As of August 20, 2026, Mercury 2 is 100% cheaper per million tokens than GPT-5.5 Pro. GPT-5.5 Pro is $60.00 / $480.00 per million input/output tokens versus Mercury 2 at $0.25 / $0.75. Sources: https://developers.openai.com/api/docs/pricing and https://anotherwrapper.com/tools/llm-pricing
Sources: OpenAI API pricing (https://developers.openai.com/api/docs/pricing); AnotherWrapper LLM pricing (https://anotherwrapper.com/tools/llm-pricing)
GPT-5.5 Pro
OpenAI
Input
$60.00
Output
$480.00
Mercury 2
Inception
Input
$0.25
Output
$0.75
Token pricing, specs, and benchmarks side by side
GPT-5.5 ProMercury 2Verdict
Mercury 2 offers significantly lower pricing, while GPT-5.5 Pro leads on benchmark performance. Your choice depends on whether cost efficiency or raw capability matters more for your use case.
As of August 20, 2026, Mercury 2 is 100% cheaper on blended LLM API pricing. Mercury 2 costs $0.25 per million input tokens and $0.75 per million output tokens ($1.00 blended 1M-in + 1M-out). GPT-5.5 Pro costs $60.00 / $480.00 per million tokens ($540.00 blended). Sources: https://developers.openai.com/api/docs/pricing and https://anotherwrapper.com/tools/llm-pricing. The cheapest LLM for your app still depends on how many output tokens you generate.
GPT-5.5 Pro OpenAI API pricing is $60.00 input and $480.00 output per million tokens via OpenAI. Mercury 2 Inception API pricing is $0.25 input and $0.75 output per million tokens via Inception. Use those four numbers, not ChatGPT Plus or Claude Pro subscription prices, when you are comparing APIs.
Mercury 2 has a published LiveCodeBench score of 67%. GPT-5.5 Pro does not have that eval on this page yet.
GPT-5.5 Pro supports a 1M token context window, while Mercury 2 supports 128K tokens. GPT-5.5 Pro offers a larger context window. Filling a larger window bills more input tokens, so the cheaper-per-million model can still cost more on long documents.
GPT-5.5 Pro leads on 1 of 1 shared benchmarks versus Mercury 2's 0 wins. Check the comparison table for GPQA Diamond, SWE-bench, MMLU, HLE, and the other evals we track. Token price and benchmark score together are the usual LLM comparison, not either number alone.
Both GPT-5.5 Pro and Mercury 2 are production API models. For cost-sensitive production traffic, Mercury 2 has better economics on the blended 1M-in + 1M-out scale. For maximum capability, weight the benchmark table for your domain. Many production stacks route cheap models for drafts and a frontier model for the hard turn, which is usually cheaper than sending everything to the expensive API.
Yes. Call GPT-5.5 Pro through OpenAI and Mercury 2 through Inception with separate API keys, or through a gateway that already wraps both. Keep prompts in tokens, not characters, when you estimate the invoice. AnotherWrapper templates can swap providers without rewriting auth and billing.
List rates are the latest published OpenAI API pricing and Inception API pricing, quoted per million tokens. Official rate sheets: https://developers.openai.com/api/docs/pricing and https://anotherwrapper.com/tools/llm-pricing. Prompt caching, batch APIs, and committed-use discounts can change the invoice. Benchmark scores are from official publications and independent evals, updated as new numbers land.
GPT-5.5 Pro supports up to 128K output tokens per request, while Mercury 2 supports up to 8K output tokens. Output tokens are usually the expensive half of API pricing, so a higher max output cap is a capability, not a discount.
Mercury 2 has a measured throughput of approximately 1009 tokens/second. Throughput data for GPT-5.5 Pro is not yet available. Throughput (tokens per second) and time-to-first-token are why two models with the same per-million-token price can still feel different in chat and agents.
Use the model pickers at the top of this LLM comparison. Search any model in the index and the URL updates. Open GPT-5.5 Pro or Mercury 2 from the sidebar for the single-model API pricing page, or go back to the LLM pricing table to sort by cheapest blended cost.
This comparison covers API pricing, context window, throughput, and benchmark scores. GPT-5.5 Pro costs $60.00/M input and $480.00/M output. Mercury 2 costs $0.25/M input and $0.75/M output.
Rank both on the LLM leaderboard, SWE-bench, and Humanity's Last Exam.
The index
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