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DeepSeek V3.1 vs Hy4 Preview

Close to a tie overall. DeepSeek V3.1 costs 66% less for the same work.

DeepSeek V3.1

by DeepSeek · #31 of 67 overall

Coming soon · price at launch
Context
160K
Input / 1M
$0.25
Output / 1M
$0.95

Hy4 Preview

by

Coming soon · price at launch
Context
1M
Input / 1M
$0.83
Output / 1M
$2.50

Better overall

About even

Grade 68.7 vs 69.3

Cheaper

DeepSeek V3.1

66% less, $0.42 vs $1.25 blended

Larger context

Hy4 Preview

160K 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 15, 2026
Hy4 PreviewHy4 Preview: —
LMArena WebDevElo-style rating · LMArena (CC BY 4.0) · Oct 13, 2026
DeepSeek V3.1DeepSeek V3.1: —
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 15, 2026
Hy4 PreviewHy4 Preview: —
Aider Polyglot% of exercises solved · Aider (aider.chat) · Aug 21, 2025
Hy4 PreviewHy4 Preview: —
SWE-bench Verified% of issues resolved · SWE-bench · Aug 21, 2025 · reference
DeepSeek V3.1DeepSeek V3.1: 66%v
Hy4 PreviewHy4 Preview: —
Terminal-Bench 2.1% of tasks passed · Terminal-Bench · Aug 27, 2026 · reference
DeepSeek V3.1DeepSeek V3.1: —
LiveCodeBenchpass@1, % · LiveCodeBench · Aug 21, 2025 · reference
Hy4 PreviewHy4 Preview: —

DeepSeek V3.1Hy4 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.

DeepSeek V3.1$88.00 /month
Hy4 Preview$267 /month

DeepSeek V3.1 saves you $179 a month at this usage, $2,146 a year.

At a glance

AttributeDeepSeek V3.1Hy4 Preview
Made byDeepSeek
AvailabilityComing soonComing soon
Overall gradeStrong · 68.7Not rated
Overall rank#31 of 67Not ranked
Input price$0.25 per 1M$0.83 per 1M
Output price$0.95 per 1M$2.50 per 1M
Context window163,840 tokens1,048,576 tokens
Reasoning levelsYesNo
Reads imagesNoNo
Model IDdeepseek-v3.1hy4-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": "deepseek-v3.1", "messages": [...]}'

# …then swap one word
  -d '{"model": "hy4-preview", "messages": [...]}'

Questions

Is DeepSeek V3.1 or Hy4 Preview better?

They grade within two points of each other (68.7 and 69.3), so pick on price and the benchmarks that match your work.

Which is cheaper, DeepSeek V3.1 or Hy4 Preview?

DeepSeek V3.1: $0.25 in and $0.95 out per million tokens, against $0.83 and $2.50 through FullsendAI.

Which has the larger context window?

Hy4 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), Aider (aider.chat), SWE-bench, Terminal-Bench, LiveCodeBench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.