Gemini 3.1 Pro vs GPT-5.6 Sol
Reading a 26.2K-token pull request costs $0.1048 on GPT-5.6 Sol, 2.0× the $0.0524 it costs on Gemini 3.1 Pro. Gemini 3.1 Pro is a mid-range model and GPT-5.6 Sol a frontier one. The benchmark cannot separate their recall: Gemini 3.1 Pro minus GPT-5.6 Sol is −5 pts (95% interval −21 pts to +11 pts).
Side by side
| Figure | Gemini 3.1 Pro | GPT-5.6 Sol |
|---|---|---|
| Price tier | Mid-range | Frontier |
| Bugs caughtshare of known bugs | 67% | 72% (better) |
| False alarmsper clean PR | 0.8 (better) | 1.2 |
| Cost per reviewmeasured | $0.2499 | $0.1127 (better) |
| Cost per bug caught | $0.4134 | $0.1732 (better) |
| Exact linecatches on the expected lines | 89% | 92% (better) |
| Review timemean | 349s | 50s (better) |
| Typical review calllist price | $0.0814 (better) | $0.1532 |
| Input / 1M tokens | $2.00 (better) | $4.00 |
| Output / 1M tokens | $12.00 (better) | $20.00 |
| Context window | 1M | 1.1M |
- Above 200K tokens, long-context rates mean the two cost the same.
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-5.6 Sol | 72% | 67% | 50% | 69% | 75% | 56% | 100% | 67% | 100% | 100% | 67% | 100% | 50% | 0% |
Of the 42 known bugs both were scored on, both caught 26 and neither caught 4. Gemini 3.1 Pro caught 6 bugs that GPT-5.6 Sol missed: 2 in TypeScript, 1 in C, 1 in Go, 1 in Ruby and 1 in Rust. GPT-5.6 Sol caught 6 bugs that Gemini 3.1 Pro missed: 2 in JavaScript, 2 in TypeScript, 1 in Go and 1 in PHP.
On pull requests with no known bug, Gemini 3.1 Pro raised 0.8 false alarms per review and GPT-5.6 Sol 1.2. A measured review cost $0.2499 on Gemini 3.1 Pro, 2.2× the cost of $0.1127 on GPT-5.6 Sol.
| Pull request | Language · kind | Gemini 3.1 Pro | GPT-5.6 Sol |
|---|---|---|---|
| rails/railsReimplement Action Cable redis adapter with redis-client | Ruby · Logic | 1/1 | 0/1 |
| traefik/traefikAdd the option to define custom cipher suites for backend serversTransport | Go · API misuse | 1/1 | 0/1 |
| trpc/trpcfix(server): pass maxDurationMs timeout signal to subscription handlers | TypeScript · Concurrency | 1/1 | 0/1 |
| withastro/astroPort Go's csrf protection | TypeScript · Logic | 2/2 | 0/1 |
| c-ares/c-aresEvent Thread could stall when not notified of new queries on existing connections that are in a bad state | C · Resource handling | 1/2 | 0/1 |
| nushell/nushellreorganize nushell configuration | Rust · Error handling | 1/2 | 0/1 |
| 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 |
| go-chi/chifeat: middleware.ClientIP, a replacement for middleware.RealIP | Go · Security | 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-5.6 Sol.