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Claude Opus 4.5 vs Seed 2.1 Pro Preview

Anthropic · released

Wins 0 of 4 areas

—

ByteDance

Wins 4 of 4 areas

Coding · Agents · Reasoning · Images and charts

Seed 2.1 Pro Preview is the stronger all-rounder.

Scores updated · 21 tests both models report · How we compare

Where each one wins

Tests won in each of the four areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.

What it costs

Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.

Claude Opus 4.5$5.00 to read · $25.00 to write$30Price from Anthropic's own price page
Seed 2.1 Pro PreviewNo current price is tracked.

The biggest differences

The tests each model wins by the widest margin, up to three each. Scores are out of 100.

Where Seed 2.1 Pro Preview pulls ahead

  • Finds hard-to-locate facts by browsing the webBrowseComp+49.2points aheadSeed 2.1 Pro Preview86.2Claude Opus 4.537
  • Real work tasks from 44 professionsGDPVal+40.6points aheadSeed 2.1 Pro Preview87.9Claude Opus 4.547.3
  • Very hard expert questions across many subjectsHumanity's Last Exam+25.6points aheadSeed 2.1 Pro Preview55.7Claude Opus 4.530.1

Where Claude Opus 4.5 pulls ahead

No clear win on a test scored out of 100.

Every test, side by side

All 21 tests both models report. The winning score is in its model's colour; marks a score checked independently.

CodingSeed 2.1 Pro Preview

Full coding ranking

AgentsSeed 2.1 Pro Preview

Full agents ranking

ReasoningSeed 2.1 Pro Preview

Full reasoning ranking

Images and chartsSeed 2.1 Pro Preview
  • CharXiv (RQ)Seed 2.1 Pro Preview by 19.267.286.4+19.2
  • MathVistaSeed 2.1 Pro Preview by 10.580.290.7+10.5
  • MMMU-ProSeed 2.1 Pro Preview by 8.77482.7+8.7

Full images and charts ranking

Other results9 tests, not counted

Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.

Questions people ask

Which is better, Claude Opus 4.5 or Seed 2.1 Pro Preview?

Seed 2.1 Pro Preview wins all four areas where both have results: coding, agents, reasoning and images and charts. Claude Opus 4.5 wins none.

Which is better for coding?

Seed 2.1 Pro Preview. It wins 3 of the 3 coding tests both models report; Claude Opus 4.5 wins none.

How do you compare the two?

We use the 21 benchmark tests both models have published scores on. The verdict counts the 12 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 9 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.

Compare Claude Opus 4.5 with

Anthropic

Across the field

Compare Seed 2.1 Pro Preview with

ByteDance

Across the field

All comparisons