Yesterday you counted tokens. Today you learn the secret every AI company knows and most users don't: you pay per token — and the AI's answer usually costs more than your question. Let's print your first AI receipt.
Type what you'd ask the AI (that's your input). Then drag how long the AI's reply should be. The receipt updates live. Notice the two different prices!
how many tokens the AI writes back (the answer)
💵 Model price (per 1,000,000 tokens) — try changing it!
Real models charge more for OUT than IN — writing is harder work than reading.
the split of your bill: 🟦 what you sent vs 🟪 what the AI wrote back
Some of the cheapest-looking prompts are the most expensive. Tap these and watch the receipt — a tiny input can trigger a giant, pricey output.
You're given a target price. Using the current prompt and model prices, drag the answer length so the total lands within the target. Nail 3 targets to win the badge!
answer length (output tokens)
Your receipt is exactly how real AI billing works. Here's how people estimate cost, from rough to exact:
~4 characters ≈ 1 token in English. ✅ Instant mental math. ⚠️ Way off for code, numbers, and other languages.
Run the actual tokenizer, split input vs output. ✅ Accurate. ✅ Matches your bill. ⚠️ You must know each model's prices.
Every API reply reports exact input & output tokens used. ✅ Perfectly exact. ✅ Tracks caching & discounts. ⚠️ Only known after the call.
You can now read an AI receipt: input tokens + output tokens, each at its own price, added with tokens × price ÷ 1,000,000. And you learned the big trap — the AI's answer usually costs more than your question.