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Model comparison - Open weights vs closed

Claude Opus 5.5 vs DeepSeek V4 Pro

Claude Opus 5.5 is from Anthropic and DeepSeek V4 Pro is from DeepSeek. On list price, Claude Opus 5.5 charges 3x DeepSeek V4 Pro's input price ($4 vs $1.32 per 1M tokens), and Claude Opus 5.5 charges 5.1x DeepSeek V4 Pro's output price ($20 vs $3.96 per 1M tokens). Claude Opus 5.5 and DeepSeek V4 Pro both have a 1,000,000-token context window; max output is 128,000 and 393,216 tokens per response. Claude Opus 5.5 was released on September 22, 2026 and DeepSeek V4 Pro on April 24, 2026. DeepSeek V4 Pro publishes open weights (MIT); Claude Opus 5.5 is closed-weights.

Last verified from each provider's pricing page. All sources

Anthropic - Closed

Claude Opus 5.5
Input / 1M
$4
Output / 1M
$20
Context
1M

DeepSeek - Open

DeepSeek V4 Pro
Input / 1M
$1.32
Output / 1M
$3.96
Context
1M

Side-by-side specs

SpecClaude Opus 5.5DeepSeek V4 Pro
ProviderAnthropicDeepSeek
Input / 1M tokens$4$1.32
Output / 1M tokens$20$3.96
Cache read / 1M$0.20$0.044
Cache write / 1M$5-
Batch input / 1M$2-
Batch output / 1M$10-
Context window1,000,0001,000,000
Max output128,000393,216
Release date
WeightsClosedOpen
License-MIT
API model idclaude-opus-5-5deepseek-v4-pro
AI Gateway idanthropic/claude-opus-5.5deepseek/deepseek-v4-pro
Last verified

Prices in USD per 1M tokens at each provider's standard first-party rate. A dash means the provider does not bill that item separately or no primary page states it.

What each costs in practice

The same three workloads every model page uses, worked from each model's standard list rates. Swap in your own token counts with the math on each model's page.

WorkloadClaude Opus 5.5DeepSeek V4 Pro
One agent session1M input tokens and 100K output tokens, no caching.$6.00$1.72
A chat app10,000 requests a day at 2K input and 500 output tokens each.$180.00$5,400.00 per 30-day month$46.20$1,386.00 per 30-day month
The same session at a 90% cache hit90% of the input is read from the prompt cache. The one-time cache write premium is not included.$2.58$0.5676
Show the math

Claude Opus 5.5

  • One agent sessionInput: 1M x $4 = $4.00Output: 0.1M x $20 = $2.00
  • A chat appInput: 20M x $4 = $80.00Output: 5M x $20 = $100.00
  • The same session at a 90% cache hitCached input: 0.9M x $0.20 = $0.18Uncached input: 0.1M x $4 = $0.40Output: 0.1M x $20 = $2.00

DeepSeek V4 Pro

  • One agent sessionInput: 1M x $1.32 = $1.32Output: 0.1M x $3.96 = $0.396
  • A chat appInput: 20M x $1.32 = $26.40Output: 5M x $3.96 = $19.80
  • The same session at a 90% cache hitCached input: 0.9M x $0.044 = $0.0396Uncached input: 0.1M x $1.32 = $0.132Output: 0.1M x $3.96 = $0.396

Benchmarks under the same setting

No board in the benchmark directory lists both Claude Opus 5.5 and DeepSeek V4 Pro under the same setting, so there is no like-for-like score to show here.

Set them up in your tools

Step-by-step guides whose official docs list Claude Opus 5.5 or DeepSeek V4 Pro by model id.

Model pages

FAQ

How do Claude Opus 5.5 and DeepSeek V4 Pro compare on price?

On list price, Claude Opus 5.5 charges 3x DeepSeek V4 Pro's input price ($4 vs $1.32 per 1M tokens), and Claude Opus 5.5 charges 5.1x DeepSeek V4 Pro's output price ($20 vs $3.96 per 1M tokens). For one agent session of 1M input and 100K output tokens with no caching, that is $6.00 on Claude Opus 5.5 and $1.72 on DeepSeek V4 Pro. Prices are each provider's first-party list rates, verified October 17, 2026 and October 17, 2026.

What are the context windows of Claude Opus 5.5 and DeepSeek V4 Pro?

Claude Opus 5.5 and DeepSeek V4 Pro both have a 1,000,000-token context window; max output is 128,000 and 393,216 tokens per response.

Are Claude Opus 5.5 and DeepSeek V4 Pro open weights?

Claude Opus 5.5 is closed-weights and is called through Anthropic's API as claude-opus-5-5. DeepSeek V4 Pro's weights are published at huggingface.co under the MIT.

More comparisons

Sources

Claude Opus 5.5 verified from platform.claude.com; DeepSeek V4 Pro verified from api-docs.deepseek.com. This page is as current as the older of the two: .

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