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Claude Opus 5.5 vs GPT-6 Astra: API Cost Comparison

Frontier-quality options for hard coding and agent work. Astra is OpenAI's flagship; Opus 5.5 sits below Anthropic's top tier on price.

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  • Updated 7 Nov 2026
Claude Opus 5.5 and GPT-6 Astra pricing side by side
Side by sideClaude Opus 5.5
Anthropic
GPT-6 Astra
OpenAI
Input / 1M$4$10
Output / 1M$20$50
Cached input / 1M$0.20$1
Batch discount50% off50% off
Context window1M tokens1.05M tokens
Long-prompt surchargeNoneAbove 272K input
TierFrontierFrontier

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
$4,200
Claude Opus 5.5
Priciest
$10,500
GPT-6 Astra
Spread
2.5×
priciest vs cheapest
Per 1K users / mo
Claude Opus 5.5Cheapest
$4,200$2,100
GPT-6 Astra
$10,500$5,250
Per 1K users assumesrequests per user per day.

Where the money is

If 60% of your traffic is simple enough for Claude Opus 5.5, routing it there instead of GPT-6 Astra saves about $3,780/month.

Caching half your input on GPT-6 Astra (a shared system prompt or document) would cut about $2,700/month.

You're looking at $4,200–$10,500/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 Opus 5.5 vs GPT-6 Astra
Requests / dayClaude Opus 5.5GPT-6 AstraDifference
1,000$420$1,050$630
10,000$4,200$10,500$6,300
100,000$42,000$105,000$63,000

By request type:

Cost per 1,000 calls by request type, Claude Opus 5.5 vs GPT-6 Astra
Per 1K callsClaude Opus 5.5GPT-6 Astra
Classification or routing call$1.80$4.50
Support chat reply$11.00$27.50
RAG answer over your docs$32.00$80.00
Long document summary$180$450
02

When to pick which

  • Claude Opus 5.5 is 2.5× cheaper on input tokens, which matters most for RAG and long prompts.
  • Claude Opus 5.5 is 2.5× cheaper on output tokens, which matters most for long answers, code generation and reasoning.
  • Cache reads are 5.0× cheaper on Claude Opus 5.5 ($0.20 vs $1 per 1M), so it pulls ahead when your prompts share a long fixed prefix.
  • Both offer 50% off for batch processing.
  • GPT-6 Astra has the larger context window (1.05M tokens vs 1M tokens).
  • GPT-6 Astra bills the whole request at a higher rate once input passes 272,000 tokens.

Claude Opus 5.5: Complex coding, multi-step agents and analysis where you need frontier quality at well under top-tier prices.

GPT-6 Astra: OpenAI's flagship for complex reasoning and coding, when quality matters more than cost.

03

Verdict

Claude Opus 5.5 wins on price

2.5× cheaper

On price alone, Claude Opus 5.5 wins: about 2.5× cheaper than GPT-6 Astra 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 Opus 5.5 or GPT-6 Astra?
For a typical request of 2,000 input and 300 output tokens, Claude Opus 5.5 is about 2.5× cheaper: $0.0140 per call on Claude Opus 5.5 vs $0.0350 on GPT-6 Astra. At 10,000 requests a day that is $4,200 vs $10,500 a month.
Can I use both Claude Opus 5.5 and GPT-6 Astra?
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 OpenAI 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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