The Vibe Father
Model Comparison
Grok 4.5 is the new arrival, released July 9, 2026, and it comes in swinging on price. GPT-5.5 is OpenAI's established standard — the Terminal-Bench leader on our board and a known quantity teams already trust. So this is the value upstart against the incumbent: does Grok's aggressive pricing buy you a real seat at the table, or is GPT-5.5's proven muscle worth the premium? We run both live at /benchmarks.
What each one wins
Grok 4.5 wins on price and speed, decisively. xAI priced it at $2/$6 per million — that $6 output rate is remarkably cheap for a model this recent — and it streams at 91 tokens per second, brisk enough for comfortable interactive work. On capability it shows up where it counts most for algorithmic tasks: its 87.4 on LiveCodeBench is a strong contest-and-algorithm number, right in the mix with far more expensive models. For a value-first pick, that combination is compelling.
GPT-5.5 wins on breadth and proven muscle. It owns the top Terminal-Bench score on our board at 83.4 — the agentic-shell strength that separates a code writer from an agent that can actually drive your dev environment. It also has published SWE-bench (80.6) and Terminal-Bench figures, giving you a full, verified scorecard to plan around. Grok 4.5, being fresh, has fewer numbers on our board so far, which matters if you're routing serious work.
The numbers side by side
Our Vibe Coding Index weights SWE-bench Verified at 40%, Terminal-Bench and LiveCodeBench at 30% each. Grok 4.5 has no published SWE-bench or Terminal-Bench score on our board yet — it's a brand-new release, and we won't invent numbers. GPT-5.5's price varies by access tier.
| Model | SWE-bench Verified | Terminal-Bench | LiveCodeBench | Price (in/out per M) | Speed (tok/s) |
|---|---|---|---|---|---|
 Grok 4.5 | not yet published | not yet published | 87.4 | $2 / $6 | 91 |
 GPT-5.5 | 80.6 | 83.4 | 85.3 | varies by tier | — |
The one head-to-head we can make cleanly, Grok wins: 87.4 to 85.3 on LiveCodeBench, at a much lower and fully transparent price. But GPT-5.5 has a complete, verified scorecard including a board-topping Terminal-Bench, and Grok's SWE-bench and Terminal-Bench are simply not published yet. That's the honest state of play for a model one day old on our board.
We want to be careful not to overclaim on Grok's behalf, and equally careful not to dismiss it. A strong LiveCodeBench score tells you a model is good at self-contained algorithmic problems — competitive-programming-style challenges where the code is written fresh and judged against test cases. It does not automatically tell you how the same model handles repo surgery (SWE-bench) or long agentic shell sessions (Terminal-Bench), which are different skills that stress different muscles. Plenty of models are excellent contest solvers and merely average at navigating a real codebase, or vice versa. So Grok's 87.4 is genuine evidence of strength in one lane and no evidence either way in the other two. GPT-5.5, having posted numbers across all three, gives you the fuller picture — and that completeness is itself a feature when you're deciding where to route production work.
The price math
On our reference heavy month of 50M input and 10M output tokens, Grok 4.5 runs 50 × $2 + 10 × $6 = $160/month. GPT-5.5's tiered pricing lands well above that at any tier. For a model that already beats GPT-5.5 on the one benchmark they share, Grok's cost is genuinely disruptive — this is the "value upstart" claim earning itself honestly on price. We put the full budget picture in our cheapest coding models guide.
Who should pick which
Pick Grok 4.5 for algorithmic and contest work on a budget, and for anyone testing the water on a new engine without committing much money. Its 87.4 LiveCodeBench is a real strength, and at $2/$6 with 91 tok/s it's cheap and quick enough to run at volume. If your work leans toward LiveCodeBench-style problems — competitive coding, algorithmic puzzles, self-contained challenges — Grok is a legitimately strong, cheap choice today.
Pick GPT-5.5 when you need a proven full scorecard, and especially for terminal-native work. Its board-topping Terminal-Bench is the muscle for long autonomous shell sessions, and its published SWE-bench gives you confidence on repo surgery that Grok can't yet match on paper. If you're routing production agents and want verified strength across the board, the incumbent's completeness is worth the premium — for now.
Grok's missing numbers aren't a knock, just a timing artifact; they'll land on the leaderboard as they publish, and we'll reassess. Until then, the honest move is what The Vibe Father is built for: run Grok in the algorithmic seat where it already wins, keep GPT-5.5 for terminal-heavy work, and let each earn its keep. See the seats in the best model for each agent role.
Verdict
The value upstart lands a real punch: Grok 4.5 is cheaper, brisk, and already ahead of GPT-5.5 on LiveCodeBench — a genuinely strong debut. But GPT-5.5 remains the safer all-rounder with a complete, verified scorecard and the top Terminal-Bench score on our board, and Grok's SWE-bench and Terminal-Bench numbers aren't published yet. For algorithmic work on a budget, Grok is compelling now; for proven breadth and terminal muscle, GPT-5.5 still earns its place. Read the full cases in our Grok 4.5 review and GPT-5.5 review, and watch both on the live leaderboard.
