AI API Pricing Comparison | 2026 Complete Guide to OpenAI, Claude, and Gemini Pricing

Why You Need to Understand AI API Pricing: Saving Money Starts with Understanding Billing

Did you know? Generating the same 1,000-word article summary with Claude Fable 5.1 versus Gemini 2.5 Flash-Lite can differ in cost by over 100x.

Choose the wrong model and you could waste thousands of dollars a month. Even worse, many teams have no idea why their AI API bills keep climbing — because they've never seriously compared pricing structures.

This article breaks down the 2026 pricing of the three major AI API platforms (OpenAI, Claude, Gemini) line by line, helping you find the "good enough yet cheapest" combination.

Want enterprise discount pricing right away? Contact the CloudInsight team for the most cost-effective AI API procurement plan.

TL;DR

2026 AI API pricing varies enormously: among the models listed here, Gemini 2.5 Flash-Lite is the cheapest ($0.10 input / $0.40 output per million tokens, existing users only; the lowest-priced Gemini model open to new projects is 3.1 Flash-Lite at $0.25/$1.50, though it is scheduled to shut down on 2027-05-07 at the earliest), while Claude Fable 5.1 and GPT-6 Astra are the most expensive ($10/$50).

Complete Pricing Overview for the Three Major AI APIs | Token Pricing at a Glance

Answer-First: As of October 2026, input prices for the mainstream models in this article range from $0.10 per million tokens (Gemini 2.5 Flash-Lite, GPT-6 Luna, and Claude Haiku 5.5 for prompts up to 100K tokens; Haiku 5.5 is $0.50/$2.50 above 100K) to $10 (Claude Fable 5.1, GPT-6 Astra), and the output spread is wider ($0.40 to $50). Choosing the right model tier is the first step to controlling costs.

Here's the token pricing comparison for the major models across all three platforms:

Price sources: OpenAI, Claude, Gemini (verified 2026-09-30; GPT-5.6 Luna/Terra were cut on 2026-07-30 and GPT-5.6 Sol on 2026-08-21, with Sol's price labeled promotional through at least 2026-11-21; Gemini 3.8 Flash's $0.75/$3.75 is an introductory price that rises to $1.50/$7.50 on 2027-01-01. The Claude Haiku 5.5, GPT-6.1 Terra and Gemini 4 Argon rows were added on 2026-10-28; Gemini 4 Argon's $2/$10 applies through 2026-11-30 and rises to $4/$20 from 2026-12-01. For the GPT-5.4-nano shutdown date, see OpenAI deprecations)

⏰ Two Points People Get Wrong

1. Claude Sonnet 5's $2/$10 is the standard price, not an introductory one The rate was first announced as a launch price that would later move to $3/$15, but Anthropic has since corrected the record on its pricing page: $2/$10 is now the standard price, and the planned increase to $3/$15 will not occur. If you padded your budget for a 50% jump, you can plan on $2/$10 instead.

2. Retired models — stop hardcoding them

• Gemini 2.0 Flash and 2.0 Flash-Lite: shut down June 1, 2026
• Claude Opus 4.1, Opus 4, Sonnet 4 and Haiku 3.5 are retired (still available on some cloud platforms only)
• Claude Fable 5 ($10/$50), Opus 5 and Opus 4.8 / 4.7 / 4.6 / 4.5 (all $5/$25), Sonnet 5 ($2/$10), Sonnet 4.6 ($3/$15) and Haiku 4.5 ($1/$5) are listed by Anthropic under Legacy models — still callable, but no longer the current lineup. The current lineup is Claude Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5 (see the official models overview)
• Claude Sonnet 4.5 ($3/$15): Anthropic announced its deprecation on September 30, 2026; it retires on November 30, 2026, and the recommended replacement is Sonnet 5.5 (see the official deprecations page)

⚠️ Before You Compare: Token Counts Are Not Comparable

Most comparison articles miss this. Anthropic's documentation states that Claude Opus 4.7 and later models (including the current Fable 5.1, Opus 5.5 and Sonnet 5.5) use a newer tokenizer that produces roughly 30% more tokens for the same text.

Meaning: if your token counts were measured on an older Claude model, expect about 30% more on these newer models and recompute the cost with the new token counts. Across vendors, tokenizers differ and there is no official conversion ratio, so what matters is the cost of completing the same task — measure token counts on the same data with each vendor rather than relying on list prices.

How Token Billing Works

What's a token? Simply put, 1 token is approximately:

• English: 0.75 words (i.e., 1,000 tokens is about 750 English words)
• Chinese: the ratio depends on each vendor's tokenizer — measure it with the official token-counting tools

AI API billing splits into Input Tokens (content you send to the AI) and Output Tokens (content the AI sends back). For the models listed here, output is priced at roughly 4-8x input.

What does this mean in practice? Suppose the AI generates a long article with 4,000 output tokens. Here's the cost difference across models:

Based on 4,000 output tokens. If your token counts were measured on an older Claude model, Claude models on the new tokenizer (Fable 5.1, Opus 5.5, Sonnet 5.5, Haiku 5.5) will use ~30% more; tokenizers differ across vendors, so measure token counts on the same data. Gemini 3.8 Flash is at its introductory price through 2026-12-31; output rises to $7.50 from 2027-01-01; GPT-5.6 Sol is at a promotional price ($4/$20, officially available at least through 2026-11-21).

The difference is crystal clear: over 100x between the most and least expensive.

---

OpenAI API Pricing Breakdown | Choosing Between GPT-6 and GPT-5.6

Answer-First: OpenAI launched the GPT-6 family in September 2026: GPT-6 Astra (flagship) on September 3, GPT-6 Sol and GPT-6 Luna on September 22, and GPT-6.1 Sol on September 29, followed by GPT-6.1 Terra on October 26. GPT-5.6 (Sol / Terra / Luna), which went GA on July 9, 2026, is still on sale. On price, GPT-6 Luna is now OpenAI's cheapest new model; reach for Astra only when you need maximum capability.

OpenAI has the most complete product lineup, but also the most complex pricing. Let's break it down:

The GPT-6 Family: The Current Lineup Since September 2026

GPT-6 Astra is OpenAI's most capable model, at $10 input / $50 output per million tokens. GPT-6.1 Sol costs $2/$10 and targets complex coding and professional work at a lower cost than Astra; GPT-6 Luna costs $0.10/$0.50 for high-volume, repeatable tasks. GPT-6.1 Terra, launched October 26, 2026, costs $1/$5 ($0.05 cached input); OpenAI positions it for visual reasoning, precise computer use and natural writing, and tool calling requires the Responses API. GPT-6 Sol costs half of GPT-5.6 Sol's promotional price; GPT-6 Luna's input is half of GPT-5.6 Luna's and its output less than half.

GPT-5.6 Sol: Previous Flagship, For High-Difficulty Tasks

Sol is the strongest tier in the GPT-5.6 family. After the August 21, 2026 price cut, input costs $4 per million tokens and output $20 (labeled promotional, through at least 2026-11-21).

Ideal scenarios:

• Complex logical reasoning and analysis
• High-quality long-form content generation
• Tasks requiring top benchmark performance

Not ideal for: routine text processing, high-volume batch tasks, budget-constrained projects

GPT-5.6 Terra: Previous Balanced Tier

Terra is the balanced tier. After the July 30, 2026 price cut, input is $2.00/M tokens and output $12.00/M — half Sol's input price and 60% of its output price.

GPT-5.6 Luna: Previous Value Tier

If your task doesn't need top-tier reasoning, Luna is worth considering. After the July 30, 2026 price cut, input is just $0.20/M tokens and output $1.20/M — a twentieth of Sol's input price and about a seventeenth (6%) of its output price — yet it performs well enough on most basic tasks.

An Older Light Tier: GPT-5.4-mini / nano

The older 5.4 generation also remains on sale, though it is no longer the cheapest option:

• GPT-5.4-mini: $0.75 / $4.50
• GPT-5.4-nano: $0.20 / $1.25 (the newer GPT-6 Luna, at $0.10 / $0.50, is cheaper). On 2026-10-01 OpenAI announced that gpt-5.4-nano will shut down on 2027-04-01, recommending gpt-6-luna instead (see OpenAI deprecations)

OpenAI Cost-Saving Features

• Batch API: Non-real-time tasks can use batch mode for a 50% discount
• Cached Input: Repeated System Prompts are cached automatically, saving about 90% (cached input is 10% of the base price on GPT-5.4/5.6 and GPT-6 Astra/Sol/Luna; 5% on GPT-6.1 Sol and GPT-6.1 Terra)
• Fine-tuning: the self-serve fine-tuning section of the OpenAI deprecations page lays out the timeline for winding down the fine-tuning platform, which no longer accepts new users (the pricing page carries the same notice), so it is not a cost-saving route for new projects

For complete OpenAI API pricing details, see OpenAI API Pricing: Full Breakdown.

---

Claude API Pricing Breakdown | Cache Reads Save Up to 97.5%

Answer-First: Claude API's biggest advantage is its Prompt Caching mechanism, which cuts the cost of re-reading repeated long prompts to 10% of the base input price (5% on Opus 5.5 and Sonnet 5.5, 2.5% on Fable 5.1). The discount applies only to the input tokens that hit the cache, not to your whole bill; uncached input and output are billed at normal rates, and cache writes cost more than base input. OpenAI also caches automatically, so the real difference depends on your cache hit rate and the models you choose.

The Anthropic Claude model family has four tiers:

Fable 5.1: Mythos Class, Top Tier

Fable 5.1 is the highest tier Anthropic sells publicly. Input at $10/M tokens, output at $50/M tokens. Mythos 5.1 sits at the same price with limited availability; the previous Fable 5 is now a legacy model at the same price. For Fable 5's full usage-cost scenarios and Taiwan procurement, see Claude Fable 5 API Pricing Explained.

Opus 5.5: Default Recommendation

Opus 5.5 is Anthropic's current Opus-class model; its models overview says that if you're unsure which model to use, start with Opus 5.5 for most workloads. Input at $4/M tokens, output at $20/M tokens — 20% cheaper than the previous Opus 5 ($5/$25, now legacy) and the same price as GPT-5.6 Sol's promotional rate ($4/$20).

Note 1: Opus 4.8 now sits under Anthropic's "Legacy models" heading — still callable, still $5/$25, but no longer the current model. Any claim that Opus 4.8 is the sitting flagship is out of date.

Note 2: Opus 4.1 ($15/$75) is retired (still available only on Bedrock and Google Cloud). If you see a claim that "Claude's flagship costs $15/$75," that is the old price; the current Opus 5.5 is $4/$20.

Sonnet 5.5: Best Balance

Sonnet 5.5 is the current Sonnet-class model: input at $2/M tokens and output at $10/M. The previous Sonnet 5 is now a legacy model, also at $2/$10 — that is the standard price, not an introductory one. Anthropic has stated that the planned increase to $3/$15 will not happen.

It includes a 1 million token context window at standard rates (no long-context surcharge), which suits long-document processing.

Haiku 5.5: Fast and Low-Cost

Haiku is the lightweight option. Haiku 5.5, launched October 7, 2026, has two price tiers: $0.10 input / $0.50 output per million tokens for prompts up to 100K tokens, and $0.50 / $2.50 for prompts above 100K tokens; it also has a 1M-token context window. Ideal for real-time chatbots and high-volume batch processing.

The previous Haiku 4.5 ($1/$5) is still callable; Anthropic now lists it as a legacy model, succeeded by Haiku 5.5.

Three Ways to Save with Claude

1. Prompt Caching: Cache your System Prompt, and cached reads cost only 10% of the original price (5% on Opus 5.5 and Sonnet 5.5, 2.5% on Fable 5.1). If your application has a fixed long System Prompt (like a customer service bot's configuration), this feature is incredibly useful.
2. Batch API: Non-real-time tasks get a 50% discount, with results returned within 24 hours.
3. Tune thinking with effort: Fable 5.1, Opus 5.5 and Sonnet 5.5 use adaptive thinking (always on for the first two), and the effort parameter controls how much they think; more thinking costs more tokens but improves accuracy on complex tasks and reduces retries. The old extended-thinking setting is not accepted on these three models; the older Haiku 4.5 still uses extended thinking and does not support effort.

For more Claude API pricing details, see Claude API Pricing: Complete Guide.

---

Gemini API Pricing Breakdown | The Most Generous Free Tier in AI APIs

Answer-First: Gemini API still offers the broadest free tier across text models, which suits prototyping. But Google no longer publishes fixed quota figures.

Google AI Studio Free Version

Gemini's free version is the most generous of all AI APIs:

• Quota varies by account tier — check yours in AI Studio; the old quota figures still circulating online no longer apply
• Covers the current workhorse 3.8 Flash, plus 3.6 Flash, 3.5 Flash-Lite, 3.1 Flash-Lite and the 2.5 family (3.7 Flash and 3.5 Flash were deprecated on October 8, 2026; their endpoints now route automatically to 3.8 / 3.6 Flash, and AI Studio no longer offers them)
• No free tier for the flagship Gemini 4 Argon, which became generally available on October 13, 2026

The free version has Rate Limits that make it unsuitable for production, but it's more than enough for prototyping, learning, and personal projects.

Gemini Enterprise Agent Platform (formerly Vertex AI)

Enterprise users can move to Google Cloud's Gemini Enterprise Agent Platform (formerly Vertex AI); the enterprise options Google lists include dedicated support, Provisioned Throughput and volume-based discounts.

Context Window: No Longer a Gemini-Only Advantage

Gemini's long-standing selling point was its 1-million-token context window. In 2026 that gap has closed — Claude 4.6 and later models (including the current Fable 5.1, Opus 5.5 and Sonnet 5.5) all include a 1M-token context window at standard pricing (a 900k-token request bills at the same per-token rate as a 9k-token one). The one exception is Haiku 5.5: it also has 1M tokens, but a request whose prompt exceeds 100K tokens is billed at $0.50/$2.50.

So long context on its own is no longer the deciding reason to pick Gemini — compare unit price and real task cost instead.

For the full Gemini API feature set, see Gemini API Complete Guide.

Looking for free AI APIs? Check out Free AI API Recommendations.

---

Head-to-Head Cost Comparison | Actual Spending Tests for Identical Tasks

Answer-First: Computed from official list prices, the same task can differ by over 100x between the cheapest and most expensive model. But cost is only half of model selection — judge quality with your own task evaluation. This section does not publish quality scores.

On quality scores: this article does not publish per-model quality scores. What follows is cost computed from official list prices only. Judge quality with your own task evaluation — model rankings shift a lot by task, and any single scorecard can mislead.

Three common scenarios, with costs converted from official rates (cost only, not a quality ranking):

Scenario 1: Generate a 1,000-Word Chinese Article Summary

Assuming 3,000 input tokens and 1,500 output tokens:

Scenario 2: Analyze a 50-Page PDF Document

Assuming 100,000 input tokens and 2,000 output tokens:

Scenario 3: Generate Python Code

Assuming 1,500 input tokens and 3,000 output tokens (code output runs long):

Arithmetic from official list prices (checked 2026-09-30). If your token counts were measured on an older Claude model, Claude models on the new tokenizer (Fable 5.1, Opus 5.5, Sonnet 5.5, Haiku 5.5) will use ~30% more; tokenizers differ across vendors, so measure token counts on the same data. Gemini 3.8 Flash is at its introductory price through 2026-12-31; GPT-5.6 Sol is at a promotional price ($4/$20, officially available at least through 2026-11-21).

Key Finding: There's no single "one model to rule them all." The longer your output, the more the output rate dominates — scenario 3 has twice as many output as input tokens, and models with expensive output pull away immediately. The smart approach is to match different models to different task types.

For a more detailed AI API comparison, see How to Choose an AI API? Complete Comparison Guide.

---

Five Strategies to Save on AI APIs | Essential Cost Optimization for Enterprises

Answer-First: Based on practical experience, implementing these five strategies can reduce AI API costs by 40-70%.

Strategy 1: Route Tasks to the Right Models

Not every task needs the most expensive model. Build a "model router":

• Simple tasks (classification, summarization) -> GPT-6 Luna or Gemini 3.5 Flash-Lite (existing users can stay on 2.5 Flash-Lite)
• Standard tasks (copywriting, translation) -> Claude Sonnet 5.5, Gemini 3.8 Flash or GPT-6.1 Sol
• Complex tasks (reasoning, analysis) -> GPT-6 Astra, Claude Opus 5.5 or Claude Fable 5.1

Strategy 2: Leverage Prompt Caching

If your application has a fixed System Prompt, always enable caching:

• OpenAI Cached Input: saves about 90% (95% on GPT-6.1 Sol and GPT-6.1 Terra)
• Claude Prompt Caching: saves 90% (95% on Opus 5.5 and Sonnet 5.5, 97.5% on Fable 5.1)

Strategy 3: Batch Processing for Lower Costs

Non-real-time tasks (like daily reports, batch translations) can save 50% using the Batch API.

Strategy 4: Monitor Usage and Set Budget Caps

Every platform has a Usage Dashboard. Recommendations:

• Set monthly budget caps
• Set usage alerts (notify at 80%)
• Review token consumption distribution weekly

Strategy 5: Get Enterprise Discounts Through a Reseller

Enterprise bulk purchases of AI API tokens can qualify for additional discounts through resellers. CloudInsight offers enterprise procurement for OpenAI, Claude, and Gemini with discounts and Taiwan Government Uniform Invoices. To compare resellers, see How to Choose an AI API Reseller: What to Check.

For more cost optimization tips, see LLM API Cost Optimization Strategies.

---

Need a More Precise AI API Cost Estimate?

CloudInsight offers AI API enterprise procurement with exclusive discounts, Government Uniform Invoices, and local technical support.

Get an Enterprise Quote Now

---

FAQ: AI API Pricing Common Questions

Do AI APIs cost money? Are there completely free options?

The Gemini API offers a free tier on most text models, though Google no longer publishes fixed quota numbers — check your own limits in AI Studio. OpenAI and Anthropic bill API usage through prepaid credits you buy before use. Free tiers carry rate limits and aren't suitable for production.

How much does an AI API cost per month?

It depends entirely on usage volume and model choice. Personal small projects can be kept within $5-20/month. Mid-size enterprises typically spend $100-1,000/month. Large enterprises may spend $10,000+ per month. Choosing the right model tier is key to controlling costs.

Which AI API is cheapest for developers?

Purely on price, Gemini 2.5 Flash-Lite is the cheapest model in this article's table ($0.10 input / $0.40 output per M tokens); OpenAI's older gpt-5-nano ($0.05 / $0.40) is even lower on input, but it shuts down on 2026-12-11 (OpenAI recommends gpt-5.6-*), so don't start new projects on it. Note that Gemini 2.5 Flash-Lite is only open to users who have used it before; the lowest-priced Gemini model for new projects is 3.1 Flash-Lite ($0.25 / $1.50), though it is scheduled to shut down on 2027-05-07 at the earliest with 3.5 Flash-Lite ($0.30 / $2.50) as its successor. On the Claude side, the cheapest option is Haiku 5.5 ($0.10 / $0.50 for prompts up to 100K tokens, $0.50 / $2.50 above). But "cheapest" doesn't mean "best choice" — you also need to consider model capability, API stability, and community support. Start with free tiers to test, then decide on a paid plan.

What exactly are tokens? How are costs calculated?

Tokens are the smallest unit AI uses to process text. 1,000 tokens equals roughly 750 English words (the ratio for Chinese depends on the tokenizer). AI APIs bill separately for Input Tokens (text you send) and Output Tokens (AI's response), with output priced at roughly 4-8x input for the models listed here.

Are there discounts for heavy enterprise AI API usage?

Yes. Anthropic's pricing page says volume discounts may be available for high-volume users, negotiated case by case. Additionally, purchasing through resellers like CloudInsight can yield extra discounts, Government Uniform Invoices, and local technical support.

---

Choosing the Right AI API | Price Isn't the Only Factor

When choosing an AI API, cost is obviously important, but it's not the only consideration. Here are my recommendations:

• Budget-constrained individual developers -> Gemini Flash-Lite (has a free tier, lowest list price in this article)
• General enterprise applications -> Claude Sonnet 5.5, Gemini 3.8 Flash or GPT-6.1 Sol (balanced performance and price)
• Need maximum capability -> GPT-6 Astra, Claude Opus 5.5 or Claude Fable 5.1 (choose based on task)
• Need Government Uniform Invoices and local support -> Through CloudInsight enterprise procurement

The AI API landscape changes fast — pricing and model capabilities update every few months. Bookmark this article and check back for the latest information.

---

Get the Best AI API Plan for You

CloudInsight offers enterprise procurement for OpenAI, Claude, and Gemini:

• Enterprise-exclusive discounts, cheaper than list prices
• Taiwan Government Uniform Invoices, solving reimbursement challenges
• Chinese-language technical support, instant issue resolution

Get an Enterprise Quote Now | Join LINE for Instant Consultation

---

References

• OpenAI API official pricing
• Claude API official pricing
• Gemini API official pricing
• Gemini API rate limits (free quota lookup)
• Gemini API models and deprecations
• Claude models overview and Claude Haiku 5.5 overview
• OpenAI model deprecations

1. OpenAI Platform - Pricing (2026)
2. Anthropic - Claude API Pricing (2026)
3. Google AI for Developers - Gemini API Pricing (2026)
4. OpenAI - Tokenizer Documentation
5. Anthropic - Prompt Caching Documentation

Further Reading

• Billing model trends: What is TaaS? Token billing in the AI era explained (June 2026)
• GPT-5.6 Sol / Terra / Luna: How to Choose, and What Multi-Cloud Availability Means