The Math Behind Every Question: How Pricing Works in Astrology Bot
What Happens When You Ask a Question
Your single question isn't a single AI call. Depending on the question type, the system makes between two and ten requests to Claude:
- ◆Classification — the model determines what exactly you're asking (full analysis? follow-up? just a greeting?)
- ◆Planning — a plan is generated: which houses and planets need to be analyzed
- ◆Energy text generation — for each point in the plan, a detailed analysis is created (if it's not already in the cache)
- ◆Synthesis — all texts are assembled into a final answer to your specific question
Each of these calls means specific tokens, for which Claude charges me specific money. But the Claude API isn't the only expense.
Cost Layers
Claude API + Tax
The main expense. Claude charges by tokens — separately for input (your question + context) and output (the response). Sonnet is cheaper, Opus is more expensive, roughly 5 times so.
But there's a nuance: when purchasing credits, Anthropic adds 24% tax. That means $100 in credits costs me $124. This means the real cost of every token for me is a quarter higher than what's listed in Claude's pricing.
Astrology API
Natal chart calculation — planetary positions, house cusps, aspects — is done through an external API. The subscription costs $49 per month. With a small number of users, this is a noticeable fixed expense.
Stripe
For every payment, Stripe takes 2.9% + €0.25. On small amounts, the fixed portion of the fee eats a noticeable percentage — which is why the minimum top-up is €5.
Infrastructure
Server, domain, SSL, database. Modest for now — a single server. But it's still money.
Development
My hours as a developer and as an astrologer. The prompts the system uses are the result of several months of work and several hundred euros in testing. This isn't factored into the price directly, but the sales multiplier partially covers it.
Concrete Numbers
Adding a chart (initialization — generating 12 houses + core personality) costs me just over €1 per chart.
Each question with analysis costs me around €0.20 — on Sonnet. On Opus it's more expensive, roughly 4–5 times so.
Follow-ups (clarifying questions within the same topic) don't require a new plan or generation from scratch, but they're not free either: the context includes all the session's astrology, the core personality, the entire conversation, and additional energy texts may be pulled in. Context grows — and with it, input tokens. Simple questions without astrology are very cheap — a single model call.
Why the More You Chat, the Cheaper It Gets
This is the key idea behind the caching system I write about separately.
The energy text for the 3rd house in your chart is the same whether you're asking about money or relationships. It describes the house's energy as such — and doesn't depend on your question. So it's generated once and saved.
The first analysis is the most expensive. The system needs to generate energy texts for plan points that aren't yet in the cache.
The second, third, tenth are cheaper. The more texts have already been generated, the more points in the next plan will be found in the cache. You only pay for synthesis — assembling the final answer.
Follow-ups don't require a new plan or generation, but the context includes all the session's energy texts, the core personality, and the full conversation history. The longer the conversation and the more topics touched on — the more input tokens.
In essence, the first few questions "warm up" the chart, and after that the cost drops.
Free Tier
Upon registration you get for free:
- ◆One natal chart with full initialization (analysis of 12 houses + core personality)
- ◆Two questions with analysis — including, if you wish, a full personality analysis of the entire chart
- ◆Simple questions without astrology (greetings, "what can you do?") don't count
This costs me roughly €1.40 per user — even if they never come back. At this early stage, it's a deliberate choice: a person should try the product and see the quality of the analysis before deciding whether it's worth paying for.
The 2.0 Multiplier
The current sales multiplier is 2.0× the cost of Claude tokens. That means if the API calls for your analysis cost me €0.20 in tokens, you pay €0.40. The other expenses (Astrology API, Stripe, infrastructure, development) aren't baked into this amount directly — the multiplier covers them indirectly.
What this multiplier covers:
- ◆Fixed costs (Astrology API, infrastructure, Stripe fees)
- ◆Development and system maintenance
- ◆Losses from the free tier
- ◆My hours as developer and astrologer
The 2.0 multiplier isn't set in stone. It may change as the project grows (or doesn't). When that happens — I'll share it openly, just as I'm sharing now.
If you're curious about how the system is built from the inside and why caching makes each subsequent question cheaper — those are covered in separate posts.