Grok 4.7 vs Claude Fable 5.1: Data Guide

52.6% Terminal-Bench-Science: Comparing Grok 4.7 and Claude Fable 5.1

Grok 4.7 remains unreleased in the supplied record, while Claude Fable 5.1 is live with third-party reported scores of 52.6% on Terminal-Bench-Science and pricing of $10 per million input tokens plus $50 per million output tokens; choose Fable 5.1 for documented access today, and treat Grok 4.7 as a watch-and-test candidate until xAI publishes its own benchmarks and price.

Updated 2026-09-16: Musk sketched a Grok roadmap positioning 4.7 at roughly Opus 5.0 level and previewing 4.8, 4.9, and Grok 5 (see the Update below).

Key Takeaways

• Claude Fable 5.1 has the stronger public evidence base. A September brief reported 52.6% on Terminal-Bench-Science 0.1 and 55.8% versus 42.0% on Terminal-Bench 4.0. The figures are third-party reports, not independently reproduced results.
• Grok 4.7 has a stronger release signal than a normal rumor. A dated build string, reported bot testing, and an official release estimate appeared in the record. None establishes public availability or final specifications.
• The 2.1 trillion parameter figure is unverified. Community posts attribute it to Elon Musk and position Grok 4.7 as roughly 40% larger than the reported 1.5 trillion-parameter Grok 4.6.
• Pricing currently favors certainty, not necessarily Grok. Fable 5.1 has a reported tariff. Grok 4.7 has only a repeated “up to 10× cheaper” claim with no confirmed price or comparison basis.
• Coding is the most promising use case for both models, but only Fable 5.1 has directly reported target-model results. Early Grok testing is too thin for a responsible verdict.
• The current recommendation is conditional. Use Fable 5.1 when reproducible public numbers and immediate access matter. Evaluate Grok 4.7 after its API, model card, and independent tests appear.

Grok 4.7 vs Claude Fable 5.1 at a Glance

Dimension	Grok 4.7	Claude Fable 5.1
Public status	Not shown as publicly released in the supplied record; a September 2 statement targeted release in 10 days from Musk	Reported live in September 2026 by a third-party model brief
Model scale	2.1 trillion parameters, repeatedly reported but unverified	Parameter count: Not yet confirmed
Coding evidence	No verified public Grok 4.7 benchmark; one pre-release bug test reported 27 of 105 bugs solved, provenance unconfirmed	52.6% on Terminal-Bench-Science 0.1, plus a reported 55.8% versus 42.0% result on Terminal-Bench 4.0
Input price	Not yet confirmed; “up to 10× cheaper” is an unverified claim, not a tariff	$10 per million input tokens, according to third-party launch coverage
Output price	Not yet confirmed	$50 per million output tokens, according to third-party launch coverage
Context window	Not yet confirmed	1 million tokens, according to a third-party comparison writeup; official confirmation is not present in the supplied record
Access	Official channel, API identifier, limits, and rollout path: Not yet confirmed	Reported public/API availability; official access terms should be checked with Anthropic

The table separates public documentation from community reporting. It does not treat a repeated leak as an official specification.

Capabilities and Model Design

Grok 4.7 is described as a larger successor to Grok 4.6. The recurring narrative says it uses 2.1 trillion parameters, supplemental training on SpaceX company data, slower serving, and improved token efficiency. These details are founder-attributed or community-repeated claims, not a published xAI model card.

The main proposed design idea is the Token-Efficiency Tradeoff. Musk’s reported framing says Grok 4.7 should answer more slowly than Grok 4.6 while using fewer tokens to complete work. That distinction matters for AI engineering teams. Tokens per second measure interactive latency. Total tokens per completed task affect cost and long-running agent budgets. Without a public tariff and controlled task traces, neither benefit can be calculated.

A related SpaceX Data Advantage is also unverified. Community posts describe supplemental training on engineering data from SpaceX. The record does not identify the dataset size, permitted data categories, training mixture, evaluation protocol, or measured improvement. Engineering-domain data could help with technical knowledge, but a parameter count or training-data claim does not prove better software execution.

Grok 4.7 also has a documented development problem. On September 11, Musk said the model needed a few more days after testing found that it could abandon difficult tasks too early and fail to check its work rigorously. The reported explanation is an RL Self-Check Issue, possibly caused by penalizing long answers too strongly.

Source: @HarshithLucky3

The delay is relevant to capability analysis. It suggests that the model was not considered ready for broad release at the original target. It does not prove a final weakness, because reinforcement-learning fixes can change behavior substantially before launch.

Claude Fable 5.1 is positioned around long-horizon reasoning and agent work. A third-party model page describes it as a public Mythos-class variant with text input and text output. Its reported 1-million-token context window would be relevant to repository analysis, extended specifications, and multi-step tool workflows, although the supplied record does not include an official Anthropic model card.

For an engineering team, the practical difference is evidence maturity. Grok 4.7 has a plausible capability thesis. Fable 5.1 has a documented product position and reported measurements.

Benchmarks and Evidence Quality

Claude Fable 5.1 currently leads this comparison on published-looking numbers, but the numbers require careful labeling. A September 2 industry brief reported 52.6% on Terminal-Bench-Science 0.1, described as more than twice the result of Fable 5. The same brief listed 55.8% versus 42.0% on Terminal-Bench 4.0. The excerpt does not fully define every comparator or testing condition, so these should be treated as third-party reported results rather than universal rankings. The brief is available here

A separate community post reported that Fable 5.1 led Cursor Bench, while Grok 4.6 scored 70.8% at roughly four times lower cost. That comparison concerns Grok 4.6, not Grok 4.7, and therefore cannot answer the target query. It does provide a useful baseline for why developers are interested in Grok’s price-performance profile. The post is here

Grok 4.7 has no verified public benchmark in the supplied record. One pre-release report attributed a result of 27 solved bugs out of 105 to a purported Grok 4.7 snapshot. The same report listed 19 solved bugs for another model. The model identity, harness, prompts, and reproducibility remain unverified. See the early test report

A reported bot error containing grok-4-7-0907 is stronger evidence of an internal build than a simple countdown post. It still does not prove that the build was production-ready or that its weights matched the final public model.

Source: @0x0SojalSec

The Evidence Gap is therefore decisive. Fable 5.1 can be evaluated through reported benchmark figures and a stated price. Grok 4.7 cannot yet be ranked responsibly against those figures.

Pricing and Token Economics

Claude Fable 5.1 is reported at $10 per million input tokens and $50 per million output tokens. The third-party reporting says the list price is unchanged from Fable 5. It also reports cache reads at 75% lower cost and typical overall savings of about 25%, with savings reaching about 45% on heavy agent runs. Those cache and workload figures are not independently verified in the supplied record.

Grok 4.7 has no confirmed input or output price. Several posts claim it could be up to 10 times cheaper than a competing frontier model. That wording does not identify a tariff, token direction, discount tier, context surcharge, or comparable service. It should not appear in a procurement spreadsheet as a price.

The correct economic comparison is therefore asymmetric:

1. Fable 5.1 has a known reported rate but a high output-token price.
2. Grok 4.7 has a possible efficiency thesis but no usable rate card.
3. Grok’s claimed token efficiency could reduce total task cost, but no public traces establish the reduction.
4. Fable’s reported cache pricing may matter more than headline output rates for repeated repository context.

For an AI engineering team, cost should be measured per completed task rather than per token alone. A fair test would use the same repository, tool budget, retry policy, context strategy, and acceptance criteria. Until Grok 4.7 is available, such a test is impossible.

Availability, Access, and Limits

Claude Fable 5.1 is reported as launched in August or September 2026, depending on the source’s publication wording. The supplied record supports treating it as the available model in this comparison. Official Anthropic access terms, regional limits, and final context documentation are not included, so those details should be checked directly through Anthropic’s app and API documentation.

The Claude Fable 5.1 catalog page identifies the model as a chat model, but Kie.ai does not currently host this model. It should not be treated as an API endpoint or availability guarantee.

Grok 4.7 has a more uncertain path. The record contains:

• An official estimate of “10 days” on September 2.
• Reports of stealth testing in the Grok Bot.
• A reported invalid model name containing grok-4-7-0907.
• A delay of several days after reinforcement-learning issues were found.
• A later community claim that the delay could extend another week.

Musk’s delay statement is the latest direct status signal in the supplied record. The original update is linked here

No confirmed Grok 4.7 API model ID, access tier, context window, public price, or official release note appears in the evidence. Builders should not design a production dependency around the leaked identifier.

For current Grok experimentation, a shipped predecessor may be more practical than waiting. The deeper analysis of the Grok 4.7 2.1T signal for AI builders explains why the leak is meaningful while keeping its technical claims separate from confirmed product facts.

Which One Should You Use?

Choose Grok 4.7 if:

• The team can wait for a public release and run its own acceptance tests.
• SpaceX-related engineering knowledge is central to the workload, and the claimed SpaceX Data Advantage becomes measurable.
• Token efficiency matters more than immediate access, and the final price supports the claim.
• The team wants to test a new model against repository-scale coding tasks rather than rely on launch claims.

Grok 4.7 should not be selected today solely because of its reported 2.1 trillion parameters. The RL Self-Check Issue shows why final post-training behavior matters more than scale.

Choose Claude Fable 5.1 if:

• The model must be available now through documented vendor channels.
• Coding or agent work needs a published starting point for evaluation.
• The team values a reported 1-million-token context window.
• Procurement requires a known price before deployment.
• Long-horizon reasoning is more important than speculative cost savings.

Fable 5.1 is not automatically superior on every task. It is the safer evidence-based choice because its public record is substantially fuller.

Frequently Asked Questions

Is Grok 4.7 better than Claude Fable 5.1?

Grok 4.7 cannot yet be judged as better because its public benchmarks are unverified; Claude Fable 5.1 has the stronger documented evidence in this comparison. Claims that Grok will exceed all current models remain predictions until independent tests are available.

Which is better for coding, Grok 4.7 or Claude Fable 5.1?

Claude Fable 5.1 is the evidence-based coding choice today because it has reported Terminal-Bench results, while Grok 4.7 has no confirmed public coding benchmark. Grok 4.7 may become competitive, but its early bug-test result is not enough to establish a ranking.

Is Grok 4.7 cheaper than Claude Fable 5.1?

Grok 4.7 has no confirmed price, although community posts claim a possible cost advantage; Claude Fable 5.1 is reported at $10 per million input tokens and $50 per million output tokens. The repeated “up to 10× cheaper” phrase is not a published tariff.

Is Claude Fable 5.1 available now?

Claude Fable 5.1 is reported as live from September 2026, while Grok 4.7 has not been shown as publicly released in the supplied record. Anthropic’s official app and API documentation remain the appropriate source for current access terms.

Does Grok 4.7 have 2.1 trillion parameters?

Grok 4.7 is repeatedly described as a 2.1 trillion-parameter model, but the figure remains unconfirmed by a public xAI model card. Parameter count alone would not establish better coding, reasoning, or agent performance.

What benchmarks compare Grok 4.7 and Claude Fable 5.1?

No verified head-to-head benchmark compares Grok 4.7 with Claude Fable 5.1; Fable 5.1 has reported Terminal-Bench results, while Grok 4.7 has only early, unverified testing signals. Any future comparison should disclose prompts, tool access, model settings, retries, and cost.

What to Watch Next

The next decisive signals are an official Grok 4.7 model card, a confirmed API price and context window, and independent coding tests that compare completed tasks rather than isolated scores. Anthropic’s benchmark methodology, cache pricing, and actual Fable 5.1 availability limits also deserve verification as the model matures.

Update — 2026-09-16

On 2026-09-14 Elon Musk outlined a forward roadmap that reframes Grok 4.7 as one step in a fast release cadence rather than a standalone launch. Per multiple secondhand summaries, Musk positioned Grok 4.7 as roughly matching Claude Opus 5.0 — better in some areas, weaker in others — with multimodal and image handling still needing work; Grok 4.8 as a "noticeable improvement"; Grok 4.9 as potentially reaching Astra/Fable class; and Grok 5 as possibly surpassing everything else (@mark_k, @notjazii, @AGTPinsights). These are non-official, single-thread paraphrases, not spec-sheet figures, and the Opus 5.0-level claim traces to a single-source read (@polymarketjapan). Notably, an Opus 5.0 comparison would still leave Grok 4.7 below the Fable/Astra tier that this article's benchmark discussion centers on.

Release timing stayed unsettled through mid-September. After the reported early-week target slipped, observers still floated a "hopefully this week" window and continued asking where the model was (@LuminaBench, @mark_k), and a rumor roundup revived the unverified grok-4-7-0907 internal name alongside the ~2.1T-parameter figure (Threads roundup). None of these adds a confirmed benchmark, price, or official model card, so the article's core verdict is unchanged: the roadmap sharpens expectations but supplies no verified Grok 4.7 numbers to compare against Claude Fable 5.1.

Try related models on Kie.ai: Claude Fable 5.1 (Coming Soon), Grok 4.6 and Claude Opus 5.