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Claude Sonnet 5.5 vs DeepSeek V4 Pro: API Cost Comparison

A closed mid-tier default against a cheaper open-weight alternative.

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  • Updated 7 Nov 2026
Claude Sonnet 5.5 and DeepSeek V4 Pro pricing side by side
Side by sideClaude Sonnet 5.5
Anthropic
DeepSeek V4 Pro
DeepSeek
Input / 1M$2$1.32
Output / 1M$10$3.96
Cached input / 1M$0.10$0.044
Batch discount50% offNone
Context window1M tokensNot published
Long-prompt surchargeNoneNone
TierMid-tierMid-tier

Workload

tok
tok
%

Repeated system prompt or docs

%

Jobs that can wait hours

Models

Anthropic
OpenAI
Google
Mistral
DeepSeek

$ per 1M tokens, input / output

Monthly cost · 30 days

Cheapest
$1,148
DeepSeek V4 Pro
Priciest
$2,100
Claude Sonnet 5.5
Spread
1.8×
priciest vs cheapest
Per 1K users / mo
DeepSeek V4 ProCheapest
$1,148$574
Claude Sonnet 5.5
$2,100$1,050
Per 1K users assumesrequests per user per day.

Where the money is

If 60% of your traffic is simple enough for DeepSeek V4 Pro, routing it there instead of Claude Sonnet 5.5 saves about $571/month.

Caching half your input on Claude Sonnet 5.5 (a shared system prompt or document) would cut about $570/month.

You're looking at $1,148–$2,100/month.

Most AI products I audit can cut that 30–60% with routing, caching and shorter prompts.

Get a cost-cutting audit
01

Cost at three traffic levels

Same request on both: 2,000 input tokens and 300 output tokens, no caching, no batch, 30-day month.

Monthly cost of Claude Sonnet 5.5 vs DeepSeek V4 Pro
Requests / dayClaude Sonnet 5.5DeepSeek V4 ProDifference
1,000$210$115$95.16
10,000$2,100$1,148$952
100,000$21,000$11,484$9,516

By request type:

Cost per 1,000 calls by request type, Claude Sonnet 5.5 vs DeepSeek V4 Pro
Per 1K callsClaude Sonnet 5.5DeepSeek V4 Pro
Classification or routing call$0.9000$0.5676
Support chat reply$5.50$2.97
RAG answer over your docs$16.00$9.50
Long document summary$90.00$56.76
02

When to pick which

  • DeepSeek V4 Pro is 1.5× cheaper on input tokens, which matters most for RAG and long prompts.
  • DeepSeek V4 Pro is 2.5× cheaper on output tokens, which matters most for long answers, code generation and reasoning.
  • Cache reads are 2.3× cheaper on DeepSeek V4 Pro ($0.044 vs $0.10 per 1M), so it pulls ahead when your prompts share a long fixed prefix.
  • Claude Sonnet 5.5 offers a 50% batch discount for jobs that can wait; DeepSeek V4 Pro has no batch tier.
  • DeepSeek V4 Pro is open-weight, so you can move to self-hosting later without changing models.

Claude Sonnet 5.5: The default for production chat, RAG and coding assistants: strong quality at a mid-tier price.

DeepSeek V4 Pro: DeepSeek's larger open-weight model. A low-cost alternative to mid-tier closed models.

03

Verdict

DeepSeek V4 Pro wins on price

1.8× cheaper

On price alone, DeepSeek V4 Pro wins: about 1.8× cheaper than Claude Sonnet 5.5 for a typical request. Price is one input. Run both on 50 of your real prompts, compare the answers and the billed tokens, and route by difficulty if the quality gap only shows up on hard requests.

04

How the math works

Every provider bills input tokens (your prompt, system prompt and retrieved documents) and output tokens (the reply) separately, per million. Output is usually 4–5× the input price, so chatty apps are output-heavy and RAG apps are input-heavy.

cost per request = (fresh_in × input_price
+ cached_in × cached_price
+ out × output_price) / 1,000,000
× (1 − batched_share × batch_discount)
monthly = cost per request × requests per day × 30

Two adjustments are applied automatically. Introductory prices (currently on some Gemini models) are used until their end date. Long-prompt surcharges kick in when your average input crosses the provider's threshold: 272K tokens on current OpenAI models, 100K on Claude Haiku 5.5.

Not modelled: cache-write premiums, priority or fast tiers, regional surcharges, image and audio tokens, and reasoning tokens a model spends before answering (they bill as output, so add them to your output estimate if you use extended thinking).

05

Questions

Which is cheaper, Claude Sonnet 5.5 or DeepSeek V4 Pro?
For a typical request of 2,000 input and 300 output tokens, DeepSeek V4 Pro is about 1.8× cheaper: $0.00700 per call on Claude Sonnet 5.5 vs $0.00383 on DeepSeek V4 Pro. At 10,000 requests a day that is $2,100 vs $1,148 a month.
Can I use both Claude Sonnet 5.5 and DeepSeek V4 Pro?
Yes, and many teams do. Put a thin routing layer in front of both: send the requests that need the stronger or larger-context model to it, and everything else to the cheaper one. Keep prompts provider-neutral so you can move traffic when prices change.
How often do Anthropic and DeepSeek change prices?
Often enough that a comparison older than a few months is suspect. The prices on this page were verified on 7 Nov 2026 from each provider's own documentation, linked in the Sources section.
06

Sources

All prices are list prices from each provider's own documentation, standard tier, in USD, last verified on 7 Nov 2026. Providers change prices often; if a number here disagrees with the source, the source wins.

07

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Fine print

Tools: on the house.
Engineer: by the hour.

Knowing your AI bill was free. Cutting it in half isn't, but I'm cheaper than the overspend.

I'm Himanshu, an AI and full-stack engineer. I build MVPs, AI agents and the growth plumbing around them for early-stage startups.

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