Stop guessing. Buy the right length once.
Answer four quick questions — no tape measure needed — and get the length to order, with slack already included.
Pick the closest match. This sets the cable type and a starting distance.
Type in what you know. If you're not sure, use the body-measurement helper below — no tape measure needed.
Enter your height and the tool works out your reach, stride and span. Then pace out the run and count.
Cable that follows walls is always longer than the straight-line distance.
Spare cable for reaching the port, dressing it behind furniture, and moving gear later.
Click a question to open it.
A passive HDMI cable gets unreliable past roughly 25 ft at 4K60. Below that, a well-made passive cable is fine and paying more buys nothing. Above it, the fix is not a longer passive cable but a different product: an active or fiber-optic HDMI cable, which regenerates the signal and runs to 50 ft, 100 ft and beyond. Fiber-optic HDMI is directional, so check which end goes at the source.
Ethernet is specified to 328 ft (100 m) per run, and that figure includes patch cables at both ends, not just the long middle section. Past that, adding a longer cable does not help; you need a switch or an extender partway along the run. Cat6 handles gigabit comfortably over that full distance.
Around 2 to 3 ft at each end is the usual allowance. That covers reaching the actual port rather than the edge of the device, dressing the cable behind furniture, and pulling gear out from a wall to work on it later. Skipping slack is the single most common reason a cable measured correctly still turns out to be too short.
Yes, and it is usually a lot more than people expect. A straight-line measurement between two devices is the shortest possible path and almost never the path the cable takes. Following walls, going around door frames, dropping down to a floor and back up again, and allowing a bend radius at each corner can easily add half again to the straight-line figure.
Passive DisplayPort tops out around 15 ft at high refresh rates, and passive USB-C loses high-speed data past roughly 10 ft. Both have active versions that go further. USB-C in particular is not one cable type: a cable that carries power fine may not carry video or 10 Gbps data at length, so check the spec rather than the connector shape.
For runs under about 50 ft, 16 AWG is generally fine and 14 AWG is comfortable. Past roughly 100 ft, step up to 12 AWG to limit voltage drop, and for long Speakon runs feeding a powered PA, 10 AWG. Thin wire on a long run wastes amplifier power as heat in the cable rather than sound at the speaker.
Balanced XLR runs happily to 200 ft and beyond with no meaningful signal loss, which is why balanced audio is the standard for live sound. This is one of the few cable types where length is rarely the limiting factor. For very long runs, a heavier gauge cable is more about mechanical durability than signal quality.
Mildly, and much less bad than buying one that is too short. Excess cable is untidy, has to be coiled somewhere, and on very long analog runs adds a little loss. A cable that is too short is useless and has to be returned. Where the answer sits between two stocked lengths, take the longer one.
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