What AI API prices change on December 1, 2026?

As of November 12, 2026: Google's Gemini 4 Argon and Gemini 4 Carbon go from $2/$10 to $4/$20 per million input/output tokens (cache reads $0.10 to $0.20; Batch and Flex $1/$5 to $2/$10; Priority $3.60/$18 to $7.20/$36). OpenAI's promotional GPT-5.6 Sol price of $4/$20 is available only until November 30, 2026. Anthropic retires claude-sonnet-4-5-20250929 on November 30, 2026, so requests to it fail from then. Cloudflare AI Search starts billing on December 1, 2026.

Is Gemini 4 Argon getting more expensive?

Yes. Google's Gemini API pricing page lists Gemini 4 Argon at $2 per million input tokens and $10 per million output tokens through November 30, 2026, and $4 and $20 starting December 1, 2026. Gemini 4 Carbon has the identical schedule. Thinking tokens are billed as output, and neither model is on the free tier.

What happens to GPT-5.6 Sol pricing after November 30, 2026?

OpenAI's pricing page footnote says GPT-5.6 Sol's promotional pricing ($4 input, $0.40 cached, $20 output per million tokens) is available until November 30, 2026. It does not state the rate from December 1. Before the August 21, 2026 cut, GPT-5.6 Sol cost $5/$30, so budget for that. GPT-6.1 Sol, OpenAI's newer model, costs $2/$10 with no expiry stated and is the cheaper migration target.

Which cheaper models are not changing price on December 1?

Claude Sonnet 5.5 ($2/$10), Claude Opus 5.5 ($4/$20), GPT-6.1 Sol ($2/$10), GPT-6.1 Terra ($1/$5) and GPT-6 Luna ($0.10/$0.50) have no announced change on December 1, 2026. Gemini 3.8 Flash keeps its $0.75/$3.75 introductory rate through December 31, 2026, then doubles to $1.50/$7.50 on January 1, 2027.

Quick Answer

AI API Price Changes on December 1, 2026: What Changes

Published: November 12, 2026

The short answer

Four things hit AI API bills at the turn of the month. As of November 12, 2026:

Date	What changes	Before	After	Action
Dec 1, 2026	Gemini 4 Argon and Gemini 4 Carbon intro price ends	$2 / $10 per 1M tokens	$4 / $20	Re-budget, or move routine traffic to a cheaper model
Nov 30, 2026 (last day)	GPT-5.6 Sol promotional price ends	$4 / $20	Not stated by OpenAI (pre-promo list was $5 / $30)	Migrate to GPT-6.1 Sol ($2 / $10)
Nov 30, 2026	`claude-sonnet-4-5-20250929` retires on Anthropic-operated platforms	$3 / $15	Requests fail	Switch to `claude-sonnet-5-5` ($2 / $10)
Dec 1, 2026	Cloudflare AI Search billing begins	Free	Usage beyond monthly allowance billed	Check ingestion and query volumes

Next in line: Gemini 3.8 Flash goes from $0.75 / $3.75 to $1.50 / $7.50 on January 1, 2027.

Gemini 4: every line doubles

Google’s pricing page shows the same schedule for both Gemini 4 models:

Gemini 4 Argon / Carbon (per 1M tokens)	Through Nov 30	From Dec 1
Standard input / output	$2 / $10	$4 / $20
Cache reads (implicit only)	$0.10	$0.20
Batch and Flex input / output	$1 / $5	$2 / $10
Priority input / output	$3.60 / $18	$7.20 / $36

At $4/$20, Gemini 4 matches Claude Opus 5.5 ($4/$20) and is double GPT-6.1 Sol ($2/$10). Carbon reasons longer than Argon, so per-task costs differ even at the same rate. Context: is Gemini 4 available yet.

What to do: keep Gemini 4 where it wins on your evals; route bulk, latency-tolerant work to Batch or Flex (still $2/$10 after the change); move simple calls to a small model.

GPT-5.6 Sol: the promotion ends November 30

OpenAI cut GPT-5.6 Sol to $4/$20 on August 21, 2026 as a promotion. The pricing page footnote, re-read November 12, says the promotional pricing “is available until November 30, 2026” but gives no December rate. The straightforward move is GPT-6.1 Sol at $2/$10 ($0.10 cached), half the promotional price, which OpenAI positions as its price-performance model.

Claude Sonnet 4.5 retires November 30

Anthropic’s deprecations page lists claude-sonnet-4-5-20250929 as deprecated since September 30, retiring November 30, 2026 on the Claude API, Claude Platform on AWS, Anthropic-managed Google Cloud and Microsoft Foundry. Bedrock and Google-managed Vertex set their own dates. The named replacement, claude-sonnet-5-5, is cheaper at $2/$10, but it has breaking changes (thinking cannot be disabled, forced tool choice returns 400). Migration notes: Claude Sonnet 4.5 retirement: what to use instead. Also on that page: claude-opus-4-5-20251101 is active but retires “not sooner than November 24, 2026”, so watch for a date.

Cloudflare AI Search starts billing December 1

Each account keeps 5 million ingestion tokens, 10 GB-month of storage, 1,000 semantic and 1,000 full-text queries a month free. Beyond that: $0.75 per million ingestion tokens (+$0.50 for image/OCR processing), $2 per GB-month, $0.75 per 1,000 semantic queries and $0.10 per 1,000 full-text queries. A bot answering 100,000 semantic queries a month pays about $74 for queries. More in how to choose an AI knowledge layer.

A two-week checklist

Search your code and config for gemini-4-argon, gemini-4-carbon, gpt-5.6-sol and claude-sonnet-4-5.
Recompute monthly cost at the December rates; our current API prices table has both columns.
Run your eval set on the replacement model before November 30, not after.
Set billing alerts for December 1 so a doubled rate does not surprise you mid-month.

The general method is in how to budget for AI API price changes.

Last verified: November 12, 2026.