Is Claude 4.5 Sonnet or GPT-5 cheaper?

For a typical request (10,000 input + 2,000 output tokens), GPT-5 is cheaper — about 46% less, or roughly $2750 saved per 100,000 requests. Claude 4.5 Sonnet runs $3/$15 per 1M input/output tokens; GPT-5 runs $1.25/$10.

Which has the larger context window?

GPT-5, at 400,000 tokens versus 200,000.

How accurate are these token counts?

Claude 4.5 Sonnet: Approximated with cl100k_base — drift typically <2% on English and code. GPT-5: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.

Claude 4.5 Sonnet vs GPT-5: pricing & cost comparison

On input tokens, GPT-5 is the cheaper of the two — 58% less per million ($3 vs $1.25). On output, GPT-5 is 33% cheaper ($15 vs $10) — and since output is usually the dominant cost driver, that gap matters more than it looks.

Side by side

	Claude 4.5 Sonnet	GPT-5
Input / 1M tokens	$3	$1.25
Output / 1M tokens	$15	$10
Context window	200,000	400,000
Token-count accuracy	±2%	exact
Cost — 10,000 input + 2,000 output tokens	$0.06	$0.0325

What a real request costs

Take a representative turn — 10,000 input + 2,000 output tokens. Claude 4.5 Sonnet comes to $0.06, GPT-5 to $0.0325. Across 100,000 requests that's a $2750 swing in favour of GPT-5. To run the numbers on your actual prompt, paste it into the calculator and toggle Compare across all models.

Which should you pick?

These are different vendors, so a switch means a different API and a slightly different tokenizer — budget a small calibration buffer. GPT-5 give exact counts; the others land within a few percent. See the full breakdown on the dedicated pages for Claude 4.5 Sonnet and GPT-5.

FAQ

Is Claude 4.5 Sonnet or GPT-5 cheaper?: For a typical request (10,000 input + 2,000 output tokens), GPT-5 is cheaper — about 46% less, or roughly $2750 saved per 100,000 requests. Claude 4.5 Sonnet runs $3/$15 per 1M input/output tokens; GPT-5 runs $1.25/$10.
Which has the larger context window?: GPT-5, at 400,000 tokens versus 200,000.
How accurate are these token counts?: Claude 4.5 Sonnet: Approximated with cl100k_base — drift typically <2% on English and code. GPT-5: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.