Which of GPT-5.6, Claude Fable 5, and Gemini 3.5 Pro is available today?

As of June 15, 2026, only Claude Fable 5 is generally available — Anthropic launched it on June 9, 2026 on Claude API, AWS Bedrock, Google Vertex AI, and Microsoft Foundry. Gemini 3.5 Pro was previewed at Google I/O 2026 on May 19 with general availability targeted for June 2026, and as of June 15 has not yet shipped — current expectation is a release within weeks. GPT-5.6 is rumored to be imminent (prediction markets give ~80% probability of release by June 30, 2026) but OpenAI's public catalog still lists GPT-5.5 and GPT-5.5 Pro as flagships. If you need a frontier model right now, Fable 5 is the only fully GA option.

How do their reported capabilities compare?

Claude Fable 5 leads published benchmarks: 95.0% SWE-Bench Verified, 80.3% on Anthropic's SWE-Bench Pro, and the Artificial Analysis Intelligence Index top spot as of mid-June. GPT-5.6 is reported in pre-release messaging to be a 'meaningful improvement' over GPT-5.5 but published benchmark numbers don't exist yet. Gemini 3.5 Pro previewed at Google I/O 2026 promised a 2-million-token context window (vs Fable 5's 1M, GPT-5.5's 200K-400K varying tiers), Deep Think reasoning mode, and stronger multimodal performance. Treat all GPT-5.6 capability claims and Gemini 3.5 Pro non-context numbers as marketing-stage pre-release; only Fable 5 has shipped and faced external benchmark evaluation.

What's the price comparison?

Claude Fable 5: $10 input / $50 output per million tokens, $1 cache read. The most expensive flagship currently on the market — double Opus 4.8 and double GPT-5.5's input price. GPT-5.5 (the current OpenAI flagship): $5 input / $15 output per million on the standard tier. GPT-5.6 pricing is unannounced; OpenAI's pattern across 5.x has been to keep similar tier pricing across point releases, so expect GPT-5.6 near $5/$15 unless OpenAI changes strategy. Gemini 3.5 Pro: expected at approximately 10x Gemini 3.5 Flash pricing, putting it around $15 input / $60 output per million tokens — pricier than Fable 5 on output. For pure budget, GPT-5.5 remains the cheapest frontier model; Fable 5 commands a premium for top quality; Gemini 3.5 Pro premium also targets quality.

Which should I choose for production this month?

Claude Fable 5, unless you have a specific reason to wait. It's the only one currently GA, has the strongest published benchmarks, and works across all three major cloud platforms (AWS, Google Cloud, Microsoft). Caveats: it's expensive ($10/$50) and the free-on-subscription window ends June 22, after which usage credits apply. If you're cost-sensitive and your tasks aren't at the frontier, GPT-5.5 at $5/$15 is excellent value and not going away. If you want a 2M-token context window and can wait 2-6 weeks for Gemini 3.5 Pro GA, that's a legitimate strategy. If you're tied to OpenAI for distribution reasons (existing API integration), wait for GPT-5.6 — it's imminent. For 'I need the best frontier model today and can afford it,' Fable 5 is the answer.

Quick Answer

GPT-5.6 vs Claude Fable 5 vs Gemini 3.5 Pro: Next-Gen Flagship Comparison (June 2026)

Published: June 15, 2026

GPT-5.6 vs Claude Fable 5 vs Gemini 3.5 Pro: Next-Gen Flagship Comparison (June 2026)

Three flagship AI models defining mid-2026: one shipped, two imminent. Claude Fable 5 went GA June 9. GPT-5.6 is rumored for late-June release. Gemini 3.5 Pro was previewed at Google I/O 2026 with June GA targeted. This page compares what we know about each, what’s verified vs marketing, and which to pick today.

Last verified: June 15, 2026.

TL;DR

Available now: Claude Fable 5 only.
Imminent (weeks): Gemini 3.5 Pro (Google I/O preview, GA targeted June 2026).
Rumored (weeks-to-month): GPT-5.6 (no official OpenAI announcement; prediction-market consensus ~80% by June 30).
Verified benchmark leader: Claude Fable 5.
Best value frontier-class today: GPT-5.5 (current OpenAI flagship, $5/$15).

What we actually know

Dimension	Claude Fable 5	GPT-5.6 (rumored)	Gemini 3.5 Pro (preview)
Status	GA June 9, 2026	Not announced; rumored late-June	Previewed May 19, GA targeted June 2026
Model ID	`claude-fable-5`	TBD	`gemini-3.5-pro` (preview)
Context window	1M tokens	TBD (GPT-5.5 is 200K-400K tiered)	2M tokens (preview)
SWE-Bench Pro	80.3% (Anthropic’s eval)	Unknown	Unknown (not yet eval’d public)
SWE-Bench Verified	95.0%	Unknown	Unknown
Input price	$10/Mtok	Unknown	~$15/Mtok (expected)
Output price	$50/Mtok	Unknown	~$60/Mtok (expected)
Cache read	$1/Mtok	Unknown	TBD
Reasoning mode	Extended thinking	Likely (5.5 has it)	Deep Think (preview)
Multimodal	Text + image	Text + image (likely audio/video)	Text + image + audio + video
Availability	Anthropic API, AWS Bedrock, Vertex AI, Microsoft Foundry	OpenAI API + likely Azure OpenAI	Vertex AI + Google AI Studio first

What’s actually shipped: Claude Fable 5

Anthropic launched Fable 5 on June 9, 2026 — the first publicly available Mythos-class model. Key facts:

Same core weights as Claude Mythos 5 (the safeguard-free sibling for trusted partners). Same capability, different refusal layer.
Pricing: $10 input / $50 output per million tokens. Double Opus 4.8, double GPT-5.5 input.
Free on Pro/Max/Team plans until June 22, 2026. Then usage credits required.
Available on all four major platforms — Anthropic API, AWS Bedrock, Google Vertex AI, Microsoft Foundry — from day one.
Benchmark performance: Tops the Artificial Analysis Intelligence Index, 80.3% on Anthropic’s SWE-Bench Pro, 95.0% SWE-Bench Verified.

For deeper coverage see Claude Fable 5 vs Opus 4.8: Should You Upgrade and Claude Fable 5 Paywall June 22, 2026.

What’s previewed but not shipped: Gemini 3.5 Pro

Google introduced Gemini 3.5 Pro at I/O 2026 (May 19) with general availability targeted for June 2026. Promised features:

2-million-token context window — double Fable 5’s 1M, eight-ish times GPT-5.5’s tiered context.
Deep Think reasoning mode — Google’s positioning against Anthropic’s Extended Thinking and OpenAI’s o-style reasoning.
Multimodal across text, images, audio, video with stronger reasoning over video than predecessors.
Pricing expected around $15 input / $60 output per million tokens — roughly 10x Gemini 3.5 Flash.
Available first via Vertex AI and Google AI Studio consumer plans (Google AI Pro $19.99/mo, Google AI Ultra $99.99/mo).

As of June 15, Gemini 3.5 Pro has not yet shipped GA. The model has been in internal testing/refinement; Pichai said “next month” at I/O, meaning June. Window remains open but it’s a few weeks late.

If you need 2M-token context, Gemini 3.5 Pro is the only realistic option in mid-2026. Fable 5 caps at 1M; even DeepSeek V4 Pro at 1M default leaves Gemini 3.5 Pro alone in 2M-territory.

What’s rumored but not announced: GPT-5.6

OpenAI’s public catalog as of June 15 still lists GPT-5.5 and GPT-5.5 Pro as current flagships. GPT-5.6 has not been formally announced. What’s circulating:

Internal messaging from OpenAI suggests GPT-5.6 is a “meaningful improvement” over 5.5 — consistent with the 5.x cadence (every 6-10 weeks).
Prediction markets give ~80% probability of release by June 30, 2026.
Expected focus: efficiency and safety improvements rather than radical capability jump.
Likely staged rollout across ChatGPT, Codex, and API.

OpenAI’s pattern in the 5.x series has been incremental: 5.4 → 5.5 added thinking improvements, 5.5 Pro added higher reasoning effort. 5.6 will likely continue the cadence.

The honest assessment: GPT-5.6 will probably ship before July 1 and will probably be roughly competitive with Fable 5 on selected benchmarks, but not radically ahead. If you’re on the OpenAI stack, wait two weeks before making a major architecture decision.

Capability per dollar

A useful framing for production teams:

Model	Status	Output cost/Mtok	Quality tier
Claude Fable 5	GA	$50	Frontier (verified)
Claude Opus 4.8	GA	$25	Near-frontier
GPT-5.5	GA	$15	Frontier-class (still strong)
Gemini 3.1 Pro	GA	$20-30 (tier-dependent)	Frontier-class
Gemini 3.5 Pro (expected)	Imminent	~$60	Frontier (claimed)
GPT-5.6 (expected)	Imminent	~$15-20 (expected)	Frontier (claimed)

The value play in mid-2026: GPT-5.5 at $5/$15 remains excellent. Use Fable 5 for the hardest 10-20% of tasks, GPT-5.5 (or DeepSeek V4 Pro at $0.27/$0.87) for everything else.

The “wait and see” play: Stay on Opus 4.8 / GPT-5.5 through the end of June, then re-evaluate when GPT-5.6 ships and Gemini 3.5 Pro GAs. Anthropic’s Fable 5 paywall transition (June 22) makes this a natural decision point.

Where each is best positioned

Claude Fable 5 wins on

Verified frontier capability — only one with public benchmarks confirming the claim.
Cross-platform availability — works on all four major clouds from day one.
Agentic refactor quality — SWE-Bench Pro 80.3% is real and matters.
Maturity of the Claude Code harness — the agent + model combo is production-tested.

Gemini 3.5 Pro will win on (when it ships)

2M-token context window — no competitor in this range.
Multimodal depth — Google’s video and audio handling traditionally strongest.
Google Cloud integration — Vertex AI + Workspace + Search backbone.
Price tier for Workspace customers — Google AI Ultra at $99.99 may bundle aggressively.

GPT-5.6 will likely win on

ChatGPT ecosystem — 600M+ weekly active users, distribution moat.
Cost-quality balance — if OpenAI keeps 5.x pricing intact, GPT-5.6 stays cheapest frontier.
Codex CLI integration — already the top Terminal-Bench performer at 83.4% with GPT-5.5.
Mature API ecosystem — broadest enterprise integrations.

Decision flow

Question 1: Do you need a frontier model in production today?
  Yes → Claude Fable 5 (only GA option).
  No  → Continue.

Question 2: Do you need 2M+ token context?
  Yes → Wait 2-6 weeks for Gemini 3.5 Pro GA, or use Fable 5 with prompt caching at 1M.
  No  → Continue.

Question 3: Are you OpenAI-standardized?
  Yes → Stay on GPT-5.5 today; expect to upgrade to GPT-5.6 in late June.
  No  → Continue.

Question 4: Is cost the binding constraint?
  Yes → GPT-5.5 or DeepSeek V4 Pro. Reserve Fable 5 for hard 10-20%.
  No  → Fable 5 with credits-based access post-June 22.

What to watch over the next 30 days

GPT-5.6 release — likely before June 30; published benchmarks will reset the landscape.
Gemini 3.5 Pro GA — Google has missed soft deadlines before; watch Vertex AI release notes.
Claude Fable 5 paywall switch June 22 — usage patterns will shift sharply; Anthropic may announce capacity expansion or restore-included-access dates.
Fable 5 third-party benchmarks — published benchmarks from independent evaluators (LiveCodeBench, Aider polyglot) over the next 2-4 weeks.

GPT-5.6 details in this article are pre-release rumors; treat as directional, not authoritative. Verify with OpenAI’s official announcements before production decisions.

GPT-5.6 vs Claude Fable 5 vs Gemini 3.5 Pro: Next-Gen Flagship Comparison (June 2026)

TL;DR

What we actually know

What’s actually shipped: Claude Fable 5

What’s previewed but not shipped: Gemini 3.5 Pro

What’s rumored but not announced: GPT-5.6

Capability per dollar

Where each is best positioned

Claude Fable 5 wins on

Gemini 3.5 Pro will win on (when it ships)

GPT-5.6 will likely win on

Decision flow

What to watch over the next 30 days

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