Claude Opus vs Sonnet: The Honest 2026 Comparison

The "Claude Opus vs Sonnet" question used to be straightforward: pay for Opus when quality matters, use Sonnet when cost matters. As of February 2026, that math shifted. Sonnet 4.6 became the first Sonnet to beat the previous-generation Opus on coding evaluations — a milestone that compressed the case for paying flagship prices for many production workloads. The question now is sharper: when is Opus 4.7 actually worth ~5× Sonnet's output cost?

We run both at scale across Respan's customer base. The honest answer below: Opus is worth it for specific workloads (long-horizon agentic coding, the hardest reasoning), and Sonnet is the default for everything else. This article is the side-by-side from running both in production.

TL;DR — when to pick each

Most production teams default to Sonnet 4.6 and reach for Opus only on specific high-stakes flows.

The two tiers, briefly

Both are part of Anthropic's Claude 4 family, named for jazz tones (Haiku → Sonnet → Opus, in increasing capability and price). All current Claude models include the full 1M-token context window at flat rates as of early 2026.

Claude Sonnet 4.6 is the balanced production tier. Anthropic's pitch: Sonnet should handle the vast majority of production workloads, with Opus reserved for the truly hardest tasks. The Feb 2026 milestone — Sonnet 4.6 beating prev-gen Opus on coding — was Anthropic explicitly compressing the case for the flagship.

Claude Opus 4.7 is the flagship. Strongest at long-horizon agentic coding, vision-heavy workflows, and tasks where the model needs to think very hard for a long time. The output token budget can also be larger — important for tasks producing long files or extensive analysis.

There's also Opus 4.6 (still available at the same price as 4.7) and Opus 3 (legacy, 3× more expensive than 4.7 — don't use it).

Pricing (May 2026)

Opus is ~67% more expensive on input and ~67% more expensive on output than Sonnet at the same context tier. The gap is not 5× as is sometimes claimed — it's closer to 1.67×. With prompt caching enabled (90% off cached input), the effective Opus cost on a stable system prompt converges with Sonnet's cost.

But for output-heavy workloads — long-form generation, agentic coding that produces many code lines, deep analysis — the output-token gap drives the cost. A workload that costs $1k/month on Sonnet 4.6 will cost roughly $1.67k/month on Opus 4.7, all else equal.

The one place this math changes dramatically: batch processing offers 50% off both Opus and Sonnet, and prompt caching offers 90% off cached input on both. With aggressive caching + batching, the absolute cost gap narrows, but the relative gap stays.

Capability differences

In production workloads we've measured:

• General-purpose chat / conversational AI: Sonnet 4.6 ≈ Opus 4.7 (no meaningful quality difference for users)
• Single-file coding edits: Sonnet 4.6 ≈ Opus 4.7 (Sonnet is sufficient)
• Multi-file refactors with clear specs: Sonnet 4.6 ≈ Opus 4.7 (small Opus edge in edge cases)
• Multi-tool agent runs >5 minutes: Opus 4.7 wins on reliability (lower retry rates, fewer lost-agent loops)
• Multi-tool agent runs >30 minutes: Opus 4.7 wins decisively (Sonnet is more likely to drift)
• Long-form analysis with deep reasoning: Opus 4.7 has small but consistent edge
• Vision-heavy workflows: Opus 4.7 is meaningfully better
• Hardest reasoning problems (math olympiad-level): Opus 4.7 has clear edge

The Feb 2026 milestone where Sonnet 4.6 beat previous-generation Opus on coding evals tells you something specific: for most coding work, the previous-generation flagship is now matched or surpassed by today's Sonnet. The case for paying Opus prices has compressed unless you're at the frontier of difficulty.

When Opus is structurally worth it

Three scenarios where we always reach for Opus 4.7:

1. Long-horizon coding agents (30+ minutes of autonomous work). Sonnet's per-step quality is now close to Opus, but Opus's stability over long runs is meaningfully better. Lost-agent rate over a 1-hour run is roughly 2× lower on Opus in our trace data.

2. Highest-stakes reasoning where every percentage point matters. Legal analysis, medical reasoning, financial modeling — anywhere a 2-3% accuracy improvement over Sonnet is worth 67% more cost.

3. Vision-heavy workflows. Opus 4.7 has a real lead on multi-frame video reasoning, complex diagram analysis, and OCR-plus-reasoning tasks.

Outside these scenarios, Sonnet 4.6 is the right call for most teams.

When Sonnet 4.6 is enough

The vast majority of production workloads:

• Customer support chatbots
• Single-step code generation / refactor
• Document summarization
• Data extraction
• Internal tools (RAG over docs, classification)
• Most agentic workflows (provided they're not 30+ minute autonomous runs)
• Real-time conversational AI

For these, Sonnet 4.6 delivers the same end-user quality at meaningful savings. The Feb 2026 Sonnet-beats-prev-gen-Opus milestone confirms this empirically.

Frank's take — when I actually pick which

Default to Sonnet 4.6 for production. It's the right answer for the vast majority of workloads. Don't pay for Opus until you have a specific reason.

Reach for Opus 4.7 in three specific scenarios:

1. Long-horizon agents (30+ min autonomous runs) — reliability premium is real
2. Highest-stakes reasoning where edge cases compound — legal, medical, financial
3. Vision-heavy workflows — measurable quality gap

Use Haiku 4.5 for high-volume background tasks — classification, extraction, simple summarization. At $1/$5 it's 5× cheaper than Sonnet, and quality on bounded tasks is competitive.

Use the Claude Max ($100/mo) consumer plan for personal coding work. If you're already paying for Max, you have Opus access at no marginal cost. Use it.

Use prompt caching aggressively. On a stable system prompt, cached input drops 90%, narrowing the absolute cost gap between Sonnet and Opus. Both models support it.

Use batch processing for offline workloads. 50% off both tiers. The relative gap stays, but absolute costs drop.

How to evaluate which you need

Don't trust this article. Trust the eval. Run your actual production traffic against both Sonnet 4.6 and Opus 4.7 for a week. Score for quality and measure cost. The classic finding: for >80% of teams, the quality gap on most tasks is too small to justify the cost gap; for the remaining specific flows, Opus is genuinely worth it.

What you'll typically find:

• General workloads: Sonnet 4.6 wins on cost-quality Pareto
• Long agent runs: Opus 4.7 wins on cost-quality Pareto (because retries on Sonnet eat into the savings)
• Vision-heavy: Opus 4.7 wins
• Frontier reasoning: Opus 4.7 wins

Then route each workload to the right tier via a gateway.

FAQ

Is Opus 4.7 better than Sonnet 4.6? For most general production workloads, the quality difference is too small to matter. Opus 4.7 wins on long-horizon agent runs, vision-heavy workflows, and the hardest reasoning. Sonnet 4.6 is sufficient for the vast majority of everything else.

How much more does Opus cost than Sonnet? Roughly 67% more on both input and output. Opus 4.7 is $5/$25 per 1M tokens; Sonnet 4.6 is $3/$15. With prompt caching and batching, the absolute gap narrows.

Why did Sonnet 4.6 catch the previous Opus? Anthropic shipped Sonnet 4.6 in Feb 2026 with material improvements specifically targeted at the coding workloads where Opus had previously led. The result: Sonnet 4.6 beats Opus 4.5 on most coding evaluations. The current Opus 4.7 has restored some of that lead but the compression is real.

Should I use Opus or Sonnet for coding? Sonnet 4.6 for most coding work — it's now competitive with previous-generation Opus and meaningfully cheaper. Opus 4.7 for long-horizon agentic coding runs (30+ minutes autonomous) where reliability over time matters more than per-step quality.

Should I use Opus or Sonnet for agents? Sonnet 4.6 for short-to-medium agent runs (under 30 minutes). Opus 4.7 for long-horizon agents where retry rate over time is the bottleneck.

Does Opus have a longer context window? No. As of 2026 both Opus 4.7 and Sonnet 4.6 ship with 1M-token context windows at flat rates. The context-window argument for Opus is gone.

Should I just use Haiku 4.5 if I want to save money? For high-volume background tasks (classification, extraction, simple summarization), yes. Haiku 4.5 at $1/$5 is 5× cheaper than Sonnet 4.6 and quality is competitive on bounded tasks. For anything customer-facing or quality-sensitive, Sonnet is the better default.

Is Opus worth it on a personal subscription? If you're already paying Claude Max ($100/mo), Opus is included and you should use it. The marginal cost is zero. If you're choosing between Pro ($20/mo, Sonnet only) and Max, the answer depends on whether your workflow benefits from Opus's specific strengths.

Can I use both Opus and Sonnet in the same app? Yes — and you should. Use a gateway to route by task type. Long agent runs to Opus, everything else to Sonnet, simple high-volume work to Haiku.

Related

• LLM Observability: The Complete Guide
• Claude vs ChatGPT (2026)
• Claude Code vs Cursor (2026)
• LLM Evals: How to Score, Compare, and Ship LLM Quality