GPT-5.6 vs Grok 4.5: Coding Head-to-Head
GPT-5.6 vs Grok 4.5: OpenAI’s $5/$30 flagship against xAI’s $2/$6 price shot with 500k context. Pricing, speed and live one-shot coding outputs, community-voted.
July 2026 delivered two flagship launches within days of each other, aimed at the same developers with opposite theories of how to win them. OpenAI shipped the GPT-5.6 family — Sol, Terra and Luna — with Sol on top at $5 input / $30 output per million tokens (GPT-5.6 is here has the full launch picture). xAI answered with Grok 4.5: a 500k-token context window at $2 / $6, a rate card written specifically to undercut Opus 4.8 ($5/$25) and GPT-5.5 — never mind Sol. One sells capability. The other sells capability per dollar. Both are already running in our arena.
The price war, in numbers
| GPT-5.6 Sol | Grok 4.5 | |
|---|---|---|
| Price per 1M tokens (in / out) | $5 / $30 | $2 / $6 |
| Context window | No new headline number — OpenAI is selling capability, not context | 500k tokens |
| Speed | Deliberate — max effort spends real time thinking before it types | Fast — short generation times are half the launch pitch |
| Role | The capability flagship: “best model, whatever it costs” | The undercutter: flagship ambitions at commodity rates |
The output gap is the one that compounds: $30 against $6 is five to one. Generate the same 40k tokens of code and Sol bills $1.20 where Grok 4.5 bills $0.24. But list price is only half the bill — thinking models emit tokens you never paste into a project, and Sol at max effort emits plenty of them. That is why the arena tracks cost per task, not cost per million: what did this landing page actually cost to produce.
Speed is the second front
The two models also bet on opposite tempos. Grok 4.5 ships answers fast and xAI leans on that hard; GPT-5.6 Sol at max effort takes the long way — extended reasoning before the first line of code, wagering that the extra tokens buy structure a fast model skips. In the arena, tempo is not a vibe: every output card records the model’s generation time and dollar cost right next to the app it produced, so you can see exactly what the waiting bought.
List price is a claim. A running app is a receipt.
Same prompt, one shot, both live
Our method is deliberately boring: every model gets the identical published prompt, one attempt, no retries, and the raw output runs live in your browser — bugs included. The pairing is already up: GPT-5.6 Sol vs Grok 4.5 puts both on the landing-page challenge side by side, and compare mode hides the names until after you vote. What to look for:
- Structure under pressure — hero layout, responsive breakpoints and spacing are where fast-and-cheap usually cracks first.
- Working interactions — buttons that do something, nav that scrolls, forms that validate. One-shot code either wired it or it didn’t.
- The cost line — each output lists what it cost to generate; check whether Sol’s extra thinking bought anything Grok skipped.
You will notice I have not told you who is winning. That is deliberate: the verdict here is community votes on blind comparisons, and the tally moves every day as votes land. The leaderboard has the live standings — votes, cost per task, generation times — for both models against the full 20-family field.
Rates in this post are launch list prices as of July 9, 2026. The standings are live and shift daily — treat the leaderboard as the verdict, not this post.
Which one should you use?
- You pay per token at scale — Grok 4.5 is the aggressive default: flagship ambitions at $6 output, with 500k context absorbing repo-sized prompts. Whether the quality holds is precisely what the votes are for.
- You want the strongest one-shot — Sol at max effort is OpenAI’s biggest swing since GPT-5.5, but a 5× output premium has to survive blind voting against a model a fifth its price.
- You want to decide like an engineer — open the arena, run the pair on two or three challenges, judge the running apps, and vote. Your vote becomes part of the answer.
Frequently asked questions
Is Grok 4.5 better than GPT-5.6 for coding?
There is no fixed answer to print — this comparison is decided by community votes on blind, one-shot outputs, and the tally changes as votes land. What is fixed: Grok 4.5 costs $2/$6 per million tokens with a 500k context window, while GPT-5.6 Sol costs $5/$30. The live leaderboard on testingmodels.com shows the current standings for both.
How much cheaper is Grok 4.5 than GPT-5.6 Sol?
At list price, Grok 4.5 is 2.5x cheaper on input ($2 vs $5 per million tokens) and 5x cheaper on output ($6 vs $30). Real per-task cost also depends on how many tokens each model emits — models that think longer bill more output — so compare the cost-per-task numbers in the arena rather than rate cards alone.
What is GPT-5.6 Sol?
Sol is the flagship tier of OpenAI’s GPT-5.6 family, launched in July 2026 alongside the smaller Terra and Luna tiers. It is priced at $5 per million input tokens and $30 per million output tokens, and it runs in our coding arena at maximum thinking effort on the same one-shot prompts as every other model.
What context window does Grok 4.5 have?
Grok 4.5 ships with a 500,000-token context window, the largest headline context of the July 2026 flagship launches. Combined with $2/$6 pricing, xAI positioned it explicitly to undercut Anthropic’s Opus 4.8 and OpenAI’s GPT-5.5 and GPT-5.6 on cost.
Don’t take the post’s word for it
The arena runs every model’s real output live. Pick a challenge, go blind, and cast a vote that counts in the public tally.
Open the arena