Is GPT-5.5 or GPT-5 Nano cheaper?

For a typical request (10,000 input + 2,000 output tokens), GPT-5 Nano is cheaper — about 99% less, or roughly $10870 saved per 100,000 requests. GPT-5.5 runs $5/$30 per 1M input/output tokens; GPT-5 Nano runs $0.05/$0.4.

Which has the larger context window?

GPT-5.5, at 1,050,000 tokens versus 400,000.

How accurate are these token counts?

GPT-5.5: Exact tokenization via the canonical OpenAI vocab (o200k_base). GPT-5 Nano: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.

GPT-5.5 vs GPT-5 Nano: pricing & cost comparison

On input tokens, GPT-5 Nano is the cheaper of the two — 99% less per million ($5 vs $0.05). On output, GPT-5 Nano is 99% cheaper ($30 vs $0.4) — and since output is usually the dominant cost driver, that gap matters more than it looks.

Side by side

	GPT-5.5	GPT-5 Nano
Input / 1M tokens	$5	$0.05
Output / 1M tokens	$30	$0.4
Context window	1,050,000	400,000
Token-count accuracy	exact	exact
Cost — 10,000 input + 2,000 output tokens	$0.11	$0.0013

What a real request costs

Take a representative turn — 10,000 input + 2,000 output tokens. GPT-5.5 comes to $0.11, GPT-5 Nano to $0.0013. Across 100,000 requests that's a $10870 swing in favour of GPT-5 Nano. To run the numbers on your actual prompt, paste it into the calculator and toggle Compare across all models.

Same vendor — an easy switch

Moving between GPT-5.5 and GPT-5 Nano is a same-vendor move — one SDK, one tokenizer, so no recalibration. That makes this a straight cost/quality call: send the routine bulk of traffic to GPT-5 Nano ($0.05/$0.4 per 1M) and reserve GPT-5.5 for the requests that visibly need its extra headroom. On the worked example above that split is worth about 99% per request — small per call, real money once you multiply by volume.

See the full breakdown on the dedicated pages for GPT-5.5 and GPT-5 Nano.

FAQ

Is GPT-5.5 or GPT-5 Nano cheaper?: For a typical request (10,000 input + 2,000 output tokens), GPT-5 Nano is cheaper — about 99% less, or roughly $10870 saved per 100,000 requests. GPT-5.5 runs $5/$30 per 1M input/output tokens; GPT-5 Nano runs $0.05/$0.4.
Which has the larger context window?: GPT-5.5, at 1,050,000 tokens versus 400,000.
How accurate are these token counts?: GPT-5.5: Exact tokenization via the canonical OpenAI vocab (o200k_base). GPT-5 Nano: Exact tokenization via the canonical OpenAI vocab (o200k_base). The dollar math itself is exact once the token count is known.

Both prices are computed from tokenmath's verified pricing table. Rates sourced from developers.openai.com and openai.com, verified 2026-07-06. Vendor pricing changes often — confirm before you commit.