Propagation Delay

{
  "asOf": "2026-10-11T14:45:32.093Z",
  "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.",
  "distanceKm": 5570.2299,
  "distanceSource": "great circle",
  "linkMbps": null,
  "medium": "fiber",
  "microsecondsPerKm": 4.89672,
  "notChecked": [
    "real cable routes, which are longer than the great circle (submarine and terrestrial paths add 30% to 100% or more)",
    "equipment, queueing, routing and processing delay, which usually exceed propagation delay on short paths",
    "…3 more"
  ],
  "oneWayMs": 27.275861,
  "packetBytes": 1500,
  "pathKm": 5570.2299,
  "percentOfLightSpeed": 68.1199,
  "reasons": [
    "Speed in optical fibre (group index about 1.468): c / 1.468 = 204218.3 km/s, or 4.897 microseconds per km.",
    "This is the physical lower bound: real round-trip times are higher because of detours, queueing and equipment."
  ],
  "refractiveIndex": 1.468,
  "roundTripMs": 54.551722,
  "routeFactor": 1,
  "serializationMs": null,
  "source": "Propagation speed c / n with c = 299,792.458 km/s; great-circle distance on a 6371.0088 km sphere, computed locally",
  "speedKmPerSecond": 204218.296,
  "summary": "5570.2 km of fiber: 27.276 ms one way, 54.552 ms round trip at 204218 km/s (68.1% of c).",
  "totalOneWayMs": 27.275861,
  "vacuumOneWayMs": 18.580287,
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://network-calc.x402tookit.com/propagation-delay?lat1=40.7128&lat2=51.5074&lon1=-74.006&lon2=-0.1278&medium=fiber&routeFactor=1'

# 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://network-calc.x402tookit.com/propagation-delay?lat1=40.7128&lat2=51.5074&lon1=-74.006&lon2=-0.1278&medium=fiber&routeFactor=1' \
  | 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%2Fnetwork-calc.x402tookit.com%2Fpropagation-delay
const res = await pay("https://network-calc.x402tookit.com/propagation-delay?lat1=40.7128&lat2=51.5074&lon1=-74.006&lon2=-0.1278&medium=fiber&routeFactor=1");
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://network-calc.x402tookit.com/propagation-delay?lat1=40.7128&lat2=51.5074&lon1=-74.006&lon2=-0.1278&medium=fiber&routeFactor=1")
    print(res.status_code, res.text)