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Head-to-head comparison

o3 vs Grok 4.20 Multi-Agent

o3 (OpenAI) and Grok 4.20 Multi-Agent (xAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 18 August 2026

As of 18 August 2026, Grok 4.20 Multi-Agent holds the stronger ModelCap Index position (#14 vs #37); Grok 4.20 Multi-Agent is 3.2× cheaper per output token ($2.50/1M vs $8.00/1M); and Grok 4.20 Multi-Agent offers the longer context window (2M vs 200K tokens).

Which should you choose?

Choose o3 if…

  • ModelCap publishes no field on which o3 leads Grok 4.20 Multi-Agent for this pair.

Choose Grok 4.20 Multi-Agent if…

  • you want the stronger overall ModelCap Index position — #14 against #37 (73.0 vs 55.1 points).
  • API cost matters — $2.50/1M output tokens against $8.00/1M, about 3.2× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.25/1M against $2.00/1M.
  • you need the longer context window — 2M tokens against 200K.
  • Arena coding is your yardstick — 1508 against 1460.
  • you want the more recently listed model — Grok 4.20 Multi-Agent was listed 31 March 2026, o3 16 April 2025.

o3 vs Grok 4.20 Multi-Agent: specs, pricing and context

Specification comparison of o3 and Grok 4.20 Multi-Agent
Fieldo3OpenAIGrok 4.20 Multi-AgentxAI
ModelCap Index position#37#14
Index score55.173.0
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$1.25
Output price / 1M tokens$8.00$2.50
Context window200K tokens2M tokens
Max output tokens100K—
API providers listed11
Weight accessAPI onlyAPI only
Input modalitiesImage, Text, FileText, Image, File
First listed16 April 202531 March 2026
PublisherOpenAIxAI

Evidence: 4 public benchmark observations across 4 boards · 2 public benchmark observations across 2 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: o3 vs Grok 4.20 Multi-Agent

Public benchmark boards where o3 or Grok 4.20 Multi-Agent has a published result
Boardo3Grok 4.20 Multi-AgentLeads
Arena codingArena (LMArena)14601453–146615081502–1514Beta · 0309Grok 4.20 Multi-Agent
ARC-AGI-2ARC Prize Foundation6.5%High—Only one result
SWE-benchSWE-bench (Princeton / SWE-agent team)58.4%—Only one result
BFCL V4UC Berkeley (Gorilla)63.1Prompt—Only one result
Artificial Analysis Intelligence IndexArtificial Analysis31.1intelligence-index—Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

o3 vs Grok 4.20 Multi-Agent: common questions

Is o3 better than Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent ranks higher on the ModelCap Index as of 18 August 2026: #14 against #37. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is o3 cheaper than Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent is cheaper on output tokens: $2.50/1M against $8.00/1M. Input tokens are $2.00/1M for o3 and $1.25/1M for Grok 4.20 Multi-Agent. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, o3 or Grok 4.20 Multi-Agent?

Grok 4.20 Multi-Agent has the larger context window: 2M tokens against 200K.

Which is better for coding, o3 or Grok 4.20 Multi-Agent?

Arena coding: o3 1460, Grok 4.20 Multi-Agent 1508 — Grok 4.20 Multi-Agent leads.

Are o3 and Grok 4.20 Multi-Agent open-weight models?

o3: API only. Grok 4.20 Multi-Agent: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run o3 and Grok 4.20 Multi-Agent?

ModelCap currently lists 1 API provider for o3 and 1 for Grok 4.20 Multi-Agent, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this o3 vs Grok 4.20 Multi-Agent comparison?

Every figure comes from the sealed ModelCap dataset published 18 August 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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