Skip to main content
AI Choice Engine

Model comparison

GPT-5.5 vs GPT-6 Sol

Two OpenAI tiers compared on the figures that decide which one a workload actually needs.

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

OpenAI

GPT-5.5

Frontier

vs

OpenAI

GPT-6 Sol

Balanced

AI model capability comparison
SpecificationGPT-5.5GPT-6 Sol
ProviderOpenAIOpenAI
TierFrontierBalanced
Context window1.05M1.05M
Max output128K128K
Input / 1M tokens$5Winner: $2
Output / 1M tokens$30Winner: $10
WeightsClosedClosed
ParametersNot disclosedUnverifiedGPT-6 mid-price tier
Reasoning levelsnone, low, medium, high, xhighnone, low, medium, high, xhigh, max
Modalitiestext, imagetext, image
API model idgpt-5.5gpt-6-sol
ReleasedApril 23, 2026September 22, 2026
Artificial Analysis Intelligence Index [xhigh] (2026-09-26)38.4Not verifiedUnverified
Artificial Analysis Intelligence Index [max] (2026-09-26)Not verifiedUnverified47.5
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
DeepSWE 1.1 [max] (2026-09-22)Not verifiedUnverified68.8
OSWorld 2.0 (offline) [xhigh] (2026-09-22)Not verifiedUnverified60.5
Terminal-Bench 4.0 [max] (2026-09-26)Not verifiedUnverified43.9

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.

GPT-6 Sol: Replaces GPT-5.6 Sol at 50% of its $4/$20 promo price. Cached input $0.20/MTok; cache writes $2.50 (1.25x). Above 272K input the whole request bills $4/$15 ($0.40 cached). Batch/Flex $1/$5; Fast mode $4/$20. Knowledge cutoff Apr 20 2026. Launched in the API, ChatGPT Work and Codex the same day.

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Superseded by GPT-5.6 and then GPT-6 Astra/Sol; still served and widely integrated.

BalancedRecord checked September 26, 2026

GPT-6 Sol

GPT-6 Sol brings GPT-6 Astra's training advances to OpenAI's mid-priced tier — OpenAI claims roughly half GPT-5.6 Sol's factual-error rate at half its price, with a 1.05M-token context.

Best for

  • Default OpenAI production model
  • Agentic coding
  • Long-context knowledge work

Watch out

Brand-new (2026-09-22): the DeepSWE figure is vendor-reported and it is not yet on the independent boards; long prompts above 272K bill $4/$15 for the whole request.

When the cheaper one wins

GPT-6 Sol is cheaper on output at $10 per million tokens against $30 for GPT-5.5 — about 3.0×. 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. These are standard-tier API rates, excluding batch and cache discounts.

Run the model picker

Evidence confidence: High

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.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
  • 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 · GPT-6 Sol

Common questions

GPT-5.5 vs GPT-6 Sol

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

Is GPT-5.5 or GPT-6 Sol cheaper for input?
GPT-6 Sol is cheaper at $2 per million input tokens, against $5 for GPT-5.5 — roughly 2.5× 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. GPT-6 Sol has tiered pricing: Replaces GPT-5.6 Sol at 50% of its $4/$20 promo price. Cached input $0.20/MTok; cache writes $2.50 (1.25x). Above 272K input the whole request bills $4/$15 ($0.40 cached). Batch/Flex $1/$5; Fast mode $4/$20. Knowledge cutoff Apr 20 2026. Launched in the API, ChatGPT Work and Codex the same day.
Is GPT-5.5 or GPT-6 Sol cheaper for output?
GPT-6 Sol is cheaper at $10 per million output tokens, against $30 for GPT-5.5 — roughly 3.0× 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. GPT-6 Sol has tiered pricing: Replaces GPT-5.6 Sol at 50% of its $4/$20 promo price. Cached input $0.20/MTok; cache writes $2.50 (1.25x). Above 272K input the whole request bills $4/$15 ($0.40 cached). Batch/Flex $1/$5; Fast mode $4/$20. Knowledge cutoff Apr 20 2026. Launched in the API, ChatGPT Work and Codex the same day.
Which has the larger context window, GPT-5.5 or GPT-6 Sol?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do GPT-5.5 and GPT-6 Sol support the same reasoning levels?
GPT-5.5 exposes none, low, medium, high, xhigh, while GPT-6 Sol exposes none, low, medium, high, xhigh, max.
Should I use GPT-5.5 or GPT-6 Sol?
GPT-5.5 is the frontier tier and GPT-6 Sol the balanced tier. The useful question is whether your hardest task actually fails on the cheaper one — most production volume such as classification, extraction and summarisation does not.

Next step

Choosing between them

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

  • Input price: GPT-6 Sol costs $2 per 1M tokens versus $5 for GPT-5.5 — a 2.5x difference at the headline tier.
  • Measured capability: GPT-6 Sol leads Artificial Analysis Intelligence Index 47.5 to 38.4 (measured 2026-09-26).
  • Positioning: GPT-5.5 sits in the frontier tier, GPT-6 Sol in the balanced tier — most production volume (classification, extraction, summarisation) does not need the pricier tier.
Run the model pickerEstimate stack costAll model comparisons

Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.