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AI Choice Engine

Model comparison

GPT-5.5 vs Muse Spark 1.2

OpenAI against Meta, compared on context, price, and verified benchmark results.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

OpenAI

GPT-5.5

Frontier

vs

Meta

Muse Spark 1.2

Frontier

AI model capability comparison
SpecificationGPT-5.5Muse Spark 1.2
ProviderOpenAIMeta
TierFrontierFrontier
Context windowWinner: 1.05M1.05M
Max output128KNot verifiedUnverified
Input / 1M tokens$5Winner: $1.25
Output / 1M tokens$30Winner: $4.25
WeightsClosedClosed
ParametersNot disclosedUnverifiedMeta frontier model
Reasoning levelsnone, low, medium, high, xhighminimal, low, medium, high, xhigh, max
Modalitiestext, imagetext, image, video, audio, pdf
API model idgpt-5.5muse-spark-1.2
ReleasedApril 23, 2026August 5, 2026
Artificial Analysis Intelligence Index [xhigh] (2026-09-26)38.4Winner: 39.6
SWE-bench Verified (2026-09-01)82.6Not verifiedUnverified
Terminal-Bench 2.1 (2026-07-27)83.4Not verifiedUnverified
GPQA Diamond (2026-07-27)93.5Not verifiedUnverified
Humanity's Last Exam (2026-04-23)52.2Not verifiedUnverified

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

Pricing tiers

GPT-5.5: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.

Muse Spark 1.2: $1.25/$4.25 per MTok on Meta's Model API (Standard tier shared with Muse Spark 1.3; cached input $0.15). Closed weights.

FrontierRecord checked September 26, 2026

GPT-5.5

GPT-5.5 is OpenAI's April 2026 flagship, now two generations back — strong on Terminal-Bench 2.0 (82.7%) with a 1.05M-token context.

Best for

  • Reasoning
  • Agentic coding
  • Long-context work

Watch out

Superseded by GPT-5.6 and then GPT-6 Astra/Sol; still served and widely integrated.

FrontierRecord checked September 26, 2026

Muse Spark 1.2

Muse Spark 1.2 is Meta's closed frontier model until the 1.3 refresh (2026-09-02) — still served and ranked in the LMArena text top 10 as of mid-2026.

Best for

  • Frontier reasoning
  • Meta ecosystem
  • Agentic work

Watch out

Closed-weights (unlike Llama 4); Meta's post-Llama-4 frontier branding.

When the cheaper one wins

Muse Spark 1.2 is cheaper on output at $4.25 per million tokens against $30 for GPT-5.5 — about 7.1×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. On DeepSWE 1.1, Muse Spark 1.2 is 54.9% Pass@1 at $3.7/task versus GPT-5.5 at 67% / $7.23/task. These are standard-tier API rates, excluding batch and cache discounts.

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Evidence confidence: Medium

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 3/5 core specs verified on both sides — Not published for at least one side: max output, parameter count.
  • 1 shared named benchmark (scores match) — Measured on: Artificial Analysis Intelligence Index — scores are equivalent, so the benchmark does not separate the pair.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? GPT-5.5 · Muse Spark 1.2

Common questions

GPT-5.5 vs Muse Spark 1.2

Answered from the verified figures on this page rather than general guidance.

Is GPT-5.5 or Muse Spark 1.2 cheaper for input?
Muse Spark 1.2 is cheaper at $1.25 per million input tokens, against $5 for GPT-5.5 — roughly 4.0× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. Muse Spark 1.2 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (Standard tier shared with Muse Spark 1.3; cached input $0.15). Closed weights.
Is GPT-5.5 or Muse Spark 1.2 cheaper for output?
Muse Spark 1.2 is cheaper at $4.25 per million output tokens, against $30 for GPT-5.5 — roughly 7.1× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; GPT-5.5 has tiered pricing: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15. Muse Spark 1.2 has tiered pricing: $1.25/$4.25 per MTok on Meta's Model API (Standard tier shared with Muse Spark 1.3; cached input $0.15). Closed weights.
Which has the larger context window, GPT-5.5 or Muse Spark 1.2?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do GPT-5.5 and Muse Spark 1.2 support the same reasoning levels?
GPT-5.5 exposes none, low, medium, high, xhigh, while Muse Spark 1.2 exposes minimal, low, medium, high, xhigh, max.
Should I use GPT-5.5 or Muse Spark 1.2?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. GPT-5.5 suits reasoning; Muse Spark 1.2 suits frontier reasoning.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: Muse Spark 1.2 costs $1.25 per 1M tokens versus $5 for GPT-5.5 — a 4x difference at the headline tier.
  • Context: GPT-5.5 takes 1.05M against 1.05M for Muse Spark 1.2 — only decisive if your prompts approach the smaller window.
  • Measured capability: Muse Spark 1.2 leads Artificial Analysis Intelligence Index 39.6 to 38.4 (measured 2026-09-26).
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