> GPT-6.1 Sol vs Step 5 Preview: index scores 184 and ~175 (GPT-4 = 100), API prices, context windows and results on the same independent tests, side by side.

Up to four models

# Compare

Side by side on the same independent tests, with price and context. The link in your address bar shares this exact comparison.

[GPT-6.1 Sol](https://themodelindex.org/models/gpt-6-1-sol/)

[Step 5 Preview](https://themodelindex.org/models/step-5-preview/)

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Next to GPT-6.1 Sol

Cheapest at this level

Claude Sonnet 5.5

Best open model, measured

Kimi K3

Closest rival, another lab

Gemini 4 Argon

The version it replaced

GPT-6 Sol

Where it started

GPT-4

Presets

Best open vs best closed (measured)

Today vs GPT-4 (2023)

Top three labs

US vs China, best of each

[GPT-6.1 Sol](https://themodelindex.org/models/gpt-6-1-sol/)

184

168–200

Weights

Closed

Released

Sep 2026

Price in / out

$2.0 / $10

Context

1.05M

Core tests taken

3 of 8

[Step 5 Preview](https://themodelindex.org/models/step-5-preview/)

~175

estimated

Weights

Closed

Released

Sep 2026

Price in / out

–

Context

–

Core tests taken

–

GPT-6.1 Sol and Step 5 Preview are too close to call (9 points apart, within the uncertainty) (one score is an estimate).

## Test by test · independent results · Epoch AI

GPT-6.1 Sol

Step 5 Preview

These models share no independent tests yet.

Only tests that at least two of these models have taken. Bold rows are the core tests shown on every profile; all of these results inform the index score. Task length (METR) is listed below the chart because it is a duration, not a percentage.

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Source: https://themodelindex.org/compare/gpt-6-1-sol-vs-step-5-preview/ · The Model Index · data as of 2026-10-01