Explainer
AI subscription or API: what is the difference
A subscription and the API use the same models but are two different products. This guide is for anyone deciding between a monthly plan and pay-per-use billing: what each does, how it is billed and how the cost grows with the number of messages.
Compare these services:AI subscriptionsAI APIAI pictures and video
Head-to-head:ChatGPT vs Claude vs GeminiChatGPT vs GeminiClaude vs GeminiChatGPT vs Claude
Prepared by the Banbosh Studio editors with AI from the comparison's data; first published 12 October 2026. Facts checked on 12 October 2026 against the 4 sources listed at the end. Text last updated 12 October 2026.
The short answer
For one person writing and coding in the app, a subscription is more practical: a fixed price up to a limit. The API is for automated services (shop, support, document processing) where AI answers without a person and every token is billed.
- Comparing API and subscription prices is an illustration only: a subscription cannot power your own service and may not include the same model.
- API prices are in dollars before VAT; the table converts them at the ČNB rate.
When does a subscription fit, and when the API?
- Need: Writing, coding, questions in the app
- Better choice: SubscriptionWhy: Fixed price, the app and tools included
- Need: AI answers customers on your website
- Better choice: APIWhy: A subscription cannot be connected to your service
- Need: Processing thousands of documents
- Better choice: API (batch)Why: Batch discount and pay for use only
- Need: A developer's occasional experiments
- Better choice: API with a spending limitWhy: Small use usually means a small bill
Decision flow: subscription or API
Do you want AI inside your own app, script or automation?
Yes → You need the API; work out the cost in the API calculator.
Do you chat with AI in an app or a browser?
Yes → A subscription is simpler: a fixed amount, no tokens to watch.
Do you send only a few requests a month?
Yes → The API may cost less than a subscription; compare it at your number of messages.
No → With frequent use a subscription is more predictable; any conversion is only an orientation.
How fast does an API bill grow?
The table shows the monthly cost of three API models (the cheapest, the middle and the most expensive per message) at 100, 1,000 and 10,000 messages a month. A typical message has 1,500 input and 600 output tokens. For orientation each count also shows the cheapest advanced-tier subscription, which costs the same whatever the number of messages up to its limit.
incl. VAT
100 messages a month
| Claude Haiku 5.5 API | CZK 1.19 |
| Gemini 4 Argon API | CZK 23.74 |
| GPT-6 Astra API | CZK 119 |
| Claude Pro (subscription) | CZK 528 |
1,000 messages a month
| Claude Haiku 5.5 API | CZK 11.87 |
| Gemini 4 Argon API | CZK 237 |
| GPT-6 Astra API | CZK 1,187 |
| Claude Pro (subscription) | CZK 528 |
10,000 messages a month
| Claude Haiku 5.5 API | CZK 119 |
| Gemini 4 Argon API | CZK 2,374 |
| GPT-6 Astra API | CZK 11,872 |
| Claude Pro (subscription) | CZK 528 |
The amounts differ more than tenfold, so they are shown in a table instead of bars. Prices from the official price lists, ČNB rate of 11/6/2026. All amounts include VAT at 21%, the buyer's country rate: the API price list excludes VAT, so we added it; the subscription price includes VAT. The features and limits of a subscription and the API are not the same.
Exact values
| Model / messages a month | 100 | 1,000 | 10,000 |
|---|---|---|---|
| Claude Haiku 5.5 API | CZK 1.19 | CZK 11.87 | CZK 119 |
| Gemini 4 Argon API | CZK 23.74 | CZK 237 | CZK 2,374 |
| GPT-6 Astra API | CZK 119 | CZK 1,187 | CZK 11,872 |
excl. VAT
100 messages a month
| Claude Haiku 5.5 API | CZK 0.98 |
| Gemini 4 Argon API | CZK 19.62 |
| GPT-6 Astra API | CZK 98.12 |
| Claude Pro (subscription) | CZK 436 |
1,000 messages a month
| Claude Haiku 5.5 API | CZK 9.81 |
| Gemini 4 Argon API | CZK 196 |
| GPT-6 Astra API | CZK 981 |
| Claude Pro (subscription) | CZK 436 |
10,000 messages a month
| Claude Haiku 5.5 API | CZK 98.12 |
| Gemini 4 Argon API | CZK 1,962 |
| GPT-6 Astra API | CZK 9,812 |
| Claude Pro (subscription) | CZK 436 |
The amounts differ more than tenfold, so they are shown in a table instead of bars. Prices from the official price lists, ČNB rate of 11/6/2026. All amounts exclude VAT (21%, the buyer's country rate): the API price list excludes VAT, and we removed VAT from the subscription price. The features and limits of a subscription and the API are not the same.
Exact values
| Model / messages a month | 100 | 1,000 | 10,000 |
|---|---|---|---|
| Claude Haiku 5.5 API | CZK 0.98 | CZK 9.81 | CZK 98.12 |
| Gemini 4 Argon API | CZK 19.62 | CZK 196 | CZK 1,962 |
| GPT-6 Astra API | CZK 98.12 | CZK 981 | CZK 9,812 |
incl. VAT
Claude Pro at CZK 528 a month against the API of GPT-6 Astra API: in this model calculation the amounts are equal at 444 messages a month, with Claude Haiku 5.5 API at 44,444. The features and limits of a subscription and the API are not the same.
A typical message of 1,500 input and 600 output tokens, no cache or batch discount; official price lists, rate of 11/6/2026. All amounts include VAT at 21%, the buyer's country rate: the API price list excludes VAT, so we added it; the subscription price includes VAT. The break-even point is the same with and without VAT; only the amounts change.
excl. VAT
Claude Pro at CZK 436 a month against the API of GPT-6 Astra API: in this model calculation the amounts are equal at 444 messages a month, with Claude Haiku 5.5 API at 44,444. The features and limits of a subscription and the API are not the same.
A typical message of 1,500 input and 600 output tokens, no cache or batch discount; official price lists, rate of 11/6/2026. All amounts exclude VAT (21%, the buyer's country rate): the API price list excludes VAT, and we removed VAT from the subscription price. The break-even point is the same with and without VAT; only the amounts change.
What does a subscription cost a year?
For comparison with an API bill: the yearly cost of paid AI plans from today's price list, paid monthly and paid yearly where the provider offers it.
paid monthlypaid yearly
- Gemini Google AI PlusCZK 1,800
- ChatGPT GoCZK 2,904
- Claude ProCZK 6,332
- CZK 5,277
- Gemini Google AI ProCZK 6,600
- ChatGPT PlusCZK 7,245
Amounts include VAT; where a price list excludes it, we add the country's rate. A price list that does not state VAT is shown as listed.
How do a subscription and the API differ?
- Billing: a subscription is a fixed monthly amount up to a limit; the API charges per million input and output tokens.
- Use: a subscription is an app for a person; the API is an interface for a program.
- Models: the API also offers cheap models for large volumes that the app may not have.
- Limits: a subscription has a usage limit; the API a spending and request limit you set.
Plans at today's price
Who it is for
- You are deciding how to use AI in a company.
- You code and consider paying per token instead of a plan.
- You want to estimate an API bill by number of messages.
Watch out for
- Output tokens cost more than input and make up most of the bill for long answers.
- Without a spending limit a bug can send thousands of requests an hour.
- Non-English text splits into more tokens than the same English text.
- Repeated instructions without the cache are paid with every message.
Frequently asked questions
- Is the API cheaper than a subscription?
- With few messages and a cheap model it often is, but a subscription includes the app and tools the API lacks. For an automated service the API is the only option.
- Can I use a subscription for a chatbot on my site?
- No. Connecting your own service is what the API is for.
- What is batch processing?
- You send the tasks at once and get the results later. Some providers charge half the usual price for it.