Claude Opus 5.5 API pricing: compare task costs in October 2026

Claude Opus 5.5 API pricing has two token rates, input and output. Anthropic's API, OpenRouter, WaveSpeedAI and Replicate all list $4 per million input tokens and $20 per million output tokens, so 10,000 uncached input tokens and 2,000 output tokens cost $0.08 on any of them. At the prices checked on October 21, 2026, SeedRouter's rates were at least 30% lower for both. The live table below shows the SeedRouter price for the same request. [1]

Thinking tokens, repeated conversation history and cache writes can change that bill. Use the tables below to estimate the whole task, or try Claude Opus 5.5 in the playground with the same rates.

To compare Opus 5.5 with the other Claude models on SeedRouter, see the Claude API pricing guide; this article compares Opus 5.5 alone across platforms.

What does Claude Opus 5.5 cost on SeedRouter?

These are SeedRouter's current rates. Prices refresh periodically; check the Claude Opus 5.5 pricing section before a large run. If a rate is unavailable, treat the estimate as unknown.

SeedRouter uses a prepaid balance with no subscription, credits never expire, and failed requests are not charged. For a completed request, use the actual token usage and the applicable account rate, then check usage history for the charge.

Use one complete set of applicable rates throughout your estimate. Do not combine one option's input price with another option's output or cache price.

How much less does SeedRouter cost than Anthropic and other APIs?

The SeedRouter row is read from the same rates that bill your account, so it changes when SeedRouter's prices change. The other rows are a dated snapshot of each platform's own pricing page, for standard processing before purchase fees and taxes. [1][2][3][4]

How much does one task cost?

For a request with no cache usage or separately priced tools:

cost = uncached input tokens × input rate / 1,000,000
     + output tokens × output rate / 1,000,000

At the checked $4 and $20 rates:

On SeedRouter, put the current rates from the table above into the same formula; at the October 21, 2026 prices, every row came out at least 30% lower. These are arithmetic examples, not promises about how many tokens a code review or research task will need. At those rates, each extra 1,000 output tokens adds $0.02, compared with $0.004 for 1,000 uncached input tokens.

A multi-turn task can include several requests. Add their costs rather than charging the initial prompt once and assuming the rest of the conversation is free.

When does prompt caching save money?

Caching helps when later requests reuse eligible prompt content. A cache write costs more than ordinary input; subsequent cache reads cost less. Anthropic and OpenRouter list Opus 5.5 cache reads at $0.20 per million tokens, with writes at $5 for five minutes or $8 for one hour. [1][2]

Consider the same 100,000-token reusable prefix across 20 requests, assuming one write followed by 19 cache hits before expiry, at those list rates:

SeedRouter prices the same cache categories, shown in its live table above. New input and all output tokens still add to those totals. This is not a whole-task bill. If the prefix changes or the cache expires, additional writes can reduce the saving. Check the response's cache usage fields rather than assuming repeated text produced a cache hit.

Use the API reference for cache_control and usage fields. Calculate cache writes and reads as their own categories; do not also count those same tokens as uncached input.

Why do thinking and output limits matter?

Claude Opus 5.5 uses adaptive thinking, and thinking is billed as output. The visible answer therefore does not account for every billed output token. Its max_tokens budget includes thinking as well as the answer. See the model API reference.

Start with the default effort and increase it when the task needs more reasoning. There is no fixed dollar surcharge for choosing an effort label: the cost depends on the tokens actually used. Compare completed task costs and acceptable results.

A generous output limit is a ceiling, not an amount automatically consumed. A limit that is too small can also truncate an answer and require another request. The Opus 5.5 prompting guide explains effort settings in more detail.

How do you send a request with an explicit budget?

Set an output ceiling and keep the model ID explicit:

curl https://api.seedrouter.ai/v1/messages \
  -H "x-api-key: $SEEDROUTER_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-5-5",
    "max_tokens": 2048,
    "messages": [{"role": "user", "content": "Explain three trade-offs of event sourcing in a short technical note."}]
  }'

Read the returned usage, including output and any cache fields. Save costs per completed task during your own evaluation, then multiply by expected task volume. The example above was not submitted as a paid request for this article.

Claude Opus 5.5 pricing questions

Is Claude Opus 5.5 cheaper on SeedRouter than on Anthropic's API?

Yes, at the prices checked on October 21, 2026: SeedRouter's input and output rates were at least 30% lower in every group, and the same holds against OpenRouter, WaveSpeedAI and Replicate. The comparison table recalculates the difference from SeedRouter's live rates.

Does a one-million-token context window cost extra?

SeedRouter charges Opus 5.5 one set of rates for every supported prompt length. A longer prompt still costs more because it contains more tokens, even without a higher unit price.

Which group should I choose on SeedRouter?

SeedRouter sells Opus 5.5 in more than one group, and the live table lists each group's rates. Without the optional X-SeedRouter-Group header a request uses your key's default; to choose a group, send that header as described in the API reference. Estimate with the chosen group's input, output and cache rates only.

Sources and comparison method

We operate SeedRouter. Other platforms' Claude Opus 5.5 API pricing was checked on October 21, 2026. Examples isolate token costs and do not include separately billed tools or purchases. No paid model requests were made for this comparison.

1. Anthropic pricing documentation — standard and cache prices.
2. OpenRouter Claude Opus 5.5 — published input, output and cache rates.
3. WaveSpeedAI Claude Opus 5.5 — published input, output and cache rates.
4. Replicate Claude Opus 5.5 — published input and output rates.