Claude Opus 5.5 vs Gemini 3.8 Flash
Reading a 26.2K-token pull request costs $0.1048 on Claude Opus 5.5, 5.3× the $0.0197 it costs on Gemini 3.8 Flash. Claude Opus 5.5 is a frontier model and Gemini 3.8 Flash a mid-range one. The benchmark cannot separate their recall: Claude Opus 5.5 minus Gemini 3.8 Flash is +22 pts (95% interval +9 pts to +35 pts).
Side by side
| Figure | Claude Opus 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Price tier | Frontier | Mid-range |
| Bugs caughtshare of known bugs | 90% (better) | 68% |
| False alarmsper clean PR | 1.7 | 1.0 (better) |
| Cost per reviewmeasured | $0.1525 | $0.0862 (better) |
| Cost per bug caught | $0.1921 | $0.1166 (better) |
| Exact linecatches on the expected lines | 89% | 94% (better) |
| Review timemean | 33s (better) | 427s |
| Typical review calllist price | $0.1532 | $0.0287 (better) |
| Input / 1M tokens | $4.00 | $0.75 (better) |
| Output / 1M tokens | $20.00 | $3.75 (better) |
| Context window | 1M | 1M |
Head to head
The known bugs both were scored on, by who caught each in at least one run.
By language
| Model | All | TypeScript6 bugs | Go4 bugs | Java4 bugs | Rust4 bugs | C#3 bugs | JavaScript3 bugs | Kotlin3 bugs | PHP3 bugs | Python3 bugs | Ruby3 bugs | Swift3 bugs | C++2 bugs | C1 bug |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Claude Opus 5.5 | 90% | 100% | 50% | 78% | 100% | 100% | 100% | 67% | 100% | 100% | 89% | 100% | 100% | 100% |
| Gemini 3.8 Flash | 68% | 83% | 75% | 43% | 75% | 78% | 67% | 0% | 50% | 83% | 100% | 100% | 50% | 50% |
Of the 42 known bugs both were scored on, both caught 30 and neither caught 2. Claude Opus 5.5 caught 9 bugs that Gemini 3.8 Flash missed: 2 in Java, 2 in Kotlin, 1 in C++, 1 in JavaScript, 1 in PHP, 1 in Rust and 1 in TypeScript. Gemini 3.8 Flash caught one bug that Claude Opus 5.5 missed: 1 in Go.
On pull requests with no known bug, Claude Opus 5.5 raised 1.7 false alarms per review and Gemini 3.8 Flash 1. A measured review cost $0.1525 on Claude Opus 5.5, 77% more than $0.0862 on Gemini 3.8 Flash.
| Pull request | Language · kind | Claude Opus 5.5 | Gemini 3.8 Flash |
|---|---|---|---|
| colinhacks/zodfeat(v4): parse input containing reference cycles | TypeScript · Resource handling | 1/1 | 0/1 |
| ggml-org/llama.cpprpc : cache and reuse compute graphs | C++ · Security | 1/1 | 0/1 |
| kotest/kotestRefactor eventually to ensure wall-clock time usage | Kotlin · Error handling | 1/1 | 0/1 |
| ktorio/ktorKTOR-9171 Redesign ByteReadChannel.readUTF8Line API | Kotlin · Logic | 1/1 | 0/1 |
| mockito/mockitoAdd core API to enable Kotlin singleton mocking | Java · API misuse | 1/1 | 0/1 |
| nodejs/undicifeat: add configurable maxPayloadSize for WebSocket | JavaScript · Security | 1/1 | 0/1 |
| nushell/nushellreorganize nushell configuration | Rust · Error handling | 1/1 | 0/1 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · Security | 1/1 | 0/1 |
| jhy/jsoupStore cached child els in Attributes, not field | Java · Concurrency | 1/2 | 0/4 |
| go-chi/chifeat: middleware.ClientIP, a replacement for middleware.RealIP | Go · Security | 0/1 | 1/1 |
Defects caught over all runs: a PR reviewed three times with one known bug shows 3/3 when it was caught every time.
Every bug each was scored on: Claude Opus 5.5 and Gemini 3.8 Flash.