Gemini 3.1 Pro vs GPT-6.1 Sol
Gemini 3.1 Pro and GPT-6.1 Sol charge practically the same to read a 26.2K-token pull request ($0.0524). Above 200K tokens long-context rates apply, and GPT-6.1 Sol becomes the cheaper one. Both sit in the mid-range price tier, so the choice between them is about review quality more than budget. The benchmark cannot separate their recall: Gemini 3.1 Pro minus GPT-6.1 Sol is −22 pts (95% interval −36 pts to −9 pts).
Side by side
| Figure | Gemini 3.1 Pro | GPT-6.1 Sol |
|---|---|---|
| Price tier | Mid-range | Mid-range |
| Bugs caughtshare of known bugs | 67% | 89% (better) |
| False alarmsper clean PR | 0.8 (better) | 0.9 |
| Cost per reviewmeasured | $0.2499 | $0.0401 (better) |
| Cost per bug caught | $0.4134 | $0.0514 (better) |
| Exact linecatches on the expected lines | 89% | 95% (better) |
| Review timemean | 349s | 28s (better) |
| Typical review calllist price | $0.0814 | $0.0766 (better) |
| Input / 1M tokens | $2.00 | $2.00 |
| Output / 1M tokens | $12.00 | $10.00 (better) |
| Context window | 1M | 1.1M |
- Above 200K tokens, long-context rates mean GPT-6.1 Sol is the cheaper of the two.
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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gemini 3.1 Pro | 67% | 67% | 38% | 78% | 88% | 56% | 33% | 67% | 67% | 67% | 100% | 100% | 50% | 50% |
| GPT-6.1 Sol | 89% | 83% | 75% | 70% | 100% | 89% | 100% | 100% | 100% | 100% | 100% | 100% | 50% | 100% |
Of the 42 known bugs both were scored on, both caught 30 and neither caught 2. Gemini 3.1 Pro caught 2 bugs that GPT-6.1 Sol missed: 1 in Java and 1 in TypeScript, all of them concurrency bugs. GPT-6.1 Sol caught 8 bugs that Gemini 3.1 Pro missed: 2 in JavaScript, 2 in TypeScript, 1 in C#, 1 in Go, 1 in Kotlin and 1 in PHP.
On pull requests with no known bug, Gemini 3.1 Pro raised 0.8 false alarms per review and GPT-6.1 Sol 0.9. A measured review cost $0.2499 on Gemini 3.1 Pro, 6.2× the cost of $0.0401 on GPT-6.1 Sol.
| Pull request | Language · kind | Gemini 3.1 Pro | GPT-6.1 Sol |
|---|---|---|---|
| trpc/trpcfix(server): pass maxDurationMs timeout signal to subscription handlers | TypeScript · Concurrency | 1/1 | 0/1 |
| jhy/jsoupStore cached child els in Attributes, not field | Java · Concurrency | 1/2 | 0/2 |
| TanStack/queryfix(query-core): fix hydration bugs for already resolved promises | TypeScript · Logic | 0/1 | 1/1 |
| colinhacks/zodfeat(v4): parse input containing reference cycles | TypeScript · Resource handling | 0/1 | 1/1 |
| dotnet/orleansfix(serialization): cap codec allocations | C# · Logic | 0/1 | 1/1 |
| go-chi/chifeat: middleware.ClientIP, a replacement for middleware.RealIP | Go · Security | 0/1 | 1/1 |
| kotest/kotestFix DataClassEq comparator | Kotlin · Logic | 0/1 | 1/1 |
| nodejs/undicifeat: add configurable maxPayloadSize for WebSocket | JavaScript · Security | 0/1 | 1/1 |
| sindresorhus/p-throttleAdd `weight` option | JavaScript · Logic | 0/1 | 1/1 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · 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: Gemini 3.1 Pro and GPT-6.1 Sol.