Claude 3.5 Sonnet (2024-06-20) vs Claude Sonnet 4.6
Claude 3.5 Sonnet (2024-06-20) (Anthropic, 200,000-token context) versus Claude Sonnet 4.6 (Anthropic, 1,000,000-token context). Claude 3.5 Sonnet (2024-06-20) is cheaper by 0% on a blended token mix. Claude Sonnet 4.6 uniquely supports native reasoning mode. Across 1 public benchmark we tracked, Claude 3.5 Sonnet (2024-06-20) wins 0 and Claude Sonnet 4.6 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 — Claude 3.5 Sonnet (2024-06-20) vs Claude Sonnet 4.6
Claude 3.5 Sonnet (2024-06-20) and Claude Sonnet 4.6 are priced within 0% of each other, so cost alone is not the deciding factor. The comparison comes down to capabilities, context window, and benchmark performance on the specific task shape your workload demands.
Claude Sonnet 4.6 ships a 1,000,000-token context window, 5.0x larger than Claude 3.5 Sonnet (2024-06-20)'s 200,000 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 200,000 tokens, the extra context on Claude Sonnet 4.6 is insurance you may never use — and Claude 3.5 Sonnet (2024-06-20) may win on other axes.
On capability surface area, the models diverge: Claude Sonnet 4.6 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: claude-sonnet-4-6
provider: anthropic
fallback:
model: claude-3-5-sonnet-20240620
provider: anthropic
shadow: { sample_rate: 0.05 } # mirror 5% of traffic to compare quality live| Claude 3.5 Sonnet (2024-06-20) | Claude Sonnet 4.6 | |
|---|---|---|
| Input price | $3.00/M | $3.00/M |
| Output price | $15.00/M | $15.00/M |
| Context window | 200,000 | 1,000,000 |
| Max output | 8,192 | 64,000 |
| Function calling | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio input | — | — |
| Reasoning | — | ✓ |
| Prompt caching | ✓ | ✓ |
| Structured output | ✓ | ✓ |
| Pricing verified | May 7, 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 | Claude 3.5 Sonnet (2024-06-20) | Claude Sonnet 4.6 | Delta |
|---|---|---|---|
| Startup 10K requests/day | $1,800 /mo | $1,800 /mo | — |
| Mid-market 100K requests/day | $18,000 /mo | $18,000 /mo | — |
| Enterprise 1M requests/day | $180,000 /mo | $180,000 /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.
Your workload needs long context — Claude Sonnet 4.6 fits 1,000,000 tokens versus the other model's 200,000, enough headroom for full books, large codebases, or 100+ page documents in one shot.
Your tasks involve multi-step planning or math-heavy reasoning — Claude Sonnet 4.6 ships a native reasoning mode that explicitly thinks before responding, the other doesn't.
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 Claude 3.5 Sonnet (2024-06-20), switching to Claude Sonnet 4.6 means re-architecting that path (and vice versa).
- • Native reasoning mode
Capabilities both share (6)
- ✓ Function calling
- ✓ Vision input
- ✓ PDF input
- ✓ Streaming
- ✓ Structured output (JSON schema)
- ✓ Prompt caching
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 | Claude 3.5 Sonnet (2024-06-20) | Claude Sonnet 4.6 | Winner | Δ |
|---|---|---|---|---|
| mmlu | 88.7 | 89.3 | Claude Sonnet 4.6 | ~0 |
Migration considerations
Concrete differences to wire through your stack before you flip traffic from one to the other.
- Context window changes up 400% when moving from Claude 3.5 Sonnet (2024-06-20) (200,000) to Claude Sonnet 4.6 (1,000,000). Re-check any prompt that relies on cramming long history or documents.
- Max output tokens differ: 8,192 on Claude 3.5 Sonnet (2024-06-20) vs 64,000 on Claude Sonnet 4.6. Long-form generation tasks may truncate differently — adjust streaming UI and chunking accordingly.
- Claude Sonnet 4.6 has capabilities Claude 3.5 Sonnet (2024-06-20) lacks: Native reasoning mode. Worth wiring through the agent design before commit.
How to A/B test Claude 3.5 Sonnet (2024-06-20) vs Claude Sonnet 4.6 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 Claude 3.5 Sonnet (2024-06-20) primary, mirror 20% of traffic to Claude Sonnet 4.6 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 — Claude 3.5 Sonnet (2024-06-20) vs Claude Sonnet 4.6
What is the context window of Claude 3.5 Sonnet (2024-06-20) versus Claude Sonnet 4.6? ▾
Claude 3.5 Sonnet (2024-06-20) supports up to 200,000 tokens of context. Claude Sonnet 4.6 supports up to 1,000,000 tokens. Claude Sonnet 4.6 has the larger window by a factor of 5.0x, which matters for long-document RAG, multi-turn agent sessions, and tasks that need to keep an entire codebase in working memory.
Do Claude 3.5 Sonnet (2024-06-20) and Claude Sonnet 4.6 both support tool calling? ▾
Yes — both Claude 3.5 Sonnet (2024-06-20) and Claude Sonnet 4.6 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.
Which model supports prompt caching for cost reduction? ▾
Both Claude 3.5 Sonnet (2024-06-20) and Claude Sonnet 4.6 support prompt caching. Cached input tokens are typically discounted 50–90% versus uncached input, depending on the provider. For agents with a stable system prompt + retrieval context, the cached pricing tier is the real unit economics number to track.
When should I choose Claude 3.5 Sonnet (2024-06-20) over Claude Sonnet 4.6? ▾
On the data this page surfaces, Claude 3.5 Sonnet (2024-06-20) is the right pick when Claude Sonnet 4.6'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 Claude Sonnet 4.6 over Claude 3.5 Sonnet (2024-06-20)? ▾
Your workload needs long context — Claude Sonnet 4.6 fits 1,000,000 tokens versus the other model's 200,000, enough headroom for full books, large codebases, or 100+ page documents in one shot. Your tasks involve multi-step planning or math-heavy reasoning — Claude Sonnet 4.6 ships a native reasoning mode that explicitly thinks before responding, the other doesn't.
How do I A/B test Claude 3.5 Sonnet (2024-06-20) against Claude Sonnet 4.6 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.