Weigh your wifi: a two-device speed gauge
Internet speed tests measure your line to the world. This measures the hop that file transfers actually use — from one of your devices to another, across your own router.
Open this page on both devices. One shows a short room code, the other types it, and the pair links itself — then run the gauge from either side. Five seconds of random bytes go one way, five seconds the other; both screens show both readings.
Different networks? (not on the same wifi)
Leave this off to weigh your own wifi. Ticked, it uses a public STUN server to pair across the internet — which would gauge an internet path instead, and lets that server learn your IP.
Your room code
On the joining device, open filemonkey.org/wifi-speed, tap this device joins, and punch in this code —
warming up the link…
Type the code from the starting device
Whatever the starting device shows, punch it in and tap connect. Letters and digits both count; spaces won't trip it up.
connecting…
looking for the starting device…
the scales connect by themselves the moment the two devices meet.
Honest small print: this weighs your local network — router, walls, distance, band — not your internet line. It's the ceiling for any device-to-device transfer in your home, which makes it the right number to know before blaming a slow beam on this site.
Why gauge the hop between devices
Every "speed test" you've ever run measured the path from one device out to a server on the internet. But when you beam a file from your phone to your laptop, the internet isn't on the route at all — the bytes cross your room, phone → router → laptop. That leg has its own ceiling, set by wifi bands, walls, antennas and how far each device sits from the router, and it is routinely very different from your broadband number: a gigabit fiber line will not help two phones stuck on a congested 2.4 GHz band, and a modest 100 Mbps line says nothing about the 40 MB/s two 5 GHz devices can move locally.
The gauge pushes real random data (compression can't cheat) through the same direct channel our file beam uses, under the same flow control, so the number you see is the number your transfers get.
Reading the scales
- MB/s is megabytes per second — the file-transfer number. Mbps is megabits, the marketing number; divide by 8.
- The two directions often differ: phones throttle radio transmit power aggressively, and one device may sit closer to the router.
- Under ~2 MB/s on both directions usually means 2.4 GHz, long range, or a crowded channel. Try moving nearer the router and re-running.
Weighed it? Head back to the beaming counter and move the actual files — or check both copies match at the checksum desk.