# OpenRouter API cost and the cached rate you give up

> OpenRouter re-lists Anthropic models at identical headline rates but records no cached rate. What routing costs you on a repeated prompt.

URL: https://getculpa.com/openrouter-api-cost
Last reviewed: 2026-08-01
Rates effective: 2026-07-02

## Answer
OpenRouter re-lists Anthropic models at identical headline rates, $5.00 and $25.00 per million on Opus 4.7, but records no cached rate where the direct route offers one at $0.50. Culpa, a local-first LLM cost, margin, and forecast ledger, prices each call by the route that served it, so the difference stops being invisible.

## Why this happens
An aggregator looks free because the headline rates match. The difference sits in what the rate card omits. None of the four OpenRouter models in this price book record a cached input rate, including the two Anthropic re-listings whose direct equivalents carry a tenfold cached discount. On a workload with a large repeated prompt, that missing discount is the entire cost of routing, and no headline comparison reveals it.

## What this usually looks like
- Your routed spend runs above what the same models cost when you priced them direct.
- You budgeted a cache discount that never appeared on the invoice.
- The model behind a routed call changed without any deploy on your side.
- Comparing providers on headline rates alone showed no difference, yet the bills differ.

## Common mistakes
- Comparing an aggregator to a direct provider on the headline rate. Why it hurts: The headline matches while the cached rate doesn't, so a repeated prompt costs ten times more. Do instead: Compare on your own repeated-token share, not on the rate card's first two columns.
- Routing a heavy repeated-prompt workload through an aggregator. Why it hurts: That workload is exactly the one caching rescues, and the cached rate is what routing gives up. Do instead: Route exploratory and long-tail traffic, and take your stable high-volume path direct.
- Leaving a routed model unpinned. Why it hurts: The model behind a route can change under you, so both behaviour and rate move without a deploy. Do instead: Pin explicit models on routed traffic and treat a change as a release with a cost review.

## Self-check
- Measure what share of your routed prompt repeats across calls. That block gets no discount here.
- Price the same workload direct with the cached rate applied. The gap is what routing costs you.
- Check whether your routed models are pinned or floating.
- Confirm which provider actually served each routed call over the last month.
- Compare your routed spend against a direct quote before renewing any assumption about parity.

## The same Opus workload, routed and direct (illustrative)
A workload sending a 5,000-token repeated system prompt across 300,000 calls a month on Opus 4.7. Direct Anthropic offers a $0.50 per million cached read. OpenRouter records no cached rate for the same model.
  Repeated prompt volume: 300,000 x 5,000 = 1,500M tokens
  OpenRouter, no cached rate: 1,500 x $5.00 per million = $7,500
  Direct, at an 80% hit rate: (1,200 x $0.50) + (300 x $5.00) = $600 + $1,500 = $2,100
  Difference = $5,400 a month on an identical headline rate
  Both routes bill $5.00 input and $25.00 output, so no rate-card comparison shows this
$5,400 a month, invisible on any headline comparison, and it exists entirely because the routed listing records no cached rate.

## Cost figures
Every figure carries its confidence and its source. No figure on this site is provider-reported.
- $5.00 / $25.00 per million — OpenRouter Opus 4.7 rates, identical to the direct Anthropic headline [calculated] Source: Price book row for openrouter/anthropic/claude-opus-4.7, $0.005 and $0.025 per 1k, effective 2026-07-02, matching the anthropic/claude-opus-4-7 row.
- $2,100 to $7,500 — modelled monthly cost of a repeated-prompt workload, direct with caching versus routed without [estimated] Source: Both endpoints from the teardown arithmetic using real Opus 4.7 rates on both routes. A range because call volume and hit rate are modelled.

## FAQ
Q: Is OpenRouter more expensive than going direct?
A: On headline rates the Anthropic re-listings match exactly, $5.00 and $25.00 per million on Opus 4.7. The difference is that this price book records no cached rate for the routed listing, so a repeated prompt costs ten times what it would direct.

Q: What is the cheapest model on OpenRouter?
A: Hunyuan 3 Preview at $0.06 per million input and $0.21 output in this price book. DeepSeek V4 Flash is close behind at $0.09 and $0.18, and carries the flattest ratio of the four at about 2x.

Q: When does routing through an aggregator make sense?
A: For exploratory work, long-tail models you wouldn't otherwise integrate, and traffic where the repeated-prompt share is small. It makes least sense on a stable high-volume path with a large repeated prompt, which is exactly where caching pays.

## Sources
- OpenRouter models: https://openrouter.ai/models
- Anthropic pricing: https://platform.claude.com/docs/en/docs/about-claude/pricing

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