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Claude Fable 5 vs Step 5 Preview

Claude Fable 5 grades higher overall (90.7 against 75.2). Step 5 Preview costs 93% less for the same work.

Claude Fable 5

by Anthropic · #3 of 67 overall

Coming soon · price at launch
Context
1M
Input / 1M
$10.00
Output / 1M
$50.00

Step 5 Preview

by StepFun · #24 of 67 overall

Coming soon · price at launch
Context
1M
Input / 1M
$1.00
Output / 1M
$2.70

Better overall

Claude Fable 5

Grade 90.7 vs 75.2

Cheaper

Step 5 Preview

93% less, $1.43 vs $20.00 blended

Larger context

Step 5 Preview

1M vs 1M tokens

Head to head

Public benchmarks. Longer is better; each value links to its source.

LMArena TextElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
Claude Fable 5Claude Fable 5: 1,503
Step 5 PreviewStep 5 Preview: 1,448
LMArena WebDevElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
Claude Fable 5Claude Fable 5: 1,624
Step 5 PreviewStep 5 Preview: 1,564
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
Claude Fable 5Claude Fable 5: 1,551
Step 5 PreviewStep 5 Preview: 1,506
SWE-bench Verified% of issues resolved · SWE-bench · Jun 9, 2026 · reference
Claude Fable 5Claude Fable 5: 95%v
Step 5 PreviewStep 5 Preview: —
SWE-Bench Pro% of tasks resolved · Scale AI SWE-Bench Pro · Jun 9, 2026 · reference
Claude Fable 5Claude Fable 5: 80%v
Step 5 PreviewStep 5 Preview: —
Terminal-Bench 4.0% of tasks passed · Terminal-Bench · Sep 20, 2026 · reference
Claude Fable 5Claude Fable 5: —
Terminal-Bench 2.1% of tasks passed · Terminal-Bench · Jun 9, 2026 · reference
Step 5 PreviewStep 5 Preview: —

Claude Fable 5Step 5 Previewv = reported by the model’s maker. — = no public score yet. Arena bars span the range across every model we grade.

What it costs you

Drag to match your monthly usage.

Claude Fable 5$4,000 /month
Step 5 Preview$308 /month

Step 5 Preview saves you $3,692 a month at this usage, $44,304 a year.

At a glance

AttributeClaude Fable 5Step 5 Preview
Made byAnthropicStepFun
AvailabilityComing soonComing soon
Overall gradeExcellent · 90.7Excellent · 75.2
Overall rank#3 of 67#24 of 67
Input price$10.00 per 1M$1.00 per 1M
Output price$50.00 per 1M$2.70 per 1M
Context window1,000,000 tokens1,048,576 tokens
Reasoning levelsYesNo
Reads imagesYesYes
Model IDclaude-fable-5step-5-preview

Try both with one key

Same endpoint, same key, both hosted in the USA. Change one word to switch models, in Claude Code, Cursor, Cline or your own code.

Get your API key
# Ask either model the same thing
curl https://fullsendai.com/v1/chat/completions \
  -H "Authorization: Bearer $FULLSEND_API_KEY" \
  -d '{"model": "claude-fable-5", "messages": [...]}'

# …then swap one word
  -d '{"model": "step-5-preview", "messages": [...]}'

Questions

Is Claude Fable 5 or Step 5 Preview better?

Claude Fable 5 grades 90.7 against 75.2 for Step 5 Preview, from public benchmarks.

Which is cheaper, Claude Fable 5 or Step 5 Preview?

Step 5 Preview: $1.00 in and $2.70 out per million tokens, against $10.00 and $50.00 through FullsendAI.

Which has the larger context window?

Step 5 Preview, with 1,048,576 tokens.

Can I use both with one API key?

Yes, once they launch: both are coming soon, at the prices shown, and both will use the same FullsendAI key.

Model rankingsAll benchmarksCompare other models

Scores: LMArena (CC BY 4.0), SWE-bench, Scale AI SWE-Bench Pro, Terminal-Bench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.