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CSS Design Calc – Box Model Size Calculator
x402
CSS Design Calc – Box Model Size Calculator is a paid API for AI agents from css-design-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).
Calculates all CSS box model dimensions (content, padding, border, and margin boxes) from a given width and height under content-box or border-box sizing
Price / call$0.02
Success—
StatusUnknown
How this service works
CSS box model sizes: content, padding, border and margin boxes from a width and height under content-box or border-box.
Output
Returns all computed CSS box model dimensions as numbers: contentWidth, contentHeight, paddingBoxWidth, paddingBoxHeight, borderBoxWidth, borderBoxHeight, marginBoxWidth, marginBoxHeight, plus widthToSetForBorderBox and widthToSetForContentBox — letting you know what CSS width value to specify for either sizing model to achieve your desired layout.
Example use cases
Verify actual rendered element size
“I have a CSS element set to 480px wide in border-box mode with 20px padding and 1px border on each side — what will its content area and total margin box dimensions be?”
Convert content-box to border-box width
“If I want a 600px content area with 24px padding and 2px border on each side, what width do I need to set if I switch to border-box sizing?”
Debug layout with margin and padding layers
“Can you break down all the box model layers for a 250px square element using content-box sizing, with 12px padding, 3px border, and 16px margin on each side? I need content, padding, border, and margin box sizes.”
Technical details
Endpoint
GEThttps://css-design-calc.x402tookit.com/box-size?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to compute all CSS box model layers programmatically — especially when switching between content-box and border-box sizing models, debugging layout size mismatches, or automating design calculations that require knowing the precise rendered size of elements including padding, border, and margin contributions.
Side effects
- Missing required 'width' parameter returns a validation error
- Non-numeric values for width, height, padding, border, or margin cause a bad request error
- Invalid boxSizing enum value (anything other than 'content-box' or 'border-box') returns an error
- Negative dimension values may produce unexpected or invalid results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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