AI API cost calculator — vibe coding, agents & production apps

How it works

Each preset is calibrated from real-world data — Anthropic official benchmarks, Cursor forum reports, Cline GitHub issues. Pick a preset → adjust prompts per day → read the subscription breakeven table. The table now includes CloudyBot flat-rate plans alongside Cursor Pro, Claude Pro, and GitHub Copilot so you can compare all your options in one place. New to tokens and caching? The plain-English explainer below covers everything from scratch. Pricing verified 2026-04-17 with links to each provider’s pricing page.

Who this calculator is for

• Vibe coders on Cursor / Windsurf / Copilot / Cline — wondering whether to use your own API key or just subscribe. Load the matching preset and compare vs the subscription breakeven panel.
• Claude Code / OpenClaw users — load the preset, set your real prompts/day, and see your monthly exposure vs Claude Pro. See the FAQ for OpenClaw-specific details.
• Teams pitching a budget — translate "we send ~200 messages/day to GPT-4.1" into a monthly API line item with a low/mid/high range.
• Model routing decisions — use the Blend panel to route cheap queries to GPT-4.1 nano / Gemini 2.0 Flash and only flagship queries to Claude Sonnet 4.

AI costs explained simply — no jargon

Not familiar with tokens, caching, or API pricing? Here's everything you need to know, explained with plain analogies.

🧮 What is a "token"?

A token is roughly ¾ of a word. "Hello world" = 2 tokens. "authentication" = 4 tokens. A line of code like const user = await db.getUser(id); is about 12 tokens. Every word you type and every word the AI writes back gets counted as tokens — that's what you're billed for.

Real example: You type "fix this bug" (4 tokens). But Cursor also silently attaches your open files (maybe 8,000 tokens), its own system instructions (2,000 tokens), and conversation history (5,000 tokens). So the AI actually receives ~15,000 tokens even though you typed 4 words. That's normal — and that's why costs add up faster than people expect.

💸 How does billing work?

AI providers charge separately for input tokens (everything you send) and output tokens (everything the AI writes back). Output tokens cost 3–5× more per token on most models, because generating text is harder than reading it.

Think of it like a taxi: the ride starts the moment you get in (input cost), but the meter ticks faster on the highway (output cost). A long conversation where you paste a 500-line file and the AI rewrites the whole thing? That's an expensive trip.

🔄 What is caching — and why does it matter so much?

Imagine a photocopier that charges you full price the first copy, but 10 cents on the dollar for reprints of the same page. That's prompt caching.

The first time Cursor sends your codebase to the AI, you pay full price. On the next prompt (in the same session), those same file contents are "cached" — you pay only 10% of the original price to re-read them. This is why the Cursor preset has 80% cache: 80% of your huge token volume is cheap reprints, not full-price reads. Without caching, Cursor would cost 5–10× more.

The catch: caching only works within a session. Close Cursor and reopen it — the cache is cold again. That first prompt of the day costs full price.

🤖 Why do coding agents (Claude Code, Cline) cost so much more?

When you type one message to Claude Code, it doesn't just answer once. It runs a loop: read the file → think → write a change → run the tests → read the output → think again → fix the error → done. Each step in that loop is a separate API call, each with its own tokens. 4 loops per message = 5× the API calls for that one prompt you sent.

Claude Code also carries a mandatory 14,328-token overhead in every single call — that's its system instructions and tool definitions, sent every time, before your code is even mentioned. At $3/M input, that's about $0.04 just to start each turn. It adds up.

📊 Subscription vs API key — which is cheaper?

A subscription like Cursor Pro ($20/mo) is a flat fee that covers your usage up to a cap, after which the tool quietly routes you to slower/cheaper models. A direct API key charges you per token but always uses exactly the model you chose.

• Light user (under 20 prompts/day): Subscribe. You'll probably spend less than $20/mo on pure API anyway, and the subscription gives you extras (IDE features, routing intelligence, no billing setup).
• Heavy user (40+ prompts/day on flagship models): Direct API can win, especially if you mix in cheaper models like GPT-4.1 mini or DeepSeek V3 for simple questions.
• Unpredictable usage: API keys can surprise you at month-end. A heavy week of coding can cost 5× a light week, and there's no ceiling.

The subscription breakeven panel in the Results section calculates the exact crossover for your scenario.

📐 How to read this calculator

The three most impactful inputs are: (1) tokens per prompt — most people underestimate this; use 40K for Cursor, 30K for Claude Code, not 1K. (2) cache % — if you use Cursor in a long session, set it to 80%; if you use Cline or start fresh sessions often, set it lower (20–30%). (3) tool rounds — set to 0 for chat, 1 for Cursor, 4 for Claude Code, 4–6 for Cline. These three numbers together determine 90% of your bill.

API billing vs flat-rate AI plans: which is cheaper?

Per-token API billing is the right model when you need full control — building your own product, picking specific models, handling unpredictable volume patterns. The cost scales linearly with usage, which is perfect for low-volume automation but painful for heavy daily use where a busy week costs 5× a quiet one.

Flat-rate plans (Cursor Pro, Claude Pro, CloudyBot) work the opposite way: fixed monthly price, known ceiling, predictable budgeting. The tradeoff is that you get a capped number of requests or "tasks" instead of unlimited tokens. Below a certain usage level, subscriptions almost always win on price. Above it, direct API often wins — but only if you're deliberate about model routing (using cheaper models for simple queries).

The subscription breakeven table in the Results panel calculates your crossover live. CloudyBot is included alongside Cursor Pro, Claude Pro, and GitHub Copilot — but note that CloudyBot is a different product category (AI workers for research, automation, and operations — not an IDE). The comparison is useful for anyone evaluating where their AI budget should go across different jobs.

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