor. Same 200k tier threshold as the rest of the Grok line, doubling to $2.50/$5 above it — so the 2M window is only cheap in headline terms, and a genuinely 2M-token prompt bills entirely at the upper tier. Still, for bulk long-document processing the arithmetic is hard to beat. A multi-agent variant exists at the same rate.

### Strengths

 - 2M token context window — largest here
- $1.25/$2.50 short-context, very cheap
- Multi-agent variant at identical pricing
- Published tier threshold

### Weaknesses

 - Everything past 200k bills at $2.50/$5, so the big window is not cheap in practice
- Below the 4.5/4.6 line on capability
- No batch discount published

### Reach for it when

 - Bulk long-document ingestion
- Cheap very-long-context retrieval

### Avoid it if

 - You need frontier reasoning quality
- You assumed the headline rate applies at 2M tokens

Sources: docs.x.ai · arena.ai

### Every price dimension

| Input | $1.25 /M |
| --- | --- |
| Output | $2.50 /M |
| Cached input | $0.200 /M |
| Web search | $0.005 /call |

**Past 200,000 tokens the price changes.** Input goes to $2.50/M (2×) and output to $5.00/M. The headline rate does not apply to a long-context workload.

### Independent scores

| LMArena Elo | 1444.4 beta1 |
| --- | --- |

Sources are listed separately rather than averaged. Across the 62 models both have scored they correlate at r = 0.806 — close agreement overall, but four models rank very differently between them, and a blended score would hide exactly those.

#### Best rankings by task

 - htmlslides #12 of 34 1180
- asciiart #20 of 83 1205
- webapps #23 of 56 1181
- godotgamedev #26 of 43 1089
- svg #30 of 98 1203
- fullstack #30 of 59 1086

### Capability

| Context window | 2M |
| --- | --- |
| Input modes | text, image, file |
| Tool use | yes |
| Reasoning | optional |
| Knowledge cutoff | 2025-09-01 |
| Open weights | no |

### Provenance

| Price source | openrouter.ai |
| --- | --- |
| Fetched | 2026-08-24 |
| Quality data | unrated |
| Cross-checked | vendor page |

Grok 4.20 is a reasoning model from SpaceXAI with industry-leading speed and agentic tool calling capabilities. It combines the lowest hallucination rate on the market with strict prompt adherance, delivering...