Is Gemini 2.5 Pro or GPT-5 cheaper in 2026?

GPT-5, for every workload modelled here. On a blended 3:1 basis it costs $3.44 per million tokens against Gemini 2.5 Pro's $3.44.

Which has the larger context window?

Gemini 2.5 Pro, at 1M tokens against 400K. A larger window only helps if you can afford to fill it — the cost of one full-context request is in the table above.

Which is cheaper for output-heavy work like agents?

GPT-5, at $10.00 per million output tokens against $10.00. Reasoning tokens bill as output, so for agentic loops this axis usually decides the invoice regardless of what the input rates look like.

What is not included in these figures?

Batch-processing discounts, fine-tuning, long-context surcharges above a provider's standard tier, and any enterprise agreement. These are published pay-as-you-go list prices, checked against each provider's own pricing page on the date shown.

Gemini 2.5 Pro vs GPT-5

GPT-5 is cheaper for every workload modelled here.

List prices checked May 2026

Specifications and rates

Property	Gemini 2.5 Pro	GPT-5
Input per 1M	$1.25	$1.25
Output per 1M	$10.00	$10.00
Cached input per 1M	$0.310	$0.125
Blended (3:1)	$3.44	$3.44
Context window	1M	400K
Max output	66K	128K
Inputs accepted	text, image, audio, video	text, image

Source: Google pricing (May 2026) · OpenAI pricing (May 2026). Published list prices only — committed-use discounts, regional variation, and per-request charges are not included. Not yet independently re-checked against the vendor’s page.

Monthly cost by workload

Identical token volumes through both rate cards. Output-heavy profiles are where the ranking flips.

Workload	Gemini 2.5 Pro	GPT-5	Cheaper
In-app chat assistantA support or help assistant handling a few thousand conversations a month, with short prompts and short answers.	$75	$75	Gemini 2.5 Prosaves $0/mo
RAG over documentsRetrieval-augmented answering where each request stuffs several retrieved passages into the prompt, so input dominates.	$525	$525	Gemini 2.5 Prosaves $0/mo
Coding agentAn agentic loop that reads files and writes patches, generating heavy output and re-sending large context on every turn.	$1,500	$1,500	Gemini 2.5 Prosaves $0/mo

What each one is for

Gemini 2.5 Pro

by Google

A million-token context window with native video and audio input, priced at frontier-model rates below 200k tokens and at a higher tier above it — a detail that surprises people modelling long-context costs.

GPT-5

by OpenAI

OpenAI's flagship, priced aggressively below the other frontier models on input and with a 90% cached-input discount that makes long system prompts nearly free to reuse.

Common questions

Is Gemini 2.5 Pro or GPT-5 cheaper in 2026?: GPT-5, for every workload modelled here. On a blended 3:1 basis it costs $3.44 per million tokens against Gemini 2.5 Pro's $3.44.
Which has the larger context window?: Gemini 2.5 Pro, at 1M tokens against 400K. A larger window only helps if you can afford to fill it — the cost of one full-context request is in the table above.
Which is cheaper for output-heavy work like agents?: GPT-5, at $10.00 per million output tokens against $10.00. Reasoning tokens bill as output, so for agentic loops this axis usually decides the invoice regardless of what the input rates look like.
What is not included in these figures?: Batch-processing discounts, fine-tuning, long-context surcharges above a provider's standard tier, and any enterprise agreement. These are published pay-as-you-go list prices, checked against each provider's own pricing page on the date shown.