CSS Design Calc
Screen pixel density (PPI) from resolution and diagonal, physical size, CSS viewport at a device pixel ratio, and image widths.
MediaLiveeip155:8453Exactvia cdp
CssPpiDprResponsive-images
Calls · 30d
1
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far.
$24.31
Verified settled volume
1,175 settlements proven x402 by their on-chain EIP-3009 marker.
$0.020
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-10-20 20:59Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xb531320805C5BED1D46AEaDcF4F008FDF172DBDaThe wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Provider
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
Live 402 challenge
Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.
{
"error": "Payment required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://css-design-calc.x402tookit.com/pixel-density",
"description": "Screen pixel density (PPI) from resolution and diagonal, physical size, CSS viewport at a device pixel ratio, and image widths.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"dpr": 1,
"widthPx": 2560,
"cssWidth": 400,
"heightPx": 1440,
"diagonalIn": 27
}
},
"output": {
"dpr": 1,
"ppi": 108.7855,
"asOf": "2026-10-11T14:32:44.713Z",
"source": "PPI = sqrt(w^2 + h^2) / diagonal; CSS reference pixel = 1/96 in; computed locally",
"reasons": [
"One CSS pixel spans 0.00919 in (0.2335 mm) on this screen at DPR 1; the CSS reference pixel is 1/96 in.",
"Bands: under 120 PPI standard, 120 to 220 high, above 220 very high."
],
"summary": "2560 x 1440 on a 27 inch screen is 108.79 PPI (23.53 x 13.24 in); 2560 x 1440 CSS px at DPR 1.",
"verdict": "STANDARD",
"widthMm": 597.727,
"degraded": false,
"heightMm": 336.221,
"ppiClass": "STANDARD",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"dotPitchMm": 0.23349,
"megapixels": 3.6864,
"notChecked": [
"the real device pixel ratio (browsers and OS scaling set it, not the panel)",
"non-square pixels and pentile subpixel layouts",
"…2 more"
],
"widthInches": 23.5325,
"heightInches": 13.2371,
"cssViewportWidth": 2560,
"cssViewportHeight": 1440,
"cssPixelPhysicalMm": 0.233487,
"imageWidthsForCssWidth": {
"1x": 400,
"2x": 800,
"3x": 1200,
"1.5x": 600,
"cssWidth": 400,
"atThisDpr": 400
},
"idealDprForReferencePixel": 1.1332
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"feePayer": "BFK9TLC3edb13K6v4YyH3DwPb5DSUpkWvb7XnqCL9b4F"
},
"payTo": "DUPiupXtuox38dcGoXUKer5mAydCzmaHjrbQ66qeEm8s",
"scheme": "exact",
"network": "solana",
"mimeType": "application/json",
"resource": "https://css-design-calc.x402tookit.com/pixel-density",
"description": "Screen pixel density (PPI) from resolution and diagonal, physical size, CSS viewport at a device pixel ratio, and image widths.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"dpr": 1,
"widthPx": 2560,
"cssWidth": 400,
"heightPx": 1440,
"diagonalIn": 27
}
},
"output": {
"dpr": 1,
"ppi": 108.7855,
"asOf": "2026-10-11T14:32:44.713Z",
"source": "PPI = sqrt(w^2 + h^2) / diagonal; CSS reference pixel = 1/96 in; computed locally",
"reasons": [
"One CSS pixel spans 0.00919 in (0.2335 mm) on this screen at DPR 1; the CSS reference pixel is 1/96 in.",
"Bands: under 120 PPI standard, 120 to 220 high, above 220 very high."
],
"summary": "2560 x 1440 on a 27 inch screen is 108.79 PPI (23.53 x 13.24 in); 2560 x 1440 CSS px at DPR 1.",
"verdict": "STANDARD",
"widthMm": 597.727,
"degraded": false,
"heightMm": 336.221,
"ppiClass": "STANDARD",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"dotPitchMm": 0.23349,
"megapixels": 3.6864,
"notChecked": [
"the real device pixel ratio (browsers and OS scaling set it, not the panel)",
"non-square pixels and pentile subpixel layouts",
"…2 more"
],
"widthInches": 23.5325,
"heightInches": 13.2371,
"cssViewportWidth": 2560,
"cssViewportHeight": 1440,
"cssPixelPhysicalMm": 0.233487,
"imageWidthsForCssWidth": {
"1x": 400,
"2x": 800,
"3x": 1200,
"1.5x": 600,
"cssWidth": 400,
"atThisDpr": 400
},
"idealDprForReferencePixel": 1.1332
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
},
{
"asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"scheme": "exact",
"network": "polygon",
"mimeType": "application/json",
"resource": "https://css-design-calc.x402tookit.com/pixel-density",
"description": "Screen pixel density (PPI) from resolution and diagonal, physical size, CSS viewport at a device pixel ratio, and image widths.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"dpr": 1,
"widthPx": 2560,
"cssWidth": 400,
"heightPx": 1440,
"diagonalIn": 27
}
},
"output": {
"dpr": 1,
"ppi": 108.7855,
"asOf": "2026-10-11T14:32:44.713Z",
"source": "PPI = sqrt(w^2 + h^2) / diagonal; CSS reference pixel = 1/96 in; computed locally",
"reasons": [
"One CSS pixel spans 0.00919 in (0.2335 mm) on this screen at DPR 1; the CSS reference pixel is 1/96 in.",
"Bands: under 120 PPI standard, 120 to 220 high, above 220 very high."
],
"summary": "2560 x 1440 on a 27 inch screen is 108.79 PPI (23.53 x 13.24 in); 2560 x 1440 CSS px at DPR 1.",
"verdict": "STANDARD",
"widthMm": 597.727,
"degraded": false,
"heightMm": 336.221,
"ppiClass": "STANDARD",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"dotPitchMm": 0.23349,
"megapixels": 3.6864,
"notChecked": [
"the real device pixel ratio (browsers and OS scaling set it, not the panel)",
"non-square pixels and pentile subpixel layouts",
"…2 more"
],
"widthInches": 23.5325,
"heightInches": 13.2371,
"cssViewportWidth": 2560,
"cssViewportHeight": 1440,
"cssPixelPhysicalMm": 0.233487,
"imageWidthsForCssWidth": {
"1x": 400,
"2x": 800,
"3x": 1200,
"1.5x": 600,
"cssWidth": 400,
"atThisDpr": 400
},
"idealDprForReferencePixel": 1.1332
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1,
"alsoAvailable": {
"llms": "https://css-design-calc.x402tookit.com/llms.txt",
"catalog": "https://css-design-calc.x402tookit.com/catalog",
"message": "CSS Design Calc has 12 pay-per-call endpoints (CSS and layout maths for agents: unit conversion, fluid clamp(), type scales, aspect ratios, grids, specificity and readability.), from $0.02 a call. See the full menu and send your agents our way.",
"openapi": "https://css-design-calc.x402tookit.com/openapi.json",
"related": [
{
"url": "https://css-design-calc.x402tookit.com/target-size",
"path": "/target-size",
"what": "Check a click or touch target against WCAG 2.2 target size (24 px AA, 44 px AAA) includin…",
"price": "$0.02"
},
{
"url": "https://css-design-calc.x402tookit.com/type-scale",
"path": "/type-scale",
"what": "Modular type scale: sizes in px and rem for steps below and above a base size, by named r…",
"price": "$0.02"
},
{
"url": "https://css-design-calc.x402tookit.com/vertical-rhythm",
"path": "/vertical-rhythm",
"what": "Snap line-heights for font sizes to a baseline grid: baseline unit, lines per element, un…",
"price": "$0.02"
}
]
}
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
0.02USDC≈ $0.02 USD
on Base · exact scheme
Pay 0.02 USDC on Base to 0xb531…2DBDa. The signed payment is good for 5 minutes.
- Paid to
- 0xb531…2DBDa
- USD Coin contract
- 0x8335…02913
- Payment window
- 5 minutes
- As published
- 20000 smallest units
20000units
on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- DUPiup…eEm8s
- Token contract
- EPjFWd…TDt1v
- Payment window
- 5 minutes
20000units
on Polygon · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0x3c49…c3359
- Payment window
- 5 minutes
20000units
on Arbitrum · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0xaf88…e5831
- Payment window
- 5 minutes
The catalog’s raw entry
[
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 300
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"feePayer": "D6ZhtNQ5nT9ZnTHUbqXZsTx5MH2rPFiBBggX4hY1WePM"
},
"payTo": "DUPiupXtuox38dcGoXUKer5mAydCzmaHjrbQ66qeEm8s",
"amount": "20000",
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"maxTimeoutSeconds": 300
},
{
"asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:137",
"maxTimeoutSeconds": 300
},
{
"asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:42161",
"maxTimeoutSeconds": 300
}
]Extensions
{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"dpr": 1,
"widthPx": 2560,
"cssWidth": 400,
"heightPx": 1440,
"diagonalIn": 27
}
},
"output": {
"type": "json",
"example": {
"dpr": 1,
"ppi": 108.7855,
"asOf": "2026-10-11T14:32:44.713Z",
"source": "PPI = sqrt(w^2 + h^2) / diagonal; CSS reference pixel = 1/96 in; computed locally",
"reasons": [
"One CSS pixel spans 0.00919 in (0.2335 mm) on this screen at DPR 1; the CSS reference pixel is 1/96 in.",
"Bands: under 120 PPI standard, 120 to 220 high, above 220 very high."
],
"summary": "2560 x 1440 on a 27 inch screen is 108.79 PPI (23.53 x 13.24 in); 2560 x 1440 CSS px at DPR 1.",
"verdict": "STANDARD",
"widthMm": 597.727,
"degraded": false,
"heightMm": 336.221,
"ppiClass": "STANDARD",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"dotPitchMm": 0.23349,
"megapixels": 3.6864,
"notChecked": [
"the real device pixel ratio (browsers and OS scaling set it, not the panel)",
"non-square pixels and pentile subpixel layouts",
"…2 more"
],
"widthInches": 23.5325,
"heightInches": 13.2371,
"cssViewportWidth": 2560,
"cssViewportHeight": 1440,
"cssPixelPhysicalMm": 0.233487,
"imageWidthsForCssWidth": {
"1x": 400,
"2x": 800,
"3x": 1200,
"1.5x": 600,
"cssWidth": 400,
"atThisDpr": 400
},
"idealDprForReferencePixel": 1.1332
}
}
},
"schema": {
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"required": [
"input"
],
"properties": {
"input": {
"type": "object",
"required": [
"type",
"method"
],
"properties": {
"type": {
"type": "string",
"const": "http"
},
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"type": "object",
"required": [
"widthPx",
"heightPx",
"diagonalIn"
],
"properties": {
"dpr": {
"type": "number",
"description": "Device pixel ratio the browser reports (default 1)"
},
"widthPx": {
"type": "number",
"description": "Horizontal resolution in physical pixels"
},
"cssWidth": {
"type": "number",
"description": "A CSS width in px to compute image pixel widths for (default 100)"
},
"heightPx": {
"type": "number",
"description": "Vertical resolution in physical pixels"
},
"diagonalIn": {
"type": "number",
"description": "Screen diagonal in inches"
}
}
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string"
},
"example": {
"type": "object",
"properties": {
"dpr": {
"type": [
"null",
"number"
]
},
"ppi": {
"type": [
"null",
"number"
]
},
"asOf": {
"type": [
"null",
"string"
]
},
"source": {
"type": [
"null",
"string"
]
},
"reasons": {
"type": [
"array",
"null"
],
"items": {
"type": "string"
}
},
"summary": {
"type": [
"null",
"string"
]
},
"verdict": {
"type": [
"null",
"string"
]
},
"widthMm": {
"type": [
"null",
"number"
]
},
"degraded": {
"type": [
"boolean",
"null"
]
},
"heightMm": {
"type": [
"null",
"number"
]
},
"ppiClass": {
"type": [
"null",
"string"
]
},
"disclaimer": {
"type": [
"null",
"string"
]
},
"dotPitchMm": {
"type": [
"null",
"number"
]
},
"megapixels": {
"type": [
"null",
"number"
]
},
"notChecked": {
"type": [
"array",
"null"
],
"items": {
"type": "string"
}
},
"widthInches": {
"type": [
"null",
"number"
]
},
"heightInches": {
"type": [
"null",
"number"
]
},
"cssViewportWidth": {
"type": [
"null",
"number"
]
},
"cssViewportHeight": {
"type": [
"null",
"number"
]
},
"cssPixelPhysicalMm": {
"type": [
"null",
"number"
]
},
"imageWidthsForCssWidth": {
"type": [
"null",
"object"
],
"properties": {
"1x": {
"type": [
"null",
"number"
]
},
"2x": {
"type": [
"null",
"number"
]
},
"3x": {
"type": [
"null",
"number"
]
},
"1.5x": {
"type": [
"null",
"number"
]
},
"cssWidth": {
"type": [
"null",
"number"
]
},
"atThisDpr": {
"type": [
"null",
"number"
]
}
}
},
"idealDprForReferencePixel": {
"type": [
"null",
"number"
]
}
}
}
}
}
}
}
}
}Provenance
- Seen in the source catalog
- 2026-10-20 20:59Z
- Last indexed by Roundhouse
- 2026-10-22 12:40Z
- Last enriched (probe, favicon, geo)
- 2026-10-20 22:15Z
- x402 version
- 2
- Max timeout
- 300s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service CSS Design Calc and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=CSS%20Design%20Calc' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://css-design-calc.x402tookit.com/pixel-density, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Either pay over x402 (mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402), or ask me for an organization key, which I create at https://roundhouseai.io/dashboard/connections. If you have neither, ask before going further. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.