Screen Mirroring Bandwidth Checker

Why mirroring stutters on "fast" Wi-Fi

Screen mirroring feels like it should be easy — your phone and TV are in the same room, after all. But mirroring sends a live, constantly changing video stream from your phone to the display, and that stream rides your Wi-Fi in real time with no meaningful buffer. A 300 Mbps internet plan means nothing here; what matters is the actual wireless link between your phone and router, which halves with every wall and drops sharply with distance. Add a microwave, a neighbor's network on the same channel, or a phone that quietly dropped to the 2.4 GHz band, and your "fast" connection delivers a fraction of its headline speed exactly when the video needs it most.

How the checker does the math

It starts with a base bitrate for your mirror quality: about 6 Mbps for 720p, 12 Mbps for 1080p, and 25 Mbps for 4K. That base is multiplied by a content factor, because what you mirror matters — mostly-still slides compress easily (0.6x), video runs at full rate (1.0x), and fast-motion gaming needs extra headroom (1.4x). Then it adds 25% protocol overhead for Wi-Fi framing and retransmissions. The result is the sustained throughput your mirror truly needs, which the tool compares against your measured Wi-Fi speed to compute headroom and a safety ratio, plus the best quality your connection can carry for video content.

Worked example

Mirror 1080p video over a measured 150 Mbps Wi-Fi link. Need is 12 x 1.0 x 1.25 = 15.0 Mbps. Headroom is 150 − 15 = 135.0 Mbps, a 10.00x safety ratio — comfortably in the Smooth band, and the same link could even carry 4K video (needs 31.25 Mbps). Now try 4K gaming on a 40 Mbps link: need is 25 x 1.4 x 1.25 = 43.75 Mbps, which exceeds the link — headroom −3.8 Mbps, ratio 0.91x, verdict Will stutter. Dropping to 1080p gaming needs only 21.0 Mbps, which the 40 Mbps link handles with room to spare.

Tips for smooth mirroring

Put both devices on the 5 GHz band — it is faster and far less crowded than 2.4 GHz. Keep the phone within a few meters of the router with line of sight; every wall between them costs real throughput. Close background apps on the phone, since uploads and cloud syncs steal airtime mid-mirror. If your TV dongle supports it, update its firmware — manufacturers regularly improve streaming stability. And for competitive gaming, nothing beats a wired HDMI adapter: zero lag, zero stutter, zero math required.