Is Claude 5 Sonnet or Gemini 2.5 Flash cheaper?

For a typical request (10,000 input + 2,000 output tokens), Gemini 2.5 Flash is cheaper — about 80% less, or roughly $3200 saved per 100,000 requests. Claude 5 Sonnet runs $2/$10 per 1M input/output tokens; Gemini 2.5 Flash runs $0.3/$2.5.

Which has the larger context window?

Both support a 1,000,000-token context window.

How accurate are these token counts?

Claude 5 Sonnet: Approximated with cl100k_base — drift typically <2% on English and code. Gemini 2.5 Flash: Approximated with o200k_base; drift typically ~3% on English and code. The dollar math itself is exact once the token count is known.

Claude 5 Sonnet vs Gemini 2.5 Flash: pricing & cost comparison

On input tokens, Gemini 2.5 Flash is the cheaper of the two — 85% less per million ($2 vs $0.3). On output, Gemini 2.5 Flash is 75% cheaper ($10 vs $2.5) — and since output is usually the dominant cost driver, that gap matters more than it looks.

Side by side

	Claude 5 Sonnet	Gemini 2.5 Flash
Input / 1M tokens	$2	$0.3
Output / 1M tokens	$10	$2.5
Context window	1,000,000	1,000,000
Token-count accuracy	±2%	±3%
Cost — 10,000 input + 2,000 output tokens	$0.04	$0.008

What a real request costs

Take a representative turn — 10,000 input + 2,000 output tokens. Claude 5 Sonnet comes to $0.04, Gemini 2.5 Flash to $0.008. Across 100,000 requests that's a $3200 swing in favour of Gemini 2.5 Flash. To run the numbers on your actual prompt, paste it into the calculator and toggle Compare across all models.

Different leagues

These two sit in different price tiers — Claude 5 Sonnet runs roughly 5× the per-request cost of Gemini 2.5 Flash on the worked example — so they rarely compete for the same job. Reach for Gemini 2.5 Flash on high-volume, latency-sensitive work (classification, extraction, routing) and Claude 5 Sonnet only where the harder reasoning earns its price. They're different vendors, so expect a different API and tokenizer: both counts are approximate to within a few percent — budget a small calibration buffer when you switch.

See the full breakdown on the dedicated pages for Claude 5 Sonnet and Gemini 2.5 Flash.

FAQ

Is Claude 5 Sonnet or Gemini 2.5 Flash cheaper?: For a typical request (10,000 input + 2,000 output tokens), Gemini 2.5 Flash is cheaper — about 80% less, or roughly $3200 saved per 100,000 requests. Claude 5 Sonnet runs $2/$10 per 1M input/output tokens; Gemini 2.5 Flash runs $0.3/$2.5.
Which has the larger context window?: Both support a 1,000,000-token context window.
How accurate are these token counts?: Claude 5 Sonnet: Approximated with cl100k_base — drift typically <2% on English and code. Gemini 2.5 Flash: Approximated with o200k_base; drift typically ~3% on English and code. 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 platform.claude.com and ai.google.dev, verified 2026-07-06. Vendor pricing changes often — confirm before you commit.