Unit Economics Tool

Hemrock’s financial models are available to everyone. All donations are appreciated to support their continue development and support.

This model is open source under the Apache License 2.0. You can use it, modify it, redistribute it, and incorporate it into commercial work subject to the license. Apache 2.0 license

What you'll do with it

Forecast the lifetime value of one customer. Plug in pricing, churn, contract length, billing cycle, and cost of sales, and the model returns LTV, contribution margin, payback period, and breakeven on acquisition cost.

Built for the question that comes up at every stage: do my unit economics actually work? Pressure-test pricing, decide whether to spend on acquisition, sanity-check a SaaS or transactional business before scaling.

What's inside

• Recurring and transactional revenue mechanics, side by side
• Churn, customer lifetime, and contract length drivers
• LTV, contribution margin, payback period, breakeven on CAC
• Clean, documented formulas, with every cell open

Edit with AI

Every cell open. Inputs in blue, formulas in black, rows documented. Built so you and your AI can edit without breaking it.

1. Context primer. Paste it into Claude or ChatGPT before you make a change.
2. Prompt guide. Ready-made prompts for setup and customization.
3. Hemrock Skill. A drop-in Claude Agent Skill that loads this model's sheet map, prompts, and checks into any Claude Project. Free, with no connector to set up.
4. MCP server. On ChatGPT, Cursor, or another tool? The MCP server feeds the same context to any AI that speaks MCP.
5. Verify before you trust. The sanity-check prompts catch wrong references and confused metrics.

When to use this vs. other tools

Focused tool for unit economics only. If you need expenses, hiring, financial statements, and cap table on top, use the Standard Financial Model. If you're modeling ecommerce specifically, try the Ecommerce Forecasting Tool for cohort-based new-vs-repeat customer logic.

Common questions

Why use this when AI can calculate LTV and CAC for me?
AI will hand you an LTV number. The harder question is whether the model behind it treats churn, contract length, and cost of sales correctly, which is exactly where it tends to be plausibly wrong. This is a single sheet where that math is already right, so you can trust the answer or see precisely why you don't.

Is it too simple to be useful?
It's one sheet on purpose. Unit economics is the question you answer before building a five-year forecast, not after. When you're ready for the full picture, move up to the Standard Financial Model.

Excel or Google Sheets?
Both. All formulas open.

Documentation

• Cohort modeling
• Revenue modeling