The same $20 spent on API tokens buys a surprising amount of text. A worked example at $2 in / $10 out per million tokens, in words per month, and the honest reason the seat still usually wins for chat.
In this lesson you will
→Convert $20 of API credit into words per month at a real rate
→See why the subscription still wins for conversational use
→Know which of your jobs would be cheaper on the API
Before you pay a flat $20, it is worth knowing what the same money buys when you pay per word instead. Not because you should switch (most beginners should not), but because the comparison tells you what kind of user you are.
Figure 1.A subscription is a flat fee for an app with usage caps. The API is a meter: you pay for every token in and out, with no app and no cap except your own.
The worked example
Take a frontier model at $2 per million input tokens and $10 per million output tokens (Claude Sonnet 5's catalogue rate on 2026-09-12; GPT-5.4 and Gemini 3.1 Pro sit nearby). A token is about three-quarters of a word. A typical assistant turn is around 400 tokens in (your message plus recent history) and 300 tokens out (roughly 230 words of answer).
What $20 buys at $2 in / $10 out per million tokens. Round numbers; the arithmetic is the point.
Step
Arithmetic
Result
Cost of one turn's input
400 ÷ 1,000,000 × $2
$0.0008
Cost of one turn's output
300 ÷ 1,000,000 × $10
$0.0030
Cost per turn
$0.0008 + $0.0030
$0.0038
Turns per $20
$20 ÷ $0.0038
about 5,260 turns a month
Words of answers per $20
5,260 × 230 words
about 1.2 million words
Turns per day
5,260 ÷ 30
about 175 a day
So $20 of API credit on a frontier model buys roughly 1.2 million words of answers a month, or 175 conversational turns a day. Almost nobody sends 175 messages a day. That is the honest case for the subscription: for a normal chat user, the seat and the API cost about the same, and the seat comes with the app. The API only pulls ahead when the work is not conversation.
Knowledge check
At $2 in / $10 out per million tokens, a turn of 400 input and 300 output tokens costs about $0.0038. Roughly how many such turns does $20 buy?
For ordinary chat, not by enough to matter: $20 of frontier-model API credit buys roughly 5,000 conversational turns a month, which is more than a typical person uses, so the seat costs about the same and includes the app. For bulk, repetitive tasks the API is dramatically cheaper because a small model does them for cents.
▸How many words does $20 of API buy?
At $2 in / $10 out per million tokens, with typical turn sizes, roughly 1.2 million words of answers a month. On a budget model at a tenth of that rate, ten times more. Your exact figure depends on how long your messages and answers are.
▸Do I need to code to use the API?
A little, or a tool that hides it. First Output 101 gets a non-programmer to a working call in one lesson. If you only chat, you never need it; the seat is the right product.
Finished reading?
Mark it done to track your progress through the course.
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