Sonnet 5.5 vs Opus 5.5: Is Paying Double Worth It?

01 / The sticker price: $0.07 versus $0.14

For a request using 20,000 uncached input tokens and 3,000 output tokens, Claude Sonnet 5.5 costs $0.07 at Anthropic’s published standard rates. Claude Opus 5.5 costs $0.14 for identical usage. That is a 100% premium, not proof of twice the value. The useful question is whether the upgrade reduces retries, review time, or failed work enough to cover seven extra cents. These calculations use published API rates, not a verified CheapRelay price quote. ([anthropic.com](https://www.anthropic.com/claude-sonnet-5-5))

02 / The four-line token rate card

Anthropic’s published comparison lists these prices per million tokens. Keep the categories separate: a cache write is not an ordinary input charge, and cached tokens should not also be counted as uncached input. ([anthropic.com](https://www.anthropic.com/claude-sonnet-5-5))

• ■ Uncached input: Sonnet $2; Opus $4.
• ■ Output: Sonnet $10; Opus $20.
• ■ Cache writes: Sonnet $2.50; Opus $5.
• ■ Cache reads: Sonnet $0.10; Opus $0.20. ([anthropic.com](https://www.anthropic.com/claude-sonnet-5-5))

The receipts below are arithmetic examples, not measured workloads. They exclude taxes, external tools, and other charges. Actual token consumption can differ between models, so equal-token comparisons isolate price rather than predict task-level spending.

03 / Receipt one: 1,000 everyday development requests

Assume every request consumes 20,000 uncached input tokens and 3,000 output tokens. Across 1,000 requests, that becomes 20 million input tokens and 3 million output tokens.

• ■ Sonnet input: 20 × $2 = $40.
• ■ Sonnet output: 3 × $10 = $30.
• ■ Sonnet total: $70, or $0.07 per request.
• ■ Opus input: 20 × $4 = $80.
• ■ Opus output: 3 × $20 = $60.
• ■ Opus total: $140, or $0.14 per request.

The upgrade adds $70 per 1,000 requests under these assumptions. If both deliver equally usable results, Sonnet wins this receipt. If Opus uses fewer tokens or needs fewer attempts, recalculate with those observed quantities instead of assuming identical usage.

04 / Receipt two: cached context still has a bill

Now assume a session writes 100,000 tokens to cache once, reads that prefix ten times, adds 20,000 total uncached input tokens, and produces 30,000 output tokens. Assume every read hits a valid cache and the listed write rate applies.

• ■ Sonnet cache write: 0.1 × $2.50 = $0.25.
• ■ Sonnet cache reads: 1 × $0.10 = $0.10.
• ■ Sonnet fresh input and output: $0.04 + $0.30.
• ■ Sonnet session total: $0.69.
• ■ Opus equivalent: $0.50 + $0.20 + $0.08 + $0.60 = $1.38.

Cache charges contribute $0.35 of the Sonnet receipt. Ignoring them would understate this example’s cost by roughly 51%. When reconciling a bill, check actual cache hits and the applicable cache-write terms rather than treating repeated context as free.

05 / The upgrade threshold: buy fewer failures, not a label

Anthropic positions Sonnet for well-scoped everyday work and Opus for complex, open-ended tasks requiring sustained judgment. That is a useful testing hypothesis, not a guarantee for your repository. ([anthropic.com](https://www.anthropic.com/claude-sonnet-5-5))

At the first receipt’s prices, two Sonnet attempts cost the same as one Opus attempt: $0.14. Opus breaks even on API spend if it reliably replaces more than two equivalent Sonnet attempts. Alternatively, using an assumed developer cost of $60 per hour, the $70 monthly premium needs to save 70 minutes across those 1,000 requests. Neither outcome is an observed benchmark.

06 / A 10% escalation budget before an all-Opus switch

Consider 1,000 tasks: 900 handled directly by Sonnet and 100 routed directly to Opus. At the example’s fixed token counts, the bill is $63 + $14 = $77. Running Sonnet first on all tasks, then escalating 100, costs $70 + $14 = $84 instead. Routing and retrying are different receipts.

CheapRelay’s supplied service details describe pay-as-you-go billing for actual tokens, including cache reads and writes, without a monthly subscription. Its live model rates were not independently verified here; substitute those rates before budgeting. Sign up for CheapRelay to run a small comparison on your own tasks.

Start with Sonnet as the budget baseline. Pay for Opus where recorded acceptance rates and review time justify the premium—not simply because it occupies the higher tier.