Gemini 4 Carbon vs Claude Fable 5.2: Price, Speed and Benchmarks Compared

Google's Gemini 4 Carbon and Anthropic's Claude Fable 5.2 are the two flagship agentic AI models of November 2026 — and they could hardly be priced further apart. Carbon costs $2 per million input tokens and $10 per million output tokens at its introductory price, while Fable 5.2 costs $8 and $40, four times as much. Yet on the benchmarks each company chooses to highlight, the contest is close: Fable 5.2 leads on Anthropic's FrontierCode test, while Carbon wins on AutomationBench. A flagship AI model is a vendor's most capable model, built for the hardest work — in this case long-horizon agentic tasks that run for hours rather than seconds — and this comparison puts the two flagships head to head on price, speed and the benchmarks that actually matter.

Gemini 4 Carbon: what Google launched

Gemini 4 Carbon became generally available on 10 November 2026, according to Google's DeepMind blog, for paying developers and enterprises through the Gemini API in AI Studio and Gemini for business, and for Google AI Ultra subscribers in the Gemini app, AI Mode and Antigravity. That is a sharp change from its previous availability: since 28 October, Carbon had been offered only to cyber defenders through the Fairwind programme. Google calls Carbon its strongest model, built for long-horizon agentic and cyber work, while adding that its sibling model Argon "remains the ideal choice for the majority of software engineering and knowledge work" — a clear signal that Carbon is aimed at the hardest, longest tasks rather than everyday coding.

Carbon's headline benchmark is AutomationBench, a test from Zapier of agentic automation ability, where Google reports a score of 53.9%. That figure is Google-reported, using Zapier's benchmark as reported by Google, so it should be read as a vendor claim rather than an independent result. Carbon is not available on the free tier, and its thinking tokens — the tokens the model uses to reason before answering — are billed as output tokens.

Claude Fable 5.2: what Anthropic launched

Claude Fable 5.2 launched a day earlier, on 9 November 2026, as the successor to Fable 5.1. Anthropic prices it at $8 per million input tokens and $40 per million output tokens, down from $10 and $50 for Fable 5.1 — a price cut that arrived with the new version. Cache reads cost $0.20 per million tokens. Anthropic says Fable 5.2 produces output "up to 30% faster" than Fable 5.1, and it offers an optional Fast mode that runs up to 2.5 times faster still, at $16 per million input tokens and $80 per million output tokens. Fast mode trades money for speed, and it is worth remembering that its output price is eight times Carbon's introductory output price.

Fable 5.2's headline benchmark is FrontierCode 2.0, where Anthropic reports a score of 49.1% at Xhigh effort. Anthropic's own comparison table puts Fable 5.1 at 32.4%, Opus 5.5 at 45.5%, GPT-6 Astra at 42.8% and Gemini 4 Carbon at 41.1% — but with a catch: Carbon's score was measured at Medium effort, while Fable 5.2's was measured at Xhigh effort. Effort settings change how much thinking a model is allowed to do before answering, so scores measured at different effort levels are not directly comparable. Every number in that table is Anthropic-reported, and the effort-setting difference must be stated alongside the scores.

Price comparison: the gap is the story

On price, there is no contest. Fable 5.2 costs four times Carbon's introductory price — $8 versus $2 per million input tokens, and $40 versus $10 per million output tokens. Even after Carbon's introductory pricing ends on 30 November 2026, when its price rises to $4 input and $20 output per million tokens from 1 December, Fable 5.2 is still twice as expensive. The caching picture narrows the gap slightly: Carbon's cached input is 95% off, costing $0.10 per million tokens during the introductory period and $0.20 afterwards, against Fable 5.2's cache-read price of $0.20 per million tokens. For a workload that reuses a lot of context, Carbon's cache discount is a real advantage. For a workload that generates a lot of fresh output, the output-token price dominates — and there Carbon is four times cheaper at intro pricing and twice as cheap at standard pricing.

	Gemini 4 Carbon	Claude Fable 5.2
Launch date	10 Nov 2026	9 Nov 2026
Input price / 1M tokens	$2 intro, $4 from 1 Dec	$8
Output price / 1M tokens	$10 intro, $20 from 1 Dec	$40
Cache reads / 1M tokens	$0.10 intro, $0.20 after	$0.20
Speed claim	Not stated	Up to 30% faster than Fable 5.1; Fast mode up to 2.5x at $16/$80
FrontierCode 2.0	41.1% (Medium effort, Anthropic-reported)	49.1% (Xhigh effort, Anthropic-reported)
AutomationBench	53.9% (Google-reported)	51.4% (Anthropic-reported)
Free tier	No	No

Two laptops side by side on a desk, one showing code and the other showing a document.

Benchmarks: each vendor wins its own test

The benchmark picture is a draw with an asterisk. On FrontierCode 2.0, Fable 5.2 leads at 49.1% against Carbon's 41.1% — but those scores were measured at different effort settings, Xhigh for Fable and Medium for Carbon, so the gap is not a clean head-to-head result. On AutomationBench, the comparison is cleaner: Anthropic's own table gives Fable 5.2 a score of 51.4% against Carbon's 53.9%, so Carbon wins that benchmark even on Anthropic's own numbers. The honest conclusion is that neither model leads on every test. Fable 5.2 looks stronger on the hardest coding benchmark when given maximum thinking time; Carbon looks stronger on agentic automation, and it does so at a quarter of the price.

That price point is what makes the comparison interesting for buyers. A model that costs four times as much needs to be better enough on the specific task at hand to justify the premium. For long-horizon coding work where FrontierCode-style ability matters most, Anthropic's numbers give Fable 5.2 a real edge. For automation workflows, long-running agent tasks and cyber work, Carbon's AutomationBench win combined with its price makes it the value pick. Readers who want the wider context should see our earlier flagship AI model comparison of Carbon against Opus 5.5 and GPT-6 Astra, our launch coverage of Gemini 4 Carbon, and the GPT-6 Astra benchmark scores that complete the flagship picture.

Speed and availability

On speed, only Anthropic has published a claim: Fable 5.2 is "up to 30% faster" than its predecessor, with Fast mode offering up to 2.5 times the speed at double the price. Google has published no comparable speed claim for Carbon, so no speed comparison can be made from the vendors' own statements. On availability, both models are aimed at paying customers, and neither is on a free tier, so the price comparison above is the price every user will actually pay.

A developer comparing two glowing screens in a dark office at night.

Which model should you choose?

Choose Carbon if your work is agentic automation, long-running agent tasks or cyber defence, or if cost is a deciding factor — at introductory pricing it delivers a benchmark win on AutomationBench for a quarter of Fable 5.2's price, and even at standard pricing it is half the cost. Choose Fable 5.2 if your work is the hardest frontier coding, where its FrontierCode lead at Xhigh effort is the strongest signal available. Choose Fast mode only when latency is the binding constraint, because at $16/$80 it is the most expensive option in this comparison by a wide margin.

Close-up of a keyboard with a notebook showing a handwritten comparison list.

Key Takeaways

Carbon launched 10 Nov 2026 and Fable 5.2 launched 9 Nov 2026; both are flagship agentic models aimed at long-horizon work, and neither is on a free tier.
Price is the biggest gap: Fable 5.2 at $8/$40 per million tokens is 4x Carbon's intro price ($2/$10) and 2x Carbon's standard price ($4/$20 from 1 Dec).
Fable 5.2 leads FrontierCode 2.0 at 49.1% vs Carbon's 41.1%, but the scores were measured at different effort settings (Xhigh vs Medium) and are Anthropic-reported.
Carbon wins AutomationBench 53.9% to 51.4% on Anthropic's own table — so Fable does not lead on every test.
Fable 5.2 is up to 30% faster than Fable 5.1, with an optional Fast mode up to 2.5x faster at $16/$80; Google published no comparable Carbon speed claim.
Carbon's intro pricing ends 30 November 2026; cost any December decision at the $4/$20 standard rate.

Conclusion

Gemini 4 Carbon and Claude Fable 5.2 are both serious flagship models, but they are not equally priced for equal work. Fable 5.2's FrontierCode lead makes it the pick for the hardest coding tasks, while Carbon's AutomationBench win and its much lower price make it the value pick for agentic automation and long-running work. The right choice depends on the task, not the brand — and with Carbon's introductory price ending on 30 November, the price gap that defines this comparison will narrow from four times to two. Test both on your own workload before committing, because vendor benchmarks, however honestly labelled, are no substitute for your own numbers.

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