Grok 3 vs Grok 4.20 Multi Agent beta 0309
Grok 3 (Azure AI Foundry, 131,072-token context) versus Grok 4.20 Multi Agent beta 0309 (xAI, 2,000,000-token context). Grok 4.20 Multi Agent beta 0309 is cheaper by 56% on a blended token mix. Grok 4.20 Multi Agent beta 0309 uniquely supports vision input and prompt caching. Across 1 public benchmark we tracked, Grok 3 wins 0 and Grok 4.20 Multi Agent beta 0309 wins 1. Use the live calculator below to plug your real usage shape into both, then route the winner via Agent Command Center for shadow A/B without code changes.
Bottom line — Grok 3 vs Grok 4.20 Multi Agent beta 0309
Grok 3 and Grok 4.20 Multi Agent beta 0309 target overlapping workloads but differ sharply on economics. Grok 4.20 Multi Agent beta 0309 runs roughly 56% cheaper on a blended input-plus-output token mix, which translates to approximately $8,400 per month at mid-market volume (100K requests/day). The gap compounds at enterprise scale, making the cost axis the first filter most teams apply when deciding between these two models.
Grok 4.20 Multi Agent beta 0309 ships a 2,000,000-token context window, 15.3x larger than Grok 3's 131,072 tokens. That headroom matters for long-document RAG pipelines, multi-turn agent sessions that accumulate tool-call history, and codebases where the entire repository needs to fit in a single prompt. If your average prompt stays under 131,072 tokens, the extra context on Grok 4.20 Multi Agent beta 0309 is insurance you may never use — and Grok 3 may win on other axes.
On capability surface area, the models diverge: Grok 4.20 Multi Agent beta 0309 supports vision input where the other does not; Grok 4.20 Multi Agent beta 0309 supports prompt caching where the other does not; Grok 4.20 Multi Agent beta 0309 supports native reasoning mode where the other does not. These differences are binary — either your workload needs the capability or it does not. Check whether any critical path in your agent pipeline depends on a capability only one model provides before committing to a migration.
For teams evaluating both models, the recommended path is a shadow A/B test: route production traffic through an OpenAI-compatible gateway, mirror a percentage to the candidate model, score both responses with an automated evaluator (faithfulness, tool-call correctness, latency), and compare cohort-level metrics over two weeks. Future AGI Agent Command Center supports this pattern with a single `base_url` change and built-in evaluators from the ai-evaluation SDK.
Live workload comparison
Same workload run through both models. The cheaper one is highlighted.
strategy: cost-optimized
primary:
model: grok-4-20-multi-agent-beta-0309
provider: xai
fallback:
model: grok-3
provider: azure-ai-foundry
shadow: { sample_rate: 0.05 } # mirror 5% of traffic to compare quality live| Grok 3 | Grok 4.20 Multi Agent beta 0309 | |
|---|---|---|
| Input price | $3.00/M | $2.00/M |
| Output price | $15.00/M | $6.00/M |
| Context window | 131,072 | 2,000,000 |
| Max output | 131,072 | 2,000,000 |
| Function calling | ✓ | ✓ |
| Vision | — | ✓ |
| Audio input | — | — |
| Reasoning | — | ✓ |
| Prompt caching | — | ✓ |
| Structured output | — | — |
| Pricing verified | Jun 2, 2026 | Jun 2, 2026 |
Benchmark comparison
Side-by-side public benchmark scores. Greener bar = winner.
Cost at scale: monthly spend at three usage volumes
Estimated monthly cost assuming 1,000 input + 200 output tokens per request — a realistic chat-agent shape. Adjust your own usage in the calculator at the top of this page for an exact number.
| Scale | Grok 3 | Grok 4.20 Multi Agent beta 0309 | Delta |
|---|---|---|---|
| Startup 10K requests/day | $1,800 /mo | $960 /mo | $840/mo |
| Mid-market 100K requests/day | $18,000 /mo | $9,600 /mo | $8,400/mo |
| Enterprise 1M requests/day | $180,000 /mo | $96,000 /mo | $84,000/mo |
At enterprise scale (1M requests/day), a difference of even ~10% in unit price compounds into thousands of dollars per month. Cached input pricing and batch tiers can shift this further — both are surfaced on each model's own page.
When to choose which
Picked from the data above — not vendor marketing. Match the rules to your workload, not the other way around.
You're cost-sensitive at scale — Grok 4.20 Multi Agent beta 0309 runs ~56% cheaper on a blended in+out token mix, compounding into thousands of dollars per month at production volume.
Your workload needs long context — Grok 4.20 Multi Agent beta 0309 fits 2,000,000 tokens versus the other model's 131,072, enough headroom for full books, large codebases, or 100+ page documents in one shot.
Your inputs include screenshots, diagrams, or product photos — Grok 4.20 Multi Agent beta 0309 accepts image input natively, the other doesn't.
Your tasks involve multi-step planning or math-heavy reasoning — Grok 4.20 Multi Agent beta 0309 ships a native reasoning mode that explicitly thinks before responding, the other doesn't.
You re-send the same large system prompt across requests — Grok 4.20 Multi Agent beta 0309 supports prompt caching, cutting input cost on repeat hits.
On arena-elo, Grok 4.20 Multi Agent beta 0309 scores 71.0 points higher — if your workload pattern matches that benchmark's task shape, the gap is meaningful.
Capability diff — what you gain and lose on the swap
A specific list of what each model has that the other doesn't. If your workload depends on a row in Only Grok 3, switching to Grok 4.20 Multi Agent beta 0309 means re-architecting that path (and vice versa).
- • Vision input
- • Prompt caching
- • Native reasoning mode
Capabilities both share (2)
- ✓ Function calling
- ✓ Streaming
Benchmark winners — by the numbers
For each public benchmark that has scores for both models, the higher score and the size of the gap. Benchmarks are noisy — treat anything under a 2-point delta as effectively tied.
| Benchmark | Grok 3 | Grok 4.20 Multi Agent beta 0309 | Winner | Δ |
|---|---|---|---|---|
| arena-elo | 1402.0 | 1473.0 | Grok 4.20 Multi Agent beta 0309 | +71.0 |
Migration considerations
Concrete differences to wire through your stack before you flip traffic from one to the other.
- Context window changes up 1426% when moving from Grok 3 (131,072) to Grok 4.20 Multi Agent beta 0309 (2,000,000). Re-check any prompt that relies on cramming long history or documents.
- Max output tokens differ: 131,072 on Grok 3 vs 2,000,000 on Grok 4.20 Multi Agent beta 0309. Long-form generation tasks may truncate differently — adjust streaming UI and chunking accordingly.
- Grok 4.20 Multi Agent beta 0309 has capabilities Grok 3 lacks: Vision input, Prompt caching, Native reasoning mode. Worth wiring through the agent design before commit.
- Provider changes from Azure AI Foundry to xAI. API authentication, rate-limit policy, regional availability, and billing all shift. Most teams route through an OpenAI-compatible gateway (e.g., Future AGI Agent Command Center) so the swap is a single `base_url` change instead of an SDK rewrite.
How to A/B test Grok 3 vs Grok 4.20 Multi Agent beta 0309 in production
If you're stuck between the two, run them side-by-side on real traffic. Four steps the Future AGI team uses internally:
- 1. Point your existing OpenAI SDK at
https://gateway.futureagi.com/v1. No code change beyondbase_urland a virtual key. - 2. Mark Grok 3 primary, mirror 20% of traffic to Grok 4.20 Multi Agent beta 0309 in shadow mode. Both responses are logged; only the primary is served to users.
- 3. Score every shadow response with an evaluator — faithfulness, tool-call correctness, response latency, cost. Built-in evaluators in ai-evaluation cover the common axes.
- 4. Compare cohort-level metrics after two weeks. Switch primary when the candidate wins on what matters to your workload — and stays within your latency budget.
Full walkthrough on the Agent Command Center page.
FAQ — Grok 3 vs Grok 4.20 Multi Agent beta 0309
Which is cheaper, Grok 3 or Grok 4.20 Multi Agent beta 0309? ▾
Grok 4.20 Multi Agent beta 0309 is cheaper by roughly 56% on a blended input + output token mix. Input prices are $3.00/M for Grok 3 versus $2.00/M for Grok 4.20 Multi Agent beta 0309; output prices are $15.00/M versus $6.00/M. The exact savings depend on your input:output ratio — use the live calculator above to plug in your own request shape.
What is the context window of Grok 3 versus Grok 4.20 Multi Agent beta 0309? ▾
Grok 3 supports up to 131,072 tokens of context. Grok 4.20 Multi Agent beta 0309 supports up to 2,000,000 tokens. Grok 4.20 Multi Agent beta 0309 has the larger window by a factor of 15.3x, which matters for long-document RAG, multi-turn agent sessions, and tasks that need to keep an entire codebase in working memory.
Do Grok 3 and Grok 4.20 Multi Agent beta 0309 both support tool calling? ▾
Yes — both Grok 3 and Grok 4.20 Multi Agent beta 0309 support native function calling. Both also support structured output via JSON schema, so an agent can be ported between them with the same tool definitions.
Can Grok 3 and Grok 4.20 Multi Agent beta 0309 process images? ▾
Grok 4.20 Multi Agent beta 0309 accepts native image input. Grok 3 does not — you would need to route image-heavy workloads through Grok 4.20 Multi Agent beta 0309 or add a separate vision model in front of Grok 3.
Which model supports prompt caching for cost reduction? ▾
Grok 4.20 Multi Agent beta 0309 supports prompt caching; the other does not. If your agent has a stable system prompt + retrieval context block that repeats across requests, Grok 4.20 Multi Agent beta 0309 gives you a 50–90% discount on those repeated input tokens at the provider level.
When should I choose Grok 3 over Grok 4.20 Multi Agent beta 0309? ▾
On the data this page surfaces, Grok 3 is the right pick when Grok 4.20 Multi Agent beta 0309's lower price or different capability profile aren't a fit for your workload. Run the live calculator above against your actual usage shape to confirm.
When should I choose Grok 4.20 Multi Agent beta 0309 over Grok 3? ▾
You're cost-sensitive at scale — Grok 4.20 Multi Agent beta 0309 runs ~56% cheaper on a blended in+out token mix, compounding into thousands of dollars per month at production volume. Your workload needs long context — Grok 4.20 Multi Agent beta 0309 fits 2,000,000 tokens versus the other model's 131,072, enough headroom for full books, large codebases, or 100+ page documents in one shot. Your inputs include screenshots, diagrams, or product photos — Grok 4.20 Multi Agent beta 0309 accepts image input natively, the other doesn't. Your tasks involve multi-step planning or math-heavy reasoning — Grok 4.20 Multi Agent beta 0309 ships a native reasoning mode that explicitly thinks before responding, the other doesn't. You re-send the same large system prompt across requests — Grok 4.20 Multi Agent beta 0309 supports prompt caching, cutting input cost on repeat hits. On arena-elo, Grok 4.20 Multi Agent beta 0309 scores 71.0 points higher — if your workload pattern matches that benchmark's task shape, the gap is meaningful.
How do I A/B test Grok 3 against Grok 4.20 Multi Agent beta 0309 in production? ▾
Route both through an OpenAI-compatible gateway like Future AGI Agent Command Center with shadow mode enabled. Send 100% of traffic to your primary model, mirror 10–20% to the candidate, score every response with an evaluator (faithfulness, tool-call correctness, response time), and compare cohort-level metrics for two weeks. Switch when the candidate wins on the metrics that matter to your workload and stays within your latency budget.