Set a target and Solve. The calculator works backwards to the smallest change on each lever, then one tap applies it.
Net revenue (AOV, ex-tax)
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Cost of goods
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Variable selling cost
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– of which percentage fees
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– of which fixed fees
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Contribution margin (pre-refund)
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Refund leak
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True contribution margin
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Put this calculator on your own site, free
Two lines of code. It stays in sync, costs nothing, asks nothing.
If your audience would find this useful, host it. Paste the snippet below where you want it to appear. The tool runs from this site, so it updates itself; it adapts to your visitor's business model, solves backwards from a target, and gives them a "Copy for LLM" and "Copy my numbers" button so they can carry the work into their own AI, briefing it on the margin model and on your business too. It even co-brands itself: a small badge pairs your site's icon with mine, so it reads as a collaboration. No sign-up, no script bloat, no tracking of your visitors.
Paste the URL of the page you'll embed the tool on. We'll read its colours and fonts and show you what the calculator would look like in your brand.
Reading your site…
Extracted colours
Click an area below, then tap colours above to paint it. The area stays selected, so try a few quickly. The green (money kept) and red (leaks) are generated automatically so the chart always reads right.
Background
Text
Accent
Border
Fine-tune surfaces (cards, fields, buttons, active tab)
Cards
Fields
Buttons & tabs
Active tab
Pick a colour from the strip above
How the collaboration badge will appear:
×A tool from Christopher White Consulting, provided by Your website. The full playbook, The Money You Actually Keep, explains every stage.
<div data-cwc-tool="margin-calculator" data-cwc-title="Margin & Break-even Calculator by Christopher White Consulting" data-cwc-reserve-narrow="2200" data-cwc-reserve-wide="1320" style="min-height:1320px"></div>
<script src="https://christopherwhite.com.au/embed/loader.js" data-cwc-tool="margin-calculator" async></script>
Paste the two lines where you want the calculator to appear.
Use a real HTML / "embed code" block, not a rich-text field, so the <script> survives.
Publish. It loads instantly and auto-sizes its height; nothing to set, nothing to maintain.
Stuck? Paste the install guide into ChatGPT, Claude or Gemini and it'll walk you through your exact platform, or just point your AI at christopherwhite.com.au/embed/install.md.