Envelope Fit

{
  "asOf": "2026-10-12T01:48:14.146Z",
  "clearanceInches": 0.125,
  "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.",
  "envelopesChecked": 15,
  "fits": [
    {
      "envelope": "a7",
      "marginPerSideInches": 0.125,
      "sizeInches": [
        5.25,
        7.25
      ],
      "sizeMm": [
        133.4,
        184.1
      ]
    },
    {
      "envelope": "a9",
      "marginPerSideInches": 0.375,
      "sizeInches": [
        5.75,
        8.75
      ],
      "sizeMm": [
        146,
        222.3
      ]
    }
  ],
  "notChecked": [
    "thickness of a bulky piece or insert",
    "postal size and weight rules (check your post office)",
    "…1 more"
  ],
  "pieceInches": [
    5,
    7
  ],
  "reasons": [
    "Both orientations of the piece are tried; a larger gap per side means a looser fit."
  ],
  "snuggestFit": "a7",
  "source": "computed locally (envelope sizes, both orientations)",
  "summary": "7 envelope(s) hold it; snuggest: a7 (0.125 in a side).",
  "verdict": "FITS"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://paper-print-calc.x402tookit.com/envelope-fit?height=7&unit=in&width=5'

# 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://paper-print-calc.x402tookit.com/envelope-fit?height=7&unit=in&width=5' \
  | 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%2Fpaper-print-calc.x402tookit.com%2Fenvelope-fit
const res = await pay("https://paper-print-calc.x402tookit.com/envelope-fit?height=7&unit=in&width=5");
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://paper-print-calc.x402tookit.com/envelope-fit?height=7&unit=in&width=5")
    print(res.status_code, res.text)