Model comparison
GPT-6 Astra vs Upstage Solar Pro 4
OpenAI against Upstage, compared on context, price, and verified benchmark results.
Catalog record checked September 5, 2026Individual provider fields may changeEvidence confidence: High — see receipts below
OpenAI
GPT-6 Astra
Frontier
Upstage
Upstage Solar Pro 4
Frontier
| Specification | GPT-6 Astra | Upstage Solar Pro 4 |
|---|---|---|
| Provider | OpenAI | Upstage |
| Tier | Frontier | Frontier |
| Context window | Winner: 1.05M | 524K |
| Max output | 128K | Not verifiedUnverified |
| Input / 1M tokens | $10 | Winner: $0.30 |
| Output / 1M tokens | $50 | Winner: $1.20 |
| Weights | Closed | Closed |
| Parameters | computer-use flagship | Not disclosedUnverified |
| Reasoning levels | low, medium, high, xhigh, max | low, medium, high |
| Modalities | text, image | text |
| API model id | gpt-6-astra | solar-pro-4 |
| Released | September 3, 2026 | August 10, 2026 |
| Artificial Analysis Intelligence Index [max] (2026-09-03) | 61.2 | Not verifiedUnverified |
| Artificial Analysis Intelligence Index (2026-08-14) | Not verifiedUnverified | 50 |
| DeepSWE 1.1 (2026-09-03) | 74.1 | Not verifiedUnverified |
| OSWorld 2.0 (offline) (2026-09-03) | 72.6 | Not verifiedUnverified |
| GPQA Diamond (2026-09-03) | 96 | Not verifiedUnverified |
| Humanity's Last Exam (2026-09-03) | 57.2 | Not verifiedUnverified |
| Terminal-Bench 2.1 (2026-09-05) | 89.9 | Not 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
- 2026-09-05: Artificial Analysis Terminal-Bench v2.1 (independent, Terminus 2 harness — conflicts with tbench.ai 87.4; harness difference preserved)Agentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-09-03: Terminal-Bench official leaderboard (independent, native harness, high effort; captured 2026-09-03 — the live board has since moved to Terminal-Bench 4.0)Agentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-09-03: OpenAI GPT-6 Astra launch chart (vendor, with tools; transcribed by Vellum)Agentic software engineering: pass@1 on real repo tasks with reported cost per completed task. Comparability: directly comparable
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
Pricing tiers: GPT-6 Astra: Standard $10/$50 per MTok (≤272K context); >272K input billed $20/$75 (Fast mode output $100). Cached input $1/MTok; Fast mode is 2x price for ~2.5x speed. Knowledge cutoff Apr 30 2026. Rolling out over several days from 2026-09-03; Enterprise tenants get it disabled by default. · Upstage Solar Pro 4: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
GPT-6 Astra
GPT-6 Astra is OpenAI's computer-use flagship — the first model it gates at the Preparedness Framework's 'Critical' cybersecurity threshold, trained on >100,000 GPUs at Stargate.
Best for
- Computer-use agents
- Agentic coding
- Hard reasoning
Watch out
Gated at the 'Critical' cyber threshold and disabled by default for Enterprise; long-context work bills $20/$75 above 272K input tokens.
Upstage Solar Pro 4
Solar Pro 4 is Upstage's closed flagship with a 524K context at a low launch price.
Best for
- Long-context
- Cost-sensitive API
- Korean + English
Watch out
Closed API; promo pricing may end.
When the cheaper one wins
Upstage Solar Pro 4 is cheaper on output at $1.20 per million tokens against $50 for GPT-6 Astra — about 42×. 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 pickerEvidence 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.
- 3/5 core specs verified on both sides — Not published for at least one side: max output, 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 6 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.
- GPT-6 Astra: OpenAI — Introducing GPT-6 Astra (accessed 2026-09-03)
- GPT-6 Astra: OpenAI API pricing (gpt-6-astra $10/$50) (accessed 2026-09-03)
- GPT-6 Astra: CNBC — OpenAI launches GPT-6 Astra (accessed 2026-09-03)
- GPT-6 Astra: OpenAI model docs — gpt-6-astra (128K max output, effort levels) (accessed 2026-09-05)
- Upstage Solar Pro 4: Upstage — Solar Pro 4 (accessed 2026-08-29)
- Upstage Solar Pro 4: Upstage (accessed 2026-08-29)
Related comparisons
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- Claude Fable 5 vs Upstage Solar Pro 4
- Claude Mythos 5.1 vs GPT-6 Astra
- Claude Mythos 5.1 vs Upstage Solar Pro 4
Diving deeper on one model? GPT-6 Astra · Upstage Solar Pro 4
Common questions
GPT-6 Astra vs Upstage Solar Pro 4
Answered from the verified figures on this page rather than general guidance.
Is GPT-6 Astra or Upstage Solar Pro 4 cheaper for input?
Upstage Solar Pro 4 is cheaper at $0.30 per million input tokens, against $10 for GPT-6 Astra — roughly 33× 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-6 Astra has tiered pricing: Standard $10/$50 per MTok (≤272K context); >272K input billed $20/$75 (Fast mode output $100). Cached input $1/MTok; Fast mode is 2x price for ~2.5x speed. Knowledge cutoff Apr 30 2026. Rolling out over several days from 2026-09-03; Enterprise tenants get it disabled by default. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
Is GPT-6 Astra or Upstage Solar Pro 4 cheaper for output?
Upstage Solar Pro 4 is cheaper at $1.20 per million output tokens, against $50 for GPT-6 Astra — roughly 42× 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-6 Astra has tiered pricing: Standard $10/$50 per MTok (≤272K context); >272K input billed $20/$75 (Fast mode output $100). Cached input $1/MTok; Fast mode is 2x price for ~2.5x speed. Knowledge cutoff Apr 30 2026. Rolling out over several days from 2026-09-03; Enterprise tenants get it disabled by default. Upstage Solar Pro 4 has tiered pricing: List $0.30/$1.20 per MTok; live promo rate is $0.03/$0.12 (90% off through 2026-09-10). Closed API. 524K context.
Which has the larger context window, GPT-6 Astra or Upstage Solar Pro 4?
GPT-6 Astra accepts 1.05M tokens against 524K for Upstage Solar Pro 4. This only matters if you routinely send very long documents or large codebases.
Do GPT-6 Astra and Upstage Solar Pro 4 support the same reasoning levels?
GPT-6 Astra exposes low, medium, high, xhigh, max, while Upstage Solar Pro 4 exposes low, medium, high.
Should I use GPT-6 Astra or Upstage Solar Pro 4?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. GPT-6 Astra suits computer-use agents; Upstage Solar Pro 4 suits long-context.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: Upstage Solar Pro 4 costs $0.30 per 1M tokens versus $10 for GPT-6 Astra — a 33.3x difference at the headline tier.
- Context: GPT-6 Astra takes 1.05M against 524K for Upstage Solar Pro 4 — only decisive if your prompts approach the smaller window.
- Measured capability: GPT-6 Astra leads Artificial Analysis Intelligence Index 61.2 to 50 (measured 2026-09-03).
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.