AV Cable Length Calculator
Free cable length calculator for AV integrators, installers and designers.
Work out how much cable to order for one run, a whole room or a speaker line. Every run is checked against its distance limit and the AVIXA cabling verification items.
- Choose what to calculate.
- Drag the blue handles on the drawing, or type the distances.
- Read the results, then share or download them.
Project settings
Choose what to calculate
Draw or enter your cable run
Free Cable Length Calculator for AV Installs
The distance on the floor plan is never the length of cable you need. Cable climbs walls, drops through ceilings, sags between J-hooks, bends around obstacles and needs slack at both ends. Order from the plan measurement and you'll come up short on install day.
This AV cable length calculator adds all of that up. Use it as a cable run calculator for a single run, build a cable schedule for a whole room before the cable pull, or use the speaker wire gauge calculator to check power loss on a speaker line. Every run is checked against the practical distance limit for its cable type, so you find out an HDMI run is too long before it's in the wall.
Why Cable Length Matters in AV
Getting length wrong costs you in two ways. Too short and you're splicing, re-pulling or making a second trip. Too long for the signal and the system fails in ways that are hard to diagnose: flickering video, dropped USB devices, audio that's quieter than the design.
Signal distance limits
Every cable type has a point where the signal stops being reliable. Passive HDMI 2.0 tops out around 10 m (33 ft) at 4K60. USB 3 gives up at 3 m (10 ft). Cat6 is good for 100 m (328 ft). Past those limits you need an extender, an active cable or fiber, and that changes your BOM and your budget.
Speaker wire loss
Speaker cable doesn't have a hard limit. Instead it wastes power as heat. On an 8Ω speaker, 20 m (66 ft) of 16 AWG loses about 12% of the amplifier's power. Move to 14 AWG and the loss drops to under 8%. On a 70V line the same wire can run hundreds of meters.
Ordering and budget
Bulk cable comes in fixed boxes and spools. Knowing your total length tells you whether one 1000 ft box of Cat6 covers the room or whether you need two, before the order goes in.
How to Use the Cable Length Calculator
- Choose what to calculate. Single cable for one run, Whole room for every cable in a project, Speaker wire to check gauge, power loss and maximum length.
- Draw or enter the run. Drag the handles on the side-view canvas to set device heights, the cable pathway, the distance and the service loop, or type the measurements into the fields. Both stay in sync.
- Name the ends and set slack. Enter From and To so the schedule matches your drawings, a service loop per end, rack travel for pull-out or swing racks, and a waste allowance.
- Read the results. Installed path, order length, stock size, the AVIXA verification checks for each run and a left/right bundle plan. Whole room mode draws every cable on one drawing, with the cable list beside it. Click Edit on any cable to change it, and show or hide cables to declutter the view. Share a public link, download a PDF report, copy the cable schedule, or sign up to draw it in X-DRAW.
Cable Length Formula
H × routing + rise + drop + 2 × loop + rack travel
Path × (1 + waste %)
Total order ÷ box length, rounded up
R = 2 × length × Ω per meter
1 − (Z ÷ (Z + R))²
Z = V² ÷ total tap watts
How to calculate cable length for a run
Multiply the horizontal distance by a routing factor (1.00 direct, 1.10 J-hooks or tray, 1.15 raceway or floor, 1.20 conduit). Add the vertical rise at the source and the drop at the destination. Add a service loop at each end, plus rack travel if the source is a pull-out or swing rack. Multiply by one plus your waste allowance to get the length to order.
How to calculate speaker wire loss
Speaker current travels out and back, so wire resistance is twice the run length times the resistance per meter of the gauge. Compare it to the speaker's impedance: the power that reaches the speaker is (Z ÷ (Z + R))². For 70V and 100V lines, the impedance the amp sees is the line voltage squared divided by the total tap watts.
Maximum Cable Length Chart: HDMI, Cat6, USB and HDBaseT
Use this chart to check the HDMI cable max length, Cat6 max length, USB cable max length and DisplayPort max length before you design a run. These are practical distances for reliable signal. Real results depend on cable grade, source device and extender model.
| Cable type | Max length | Past the limit, use |
|---|---|---|
| HDMI 2.0 passive (18 Gbps) | 10 m (33 ft) | HDBaseT extender or active optical HDMI |
| HDMI 2.1 passive (48 Gbps) | 5 m (16 ft) | Active optical HDMI 2.1 |
| HDMI active optical (AOC) | 100 m (328 ft) | Fiber extender pair |
| HDBaseT over Cat6A | 100 m (328 ft) | Long-reach extender or fiber. Many 4K60 4:4:4 extenders are rated for 40 m. |
| Cat6 Ethernet, Dante, AV-over-IP | 100 m (328 ft) | A switch mid-run, or fiber |
| USB 2.0 passive | 5 m (16 ft) | USB-over-Cat extender or active USB |
| USB 3.x passive | 3 m (10 ft) | Active optical USB 3 or USB 3 extender |
| DisplayPort passive | 3 m (10 ft) | DisplayPort AOC or HDBaseT |
| 12G-SDI coax | 70 m (230 ft) | Reclocker or SDI over fiber |
| 3G-SDI coax | 100 m (328 ft) | Reclocking distribution amp |
| Balanced analog audio | 100 m (328 ft) | Dante or another audio network |
| RS-232 control | 15 m (50 ft) | RS-232 over Cat extender, or IP control |
| Fiber OM3 multimode (10G) | 300 m (984 ft) | OS2 single-mode fiber |
How long can an HDMI cable be?
For reliable 4K60, the max HDMI cable length is about 10 m (33 ft) for a passive HDMI 2.0 cable and 5 m (16 ft) for passive HDMI 2.1 at 48 Gbps. For longer runs, use an active optical HDMI cable, which reaches 100 m (328 ft), or an HDBaseT extender over Cat6A.
What is the Cat6 max length?
The Cat6 max length is 100 m (328 ft) for the full channel, including patch cords at both ends. The same Ethernet cable max length applies to Dante, AV-over-IP and HDBaseT links. Some 4K HDBaseT extenders are rated for 40 m only, so check the extender's spec.
What is the USB cable max length?
Passive USB 2.0 cables are limited to 5 m (16 ft) and passive USB 3.x cables to 3 m (10 ft). Conference cameras and soundbars often sit farther than that from the room PC, so plan a USB-over-Cat extender or an active optical USB cable. Passive DisplayPort has a similar 3 m (10 ft) practical limit.
Speaker Wire Gauge Chart
This speaker wire gauge chart shows the longest one-way run for each speaker cable gauge before you lose 0.5 dB (11%) of the amplifier's power. The 70V columns assume the total tap watts shown on the line.
| Gauge | 8Ω | 4Ω | 70V, 60 W | 70V, 120 W |
|---|---|---|---|---|
| 12 AWG | 46 m (151 ft) | 23 m (76 ft) | 470 m (1,543 ft) | 235 m (771 ft) |
| 14 AWG | 29 m (95 ft) | 14.5 m (48 ft) | 296 m (971 ft) | 148 m (485 ft) |
| 16 AWG | 18 m (60 ft) | 9 m (30 ft) | 186 m (609 ft) | 93 m (304 ft) |
| 18 AWG | 11 m (37 ft) | 5.7 m (19 ft) | 117 m (383 ft) | 58 m (191 ft) |
What gauge speaker wire do I need?
Find your speaker impedance and run length in the chart and pick the first gauge that covers it. For most 8Ω runs in a room, 14 AWG or 16 AWG is enough. Long low-impedance runs need 12 AWG, and 70V or 100V lines can use 16 or 18 AWG over much longer distances. For an exact answer, use the Speaker wire mode in the calculator above.
How to Calculate Cable for a Conference Room
Here's the conference room loaded in Room Schedule mode, worked out by hand with 10% waste:
| Run | Cable | Plan distance | Installed path | Order | Check |
|---|---|---|---|---|---|
| Rack to display | HDBaseT Cat6A | 16 m | 24.2 m | 26.6 m | Within limit |
| Table box to display | HDMI 2.0 | 7.5 m | 11.2 m | 12.3 m | Over 10 m limit |
| Ceiling mic to DSP | Cat6 (Dante) | 21 m | 28.4 m | 31.2 m | Within limit |
| Amp to ceiling speakers | 16 AWG, 70V | 24 m | 30.7 m | 33.8 m | 2% loss |
| Camera to room PC | USB 3.x | 3.5 m | 4.9 m | 5.4 m | Over 3 m limit |
| Room | 5 runs | 72 m | 99.4 m | 109.4 m | 2 flags |
The plan shows 72 m of cable. The room actually needs 109 m, about 50% more. Two runs also fail their checks. The table-box HDMI run looked short at 7.5 m, but the floor box, the wall climb and slack push it past 10 m. The USB camera is in the same spot. Both need an extender or an active cable, and that's equipment that wasn't in the original quote.
Why vertical distance adds up
In a room with a 2.7 m (9 ft) ceiling, a run from a floor-level rack to a ceiling device and back down to a wall-mounted display can add 4 m or more of pure vertical. On short runs that's often more than the horizontal distance.
Patch cables vs bulk cable
HDMI, USB and DisplayPort usually come as fixed-length patch cables, so the calculator rounds each run up to the next stock length. Cat6, speaker wire, coax and audio cable are pulled from bulk boxes, so the calculator totals them and tells you how many boxes to buy.
How the Calculator Follows AVIXA Verification
ANSI/InfoComm 10:2013 and its companion, the AVIXA (formerly InfoComm) Audiovisual Systems Performance Verification Guide, list the items an integrator checks before handing a system over. Most cabling items are checked on site, but several are decided when you plan lengths. The calculator builds those into every run so the cable you order can pass verification.
| Item | What AVIXA verifies | What the calculator does |
|---|---|---|
| CABL-105 | Every cable carries a unique, machine-printed label at both ends that matches the cable schedule. | Gives each run a unique cable ID with From and To, and copies a schedule you can label from. |
| CABL-115 | Cabling is the correct type and its routing and distance meet the manufacturer's spec. HDBaseT and fiber links should be performance-tested. | Checks each run against its cable type's distance limit and flags HDBaseT and fiber links for testing. |
| CABL-116 | There is enough cable to move a device to a serviceable spot and redo terminations. | Adds a service loop at each end and flags any run without one. |
| CABL-110 | Bulk cable is trimmed to length with a neat service loop, there are no splices, and pull-out or swing racks have enough length to move their full range. | Adds rack travel to the length and flags runs longer than one box or spool, which would need a splice. |
| CABL-100 | Cables stay within the minimum bend radius from the manufacturer's data sheet, including in conduit and pull boxes. | Adds a conduit routing factor and reminds you to size conduit and pull boxes from the data sheet. |
| CABL-106 / 109 | Cables are bundled by signal type, at least 100 mm (4 in) apart in the rack, and in separate conduit or partitioned raceway outside it. | Sorts runs into left-side and right-side rack bundles and warns when both groups share conduit. |
| AP-124 / AP-111 | Each loudspeaker line measures at or above its calculated impedance, which also confirms 70V/100V transformer taps. | Calculates the expected line impedance for every speaker run so you have the figure to test against. |
The 0.5 dB (11%) speaker loss target and the cable distance limits are common design practice and manufacturer guidance, not AVIXA verification metrics. Your project documentation and the manufacturer's spec always take priority.
Cabling Mistakes That Cost Integrators Time
Ordering from the floor plan
Plan distances leave out every rise, drop and turn. Add them, or the last runs in the project come up short.
No service loop
Without slack at the rack and the device, you can't re-terminate or move equipment without pulling new cable, and the run fails AVIXA CABL-116.
Passive HDMI on long runs
An HDMI run that works at 1080p can fail at 4K60. Anything near the limit should go over HDBaseT or an active cable from the start.
Thin speaker wire on low-impedance runs
18 AWG on an 8Ω speaker past 11 m wastes amplifier power. Go heavier, or move the zone to a 70V line.
Splicing a short run
A run longer than the box gets spliced to make it fit. AVIXA CABL-110 doesn't allow splices. Order the right reel up front.
Bundling everything together
Speaker, power and network on the left of the rack. Mic, line and video on the right, at least 100 mm (4 in) apart (CABL-106).
Need a starting point for the full system? Grab one of our free AV design templates, or browse the rest of our free AV calculators.
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Cable Length Calculator FAQs
Start with the horizontal distance from the plan and multiply it by a routing factor for sag and turns. Add the vertical rise at the source and drop at the destination, plus a service loop at each end. Multiply by one plus your waste allowance, usually 10%, to get the length to order.
AVIXA doesn't set a fixed slack length. It verifies that each device can be moved to a serviceable spot and re-terminated. Many integrators leave 1 to 3 m (3 to 10 ft) of service loop at the rack end and 0.5 to 1.5 m at the device, then add 10% waste. Add rack travel for pull-out or swing racks.
For reliable 4K60, plan on about 10 m (33 ft) for a passive HDMI 2.0 cable and 5 m (16 ft) for passive HDMI 2.1. Longer runs need an active optical HDMI cable or an HDBaseT extender, which can reach 100 m (328 ft) over Cat6A.
100 m (328 ft) total channel length, which includes patch cords at both ends. The same limit applies to Dante, AV-over-IP and HDBaseT. Some 4K HDBaseT extenders are only rated to 40 m, so check the extender's spec.
It depends on the run length and the load. For an 8Ω speaker, 16 AWG keeps loss under 11% up to about 18 m (60 ft), 14 AWG to 29 m (95 ft) and 12 AWG to 46 m (151 ft). 70V systems can use thinner wire over much longer distances because the current is lower.
A 70V line presents a much higher impedance to the wire than an 8Ω speaker, so far less current flows and much less power is lost in the cable. A 60 W, 70V zone on 16 AWG can run about 186 m (609 ft) before reaching 11% loss.
No. It calculates the run from source to destination. Add patch cords at the rack and the device separately, and remember they count toward the 100 m limit on Cat6.
Yes, for the parts decided at planning time. It applies the cabling items in the AVIXA Audiovisual Systems Performance Verification Guide for ANSI/InfoComm 10:2013: unique cable IDs for labeling (CABL-105), distance within spec (CABL-115), service loops (CABL-116), no splices and rack travel (CABL-110), bend radius in conduit (CABL-100), bundling by signal type (CABL-106 and 109) and expected loudspeaker line impedance (AP-124). On-site items like label durability and connector seating still need to be checked during verification.
Yes. Share creates a public link with the whole project stored inside it, so anyone you send it to sees the same cables and can edit their own copy. Nothing is saved on a server. PDF downloads a report with the project diagram, cable schedule, bill of cable and AVIXA verification checks.
Yes. The length math is the same for any cable pulled through a building. Pick Cat6 for network and security cameras, RS-232 for control, or fiber for backbone runs.
