AI API Pricing Comparison: The 2026 Cost Guide

An AI API pricing comparison sets side by side the numbers for each provider, showing what they charge per token you put in and each token a model returns. It lets you see the cost per model before you even start building.

That table got rewritten 4 times in just a week. On September 1, Anthropic dropped one of their prices. Then on September 2, Google released a new model that already has a higher price planned for later. That same day, Meta put out another one. Then OpenAI launched GPT-6 Astra on September 3. 4 big moves over 4 days, from 3 of the top 4 players out there.

Headline prices are simple to find and just as easy to get wrong. The 2 new flagships this week show the same exact price, but your actual bill from each would be very different. And one model that looks like the cheapest actually costs you the most when you see what it charges you with. A good comparison has to show this, because the listed number isn't what you pay.

We watch all this at ChatFuse since every prompt goes through our system across more than 100 models from Google, Meta, Anthropic, OpenAI, and more. The cost of each model decides which one picks the next request. So keeping the whole price table up to date is just normal work for us. Here's how it stood in September 2026.

What prices does an AI API actually charge?

Every AI model has 4 different prices, not just one. You get charged for the tokens you send to the model and for the tokens it sends back, and on top of that, there are separate fees for writing to and reading from context cache.

What you get charged for the model's output is almost always a lot more than what you pay for your input, and reading from cache is the cheapest part of it all. Any pricing chart that shows you one single number is leaving out the other 3.

If you're not sure what a token is, we have a full post that explains how credits map to tokens. The numbers we're looking at here are the direct costs from the providers.

How do the September 2026 flagship prices compare?

The list prices really fall into 2 groups. Claude Fable 5.1 and GPT-6 Astra cost $50 for every million tokens they generate. Then you've got Meta Muse Spark 1.3 and Gemini 3.8 Flash, which are around $4 for the same amount. That's a 13x difference right there, and that's before you even look at the details that change what you actually pay.

Claude Fable 5.1 and GPT-6 Astra both run you $10 for every 1 million tokens you put in. Gemini 3.8 Flash costs $0.75 for that same input. Meta's standard tier model comes in at $1.25. You get what you pay for: the high end ones handle the toughest jobs, and the lower prices are for when you need a lot of volume. See how all 4 line up next to each other per 1M tokens, including the specifics that really affect your final cost.

Why do two models at the same price cost different amounts?

Because the number on the ad doesn't include what you pay for cached tokens or the extra costs for longer conversations. Both Claude Fable 5.1 and GPT-6 Astra show $50 for output and $10 for input. Yet reading a token from the cache costs $1 with Astra and only $0.25 with Fable 5.1. If your work uses a lot of cached context, you pay Astra 4 times more for that part.

Astra also adds another pricing level for big prompts, which Fable 5.1 doesn't do at all.

Anthropic dropped the price of a Fable cache read from $1 to just $0.25 on September 1. That's a 75% cut to one of the 4 rates they charge. The 2 main prices everyone watches didn't budge. You wouldn't see this if you were just looking at the sticker price.

What is the long context surcharge on GPT-6 Astra?

GPT-6 Astra gives you a 1,050,000 token window, but once your prompt hits about 272,000 input tokens (the reported threshold), they charge you a whole different rate. That jumps to $20 on input and $75 for output, instead of the usual $10 and $50.

Even cached reads go up from $1 to $2. So you can run the exact same model and get charged twice as much, just for a longer prompt. The big context is a real feature. This extra cost that comes with it isn't.

Are AI prices going up or down?

It depends. Some go up, some go down, and they tell you when. Take Gemini 3.8 Flash: it's $0.75 for input right now. But Google says that price becomes $1.50 on January 1, 2027. They put that doubling on the calendar. Then just look at Anthropic. That same week, they slashed a Fable cache read price by 75%. This isn't random drift. Providers are changing prices on purpose.

We put Fable 5 and GPT-5.6 up against each other a quarter ago, and those numbers are wrong now. The price you saw for an AI model a few months back isn't what you're getting charged today, and some versions just stop working completely on a schedule you don't control.

Is the cheapest AI model the cheapest bill?

Not every time, and Meta Muse Spark 1.3 shows it best. Its standard tier costs $1.25 in and $4.25 out. The Contributor tier is far less, around $0.10 for input. That's roughly 21 times cheaper than the top model.

The name tells you why. You get that lower price because Meta trains on your prompts and the answers. The cheapest tokens are the ones you pay for using your data, and that's a term you should bring up with the questions for an AI vendor before you agree to anything.

ChatFuse doesn't use a tier like that one. Your data doesn't train anyone's model here. The saving comes from routing. Most prompts don't need a $50 model. A quick answer, a bit of editing, a simple lookup, a classification, they all work fine on a model that costs about $4. The top model only handles the prompts that really require it. That's how a real bill gets cut down, and we covered how the routing works in energy efficient model routing.

How does ChatFuse price across all these models?

ChatFuse gives you more than 100 models for one subscription, and it sends each prompt to a model that's right for the job, so your cost follows the work instead of the priciest model available. That's what makes it an AI aggregator with its own routing built in.

Our ChatFuse Orchestrator looks at every single prompt, figures out what type of task it is, and picks the model that can do it for the lowest cost. We also watch for any price changes from the providers, so we're already on it. You won't have to check 4 different pricing pages every few months. We handle that. If you need to know whether this is working for you, we break it all down in measuring AI ROI.

What is the cheapest AI API in 2026?

Among current models, Gemini 3.8 Flash from Google is among the least expensive, coming in at $0.75 per million tokens for input and $3.75 for output through the end of 2026. Meta's Muse Spark 1.3 can be even cheaper on its Contributor plan, around $0.10 for input, but that price relies on Meta using your prompts for training. That's a data tradeoff the others don't ask for.

How much does GPT-6 Astra cost per token?

GPT-6 Astra charges $10 for every 1,000,000 tokens you send it and $50 for every 1,000,000 it sends back, as long as your prompt is short. Reading from its cache costs just $1. If you go over a reported limit around 272,000 input tokens, it switches to long context pricing. That's $20 for input and $75 for output. You can push up to 1,050,000 tokens into its context window and get responses as long as 128,000 tokens back.

Is Claude Fable 5.1 more expensive than GPT-6 Astra?

On paper they look the same: $10 and $50 a million for input and output tokens, both of them. But Claude Fable 5.1 charges less for cached reads, just $0.25 versus GPT-6 Astra's $1. There's no extra fee for long context either with Fable. So if your work reuses context or runs really long prompts, you'll likely pay less with Fable 5.1 even though the base prices match.

Why did my AI bill go up without changing anything?

It's almost always one of 2 things. You either went past a token threshold and hit a new pricing tier, GPT-6 Astra, for example, costs more once you cross about 272,000 tokens. Or a planned price increase just started, like Gemini 3.8 Flash going up 2x on January 1, 2027. The companies announce these changes ahead of time, so your bill can go up even if you didn't do anything new that day.

Does using multiple AI models cost more?

No, not with routing. Your ChatFuse subscription gets you more than 100 models, and we automatically send your work to the one that fits best. That means the simple jobs run on cheaper models, and a flagship only sees the hard prompts.

Most of the time, using many models actually cuts your costs instead of adding to them. It also means you aren't stuck if one provider decides to change their prices. Check out the details on our pricing page for what's included.

Where to start

The prices you see here are from September 2026, and they're all going to change. You don't need a single, frozen look at who's cheapest right now. What you need is something that tracks the shifts for you.

Sign up for a free ChatFuse account and have the system pick the right model at the right price for every task.