Box Size

{
  "asOf": "2026-10-11T14:32:42.869Z",
  "borderBoxHeight": 244,
  "borderBoxWidth": 344,
  "boxSizing": "content-box",
  "contentHeight": 200,
  "contentWidth": 300,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "marginBoxHeight": 264,
  "marginBoxWidth": 364,
  "notChecked": [
    "margin collapsing between siblings and parents",
    "min-width, max-width and flex or grid sizing",
    "…1 more"
  ],
  "paddingBoxHeight": 240,
  "paddingBoxWidth": 340,
  "reasons": [
    "width and height set the CONTENT box; padding and border are added outside it."
  ],
  "source": "CSS Box Model Level 3 (width applies to the content box or the border box depending on box-sizing), computed locally",
  "summary": "Under content-box, a 300 x 200 box has content 300 x 200, border box 344 x 244, margin box 364 x 264.",
  "verdict": "COMPUTED",
  "widthToSetForBorderBox": 344,
  "widthToSetForContentBox": 300
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://css-design-calc.x402tookit.com/box-size?border=2&boxSizing=content-box&height=200&margin=10&padding=20&width=300'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://css-design-calc.x402tookit.com/box-size?border=2&boxSizing=content-box&height=200&margin=10&padding=20&width=300' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fcss-design-calc.x402tookit.com%2Fbox-size
const res = await pay("https://css-design-calc.x402tookit.com/box-size?border=2&boxSizing=content-box&height=200&margin=10&padding=20&width=300");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://css-design-calc.x402tookit.com/box-size?border=2&boxSizing=content-box&height=200&margin=10&padding=20&width=300")
    print(res.status_code, res.text)