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Model comparison

GPT-6 Astra vs Step 5 Preview

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

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

OpenAI

GPT-6 Astra

Frontier

vs

StepFun

Step 5 Preview

Frontier

AI model capability comparison
SpecificationGPT-6 AstraStep 5 Preview
ProviderOpenAIStepFun
TierFrontierFrontier
Context windowWinner: 1.05M1M
Max output128KNot verifiedUnverified
Input / 1M tokens$10Winner: $1
Output / 1M tokens$50Winner: $2.70
WeightsClosedClosed
Parametersoverall flagship (reasoning, coding, computer use)600B total / 27B active MoE (StepFun)
Reasoning levelslow, medium, high, xhigh, maxNot verifiedUnverified
Modalitiestext, imagetext, image
API model idgpt-6-astrastep-5-preview
ReleasedSeptember 3, 2026September 18, 2026
Artificial Analysis Intelligence Index [max] (2026-09-26)52.7Not verifiedUnverified
Artificial Analysis Intelligence Index (2026-09-26)Not verifiedUnverified43.7
DeepSWE 1.1 (2026-09-03)74.1Not verifiedUnverified
OSWorld 2.0 (offline) (2026-09-03)72.6Not verifiedUnverified
GPQA Diamond (2026-09-03)96Not verifiedUnverified
Humanity's Last Exam (2026-09-03)57.2Not verifiedUnverified
Terminal-Bench 4.0 [xhigh] (2026-09-26)59.6Not verifiedUnverified
Terminal-Bench 2.1 [xhigh] (2026-09-26)89.1Not 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-6 Astra: Standard $10/$50 per MTok (≤272K input); above 272K input the whole request bills $20/$75. Cached input $1/MTok; cache writes $12.50 (1.25x input). Batch/Flex $5/$25. Fast mode costs 2x for up to 2x the speed ($20/$100 short context, $40/$150 long). Knowledge cutoff Apr 30 2026. Rolled out from 2026-09-03; Enterprise tenants get it disabled by default.

Step 5 Preview: $1.00/$2.70 per MTok on the StepFun platform (cache-hit input $0.05); StepFun lists it under Multimodal Reasoning Models and says output tokens include reasoning. No max-output figure is published. StepFun says open weights follow on 2026-10-15. Release date per Artificial Analysis's listing (StepFun's launch page is undated).

FrontierRecord checked September 26, 2026

GPT-6 Astra

GPT-6 Astra is OpenAI's overall flagship — its most capable model for complex reasoning, coding and computer use, and the first it gates at the Preparedness Framework's 'Critical' cybersecurity threshold.

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. GPT-6 Sol ($2/$10) covers most work at a fifth of the price.

FrontierRecord checked September 26, 2026

Step 5 Preview

Step 5 Preview is StepFun's new frontier reasoning model — a 1M-context, vision-input API preview that lands near Kimi K3 and GLM 5.3 on the Artificial Analysis index at a lower price.

Best for

  • Long-context work on a budget
  • Chinese + English
  • Early testing before the open-weight drop

Watch out

Preview: weights are promised for 2026-10-15 but not yet released, and its max output is unpublished and the launch benchmarks are vendor-run.

Benchmark

DeepSWE 1.1 in context

Only GPT-6 Astra has a published DeepSWE 1.1 result. It is shown against the wider field, with cost per completed task alongside the score.

Local leader

GPT-6 Astra [xhigh]

74%

Rows shown

28

Best published Pass@1 per model (Datacurve's default view)

Snapshot date

2026-09-26

Mirrored from deepswe.datacurve.ai

DeepSWE 1.1 pass@10%16%32%48%64%80%$0$4.50$9.00$13.50$18.00$22.50$27.00Avg cost per taskGPT-6 Astra [xhigh]: 74% · $4.43 · 30k tokens · 29 stepsGemini 3.8 Flash [high]: 74% · $2.36 · 143k tokens · 166 stepsClaude Opus 5 [max]: 74% · $11.84 · 118k tokens · 99 stepsGPT-5.6 Sol [max]: 73% · $8.39 · 60k tokens · 61 stepsClaude Fable 5 [xhigh]: 70% · $13.41 · 80k tokens · 68 stepsGPT-5.6 Terra [max]: 70% · $4.95 · 72k tokens · 76 stepsGLM 5.3 [max]: 69% · $3.99 · 80k tokens · 124 stepsKimi K3 [max]: 69% · $4.65 · 82k tokens · 98 stepsGrok 4.6 [medium]: 68% · $3.45 · 50k tokens · 70 stepsGPT-5.6 Luna [max]: 67% · $3.03 · 73k tokens · 102 stepsGPT-5.5 [xhigh]: 67% · $7.23 · 46k tokens · 82 stepsGemini 3.7 Flash [medium]: 66% · $2.03 · 94k tokens · 117 stepsGLM 5.3 Flash [max]: 63% · $0.48 · 73k tokens · 123 stepsDeepSeek V4-Pro [max]: 63% · $0.24 · 106k tokens · 155 stepsClaude Opus 4.8 [max]: 59% · $13.22 · 135k tokens · 120 stepsQwen3.8-Max [xhigh]: 58% · $3.73 · 95k tokens · 111 stepsMuse Spark 1.2 [xhigh]: 55% · $3.70 · 99k tokens · 101 stepsClaude Sonnet 5 [max]: 54% · $26.40 · 214k tokens · 268 stepsGrok 4.5 [high]: 54% · $2.42 · 36k tokens · 61 stepsDeepSeek V4-Flash [max]: 53% · $0.10 · 108k tokens · 153 stepsMuse Spark 1.1 [xhigh]: 53% · $2.36 · 74k tokens · 96 stepsGPT-5.4 [xhigh]: 52% · $5.65 · 71k tokens · 70 stepsGemini 3.6 Flash [high]: 47% · $4.42 · 96k tokens · 117 stepsGLM 5.2 [max]: 44% · $3.92 · 78k tokens · 129 stepsGemini 3.5 Flash [high]: 36% · $3.45 · 76k tokens · 105 stepsKimi K2.7 Code: 31% · $2.82 · 59k tokens · 149 stepsClaude Sonnet 4.6 [high]: 30% · $5.52 · 76k tokens · 134 stepsGemini 3.1 Pro [high]: 12% · $2.14 · 28k tokens · 76 steps

Better is toward the top-right (higher pass rate, lower cost). X-axis is reversed to match DeepSWE’s public chart. v1.1 uses average cost / tokens / steps; v1 uses published medians.

DeepSWE 1.1 leaderboard with pass rate, cost, tokens, and steps per task
#ModelPass@1Cost / taskTokens / taskSteps / task
1GPT-6 Astra [xhigh]74%$4.4330k29
2Gemini 3.8 Flash [high]74%$2.36143k166
3Claude Opus 5 [max]74%$11.84118k99
4GPT-5.6 Sol [max]73%$8.3960k61
5Claude Fable 5 [xhigh]70%$13.4180k68
6GPT-5.6 Terra [max]70%$4.9572k76
7GLM 5.3 [max]69%$3.9980k124
8Kimi K3 [max]69%$4.6582k98
9Grok 4.6 [medium]68%$3.4550k70
10GPT-5.6 Luna [max]67%$3.0373k102
11GPT-5.5 [xhigh]67%$7.2346k82
12Gemini 3.7 Flash [medium]66%$2.0394k117
13GLM 5.3 Flash [max]63%$0.4873k123
14DeepSeek V4-Pro [max]63%$0.24106k155
15Claude Opus 4.8 [max]59%$13.22135k120
16Qwen3.8-Max [xhigh]58%$3.7395k111
17Muse Spark 1.2 [xhigh]55%$3.7099k101
18Claude Sonnet 5 [max]54%$26.40214k268
19Grok 4.5 [high]54%$2.4236k61
20DeepSeek V4-Flash [max]53%$0.10108k153
21Muse Spark 1.1 [xhigh]53%$2.3674k96
22GPT-5.4 [xhigh]52%$5.6571k70
23Gemini 3.6 Flash [high]47%$4.4296k117
24GLM 5.2 [max]44%$3.9278k129
25Gemini 3.5 Flash [high]36%$3.4576k105
26Kimi K2.7 Code31%$2.8259k149
27Claude Sonnet 4.6 [high]30%$5.5276k134
28Gemini 3.1 Pro [high]12%$2.1428k76

“Best per model” shows each model’s highest published Pass@1, as Datacurve’s own board does; switch to all effort levels to see every configuration. Small gaps may not be statistically meaningful — confirm on deepswe.datacurve.ai.

When the cheaper one wins

Step 5 Preview is cheaper on output at $2.70 per million tokens against $50 for GPT-6 Astra — about 19×. 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.

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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.
  • 3/5 core specs verified on both sides — Not published for at least one side: max output, reasoning levels.
  • 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-6 Astra · Step 5 Preview

Common questions

GPT-6 Astra vs Step 5 Preview

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

Is GPT-6 Astra or Step 5 Preview cheaper for input?
Step 5 Preview is cheaper at $1 per million input tokens, against $10 for GPT-6 Astra — roughly 10× 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 input); above 272K input the whole request bills $20/$75. Cached input $1/MTok; cache writes $12.50 (1.25x input). Batch/Flex $5/$25. Fast mode costs 2x for up to 2x the speed ($20/$100 short context, $40/$150 long). Knowledge cutoff Apr 30 2026. Rolled out from 2026-09-03; Enterprise tenants get it disabled by default. Step 5 Preview has tiered pricing: $1.00/$2.70 per MTok on the StepFun platform (cache-hit input $0.05); StepFun lists it under Multimodal Reasoning Models and says output tokens include reasoning. No max-output figure is published. StepFun says open weights follow on 2026-10-15. Release date per Artificial Analysis's listing (StepFun's launch page is undated).
Is GPT-6 Astra or Step 5 Preview cheaper for output?
Step 5 Preview is cheaper at $2.70 per million output tokens, against $50 for GPT-6 Astra — roughly 19× 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 input); above 272K input the whole request bills $20/$75. Cached input $1/MTok; cache writes $12.50 (1.25x input). Batch/Flex $5/$25. Fast mode costs 2x for up to 2x the speed ($20/$100 short context, $40/$150 long). Knowledge cutoff Apr 30 2026. Rolled out from 2026-09-03; Enterprise tenants get it disabled by default. Step 5 Preview has tiered pricing: $1.00/$2.70 per MTok on the StepFun platform (cache-hit input $0.05); StepFun lists it under Multimodal Reasoning Models and says output tokens include reasoning. No max-output figure is published. StepFun says open weights follow on 2026-10-15. Release date per Artificial Analysis's listing (StepFun's launch page is undated).
Which has the larger context window, GPT-6 Astra or Step 5 Preview?
GPT-6 Astra accepts 1.05M tokens against 1M for Step 5 Preview. This only matters if you routinely send very long documents or large codebases.
Should I use GPT-6 Astra or Step 5 Preview?
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; Step 5 Preview suits long-context work on a budget.

Next step

Choosing between them

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

  • Input price: Step 5 Preview costs $1 per 1M tokens versus $10 for GPT-6 Astra — a 10x difference at the headline tier.
  • Context: GPT-6 Astra takes 1.05M against 1M for Step 5 Preview — only decisive if your prompts approach the smaller window.
  • Measured capability: GPT-6 Astra leads Artificial Analysis Intelligence Index 52.7 to 43.7 (measured 2026-09-26).
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