Claude Fable 5 vs GPT-5.6 Sol: Choosing Between Two Flagships
Both models became their vendor's flagship within the last two months, but their pricing structures couldn't be more different -- Fable 5 costs more on output, Sol is cheaper across the board. Here's the spec comparison, a cost estimate, and how to choose.
Claude Fable 5 officially launched on 2026-06-09. GPT-5.6 Sol launched with the GPT-5.6 family on 2026-07-09. As of this update (2026-08-08), both remain their respective vendor's flagship-tier model, with no newer version having replaced either.
Last verified: 2026-08-08.
Spec and Price Comparison
Pricing and context window figures come from official pricing pages and the LiteLLM authoritative pricing table. See the methodology note below for the SWE-Bench Pro score caveat -- Sol's equivalent score hasn't been separately published.
| Model | Input price (per million tokens) | Output price (per million tokens) | Context window | SWE-Bench Pro |
|---|---|---|---|---|
| Claude Fable 5 | $10.00 | $50.00 | ~1,000,000 tokens | 80.3% (official methodology, see note below) |
| GPT-5.6 Sol | $5.00 | $30.00 | ~1,050,000 tokens | Not separately published by OpenAI |
Three Things Worth Knowing
The scoring methodology: 80.3% isn't a neutral reproduction
Fable 5's 80.3% on SWE-Bench Pro was produced using Anthropic's own evaluation scaffolding, and independent evaluators' reproductions differ from the official number. That's not an accusation of a fabricated score -- the evaluation method itself affects results. The full breakdown lives in our dedicated piece, "SWE-Bench Pro: How Fable 5's Score Was Actually Calculated" -- we won't re-argue it here. Sol's side is simpler: OpenAI hasn't separately published a SWE-Bench Pro score for it, we couldn't find reliable public data, so this field is left blank rather than guessed.
Completely different pricing structures
Fable 5's output price is nearly 1.7x Sol's ($50 vs $30 per million tokens), and its input price is 2x Sol's ($10 vs $5). Sol's price went untouched in the 2026-07-30 GPT-5.6 family-wide price cut (Terra dropped 20%, Luna dropped 80% in the same round), suggesting OpenAI considers Sol's pricing already competitive enough that it didn't need a cut.
Context windows are close -- not a deciding factor
Fable 5 sits around 1,000,000 tokens, Sol around 1,050,000 -- essentially tied on the long-context dimension. That's not where the real choice lies; pricing structure and how much you trust the 80.3% figure matter more.
How to Choose
Guidance by budget sensitivity and task complexity -- not a single "which is stronger" verdict.
Budget-sensitive, high volume: lean Sol
Sol's output price is only 60% of Fable 5's, and its input price is half. If your workflow is high-frequency, high-volume calls -- test generation in CI, bulk code review -- that price gap gets amplified by volume, and Sol's bill advantage becomes significant.
Chasing the benchmark number, budget isn't the constraint: Fable 5
If the absolute SWE-Bench Pro number matters more to you and budget isn't the primary constraint, Fable 5's 80.3% is currently tied for the top of that leaderboard -- provided you accept the caveat about the official evaluation methodology noted above.
Not sure? Run a small side-by-side first
Both models are callable on QCode with the same key, so instead of debating which is "stronger" in the abstract, run a small batch of your own real tasks against both and decide from there -- actual performance on your codebase and task types tells you more than a benchmark number.
Timeline
Key dates for both models over the last two months.
Claude Fable 5 officially launches
Anthropic releases Fable 5 at an official $10.00 input / $50.00 output (per million tokens) price, with a context window of about 1,000,000 tokens.
GPT-5.6 family launches, with Sol as the flagship tier
OpenAI releases the three-tier GPT-5.6 family (Sol/Terra/Luna). Sol is the top tier, priced at $5.00 input / $30.00 output (per million tokens), with a context window of about 1,050,000 tokens.
GPT-5.6 family-wide price cut, Sol unchanged
Terra dropped 20%, Luna dropped 80% -- Sol's price stayed exactly where it was, the only tier untouched in this round of cuts.
Primary Sources
Anthropic's official Fable 5 launch page; vellum.ai's breakdown of SWE-Bench Pro scoring methodology; LiteLLM model_prices_and_context_window.json (the authoritative source for pricing data, verified 2026-08-08).
FAQ
What's Sol's SWE-Bench Pro score?
OpenAI hasn't separately published a SWE-Bench Pro score for GPT-5.6 Sol, and we couldn't find reliable public data for it. This page leaves that field blank rather than substituting or estimating a number from another leaderboard.
Can Fable 5's 80.3% be directly compared against other models?
Treat it with caution. That score comes from Anthropic's own evaluation scaffolding, not a neutral third-party reproduction, and independent evaluators report different results. The full methodology breakdown is in our dedicated piece, "SWE-Bench Pro: How Fable 5's Score Was Actually Calculated."
Roughly how much would a mid-complexity PR cost on each model?
This is an estimate only, not measured usage data: assuming a mid-complexity PR consumes about 150K input tokens and 20K output tokens, Fable 5 would run about $1.5 (input) + $1.0 (output) = roughly $2.5; Sol would run about $0.75 (input) + $0.6 (output) = roughly $1.35. Actual consumption varies a lot with codebase size, context length, and task complexity -- recalculate with your own real workload.
Can I use both models on QCode?
Yes, both Claude Fable 5 and GPT-5.6 Sol are currently in QCode's callable model list, switchable with the same key -- no separate activation needed.
Create a QCode account
Plans from ¥60 / $8.57. One key across Claude, GPT, and Gemini models.
Related Guides
Claude Fable 5 Complete Pricing Guide
Input/output pricing, cache pricing, and billing details
SWE-Bench Pro: How Fable 5's Score Was Actually Calculated
Breaking down the 80.3% methodology against independent reproductions
GPT-5.6 Sol vs Terra vs Luna: How to Choose
Positioning and selection guidance across the GPT-5.6 tiers
This site is not affiliated with Anthropic or OpenAI. Pricing and benchmark data follow official and authoritative third-party sources; information on this page is current as of 2026-08-08 and may change. Cost estimates are for reference only and do not represent measured usage data.