mm
mm
Inside height available for cables.
m
Used to estimate total weight.
Choose typical project presets.
0.70–0.90 typical.
0%
kg/m
Compare against weight per length of installed cables.
×
Applies to load when checking rating (e.g., 1.5).
Pick a saved span-rating pair for this project.
Set target fill per your governing standard. Presets are generic guidance, not a substitute for code or manufacturer data.
Cables in tray
Weight/length in kg/m or lb/ft
| Cable type | Outside Ø | Count | Weight/length | Area/each | Total area | Total weight | |
|---|---|---|---|---|---|---|---|
| Sum of cable areas | — | — | — | ||||
Tray, Fill & Load Checks
Tray usable area
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Occupied (packed) area
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Achieved fill
—
Effective target
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Remaining to target
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Total weight
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Weight per length
—
Rating utilization
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Addable limits
| Cable type | Max extra before target |
Max extra before rating |
Combined max extra (min) |
|---|
Combined limit is the minimum of target- and rating-based allowances.
Project & support-span presets
| Support span | Rating per length |
|---|
Spans are stored per project in your browser. Values auto-convert between metric and imperial display.
Custom presets
Saves units, tray size, target, packing, margin, run length, and tray rating to your browser.
Example data
| Name | Outside Ø | Count | Weight/length | Notes |
|---|---|---|---|---|
| CAT6 UTP | 6.5 mm | 60 | 0.04 kg/m | Typical data cable |
| 12C Fiber | 3.0 mm | 24 | 0.01 kg/m | Distribution fiber |
| MC 12/2 | 12.0 mm | 10 | 0.18 kg/m | Power cable |
Use "Load example" to populate these rows into the calculator.
Formulas used
- A_tray = W × D where W is usable width and D is usable depth.
- Cable cross‑section (assumed circular): A_i = π/4 × d_i², total for type i is A_i × count_i.
- Packing inefficiency factor PF (0.70–0.90 typical): A_packed = ΣA / PF.
- Effective target with safety margin M: %Target_eff = max(0, Target − M).
- Achieved fill: %Fill = 100 × A_packed / A_tray.
- Remaining capacity to target: A_rem = max(0, Target_eff% × A_tray − A_packed).
- Weight per type: W_total,j = w_l × count_j × L, where w_l is weight/length and L is run length.
- Rating utilization with safety factor SF: %Util = 100 × (SF × W/L) / R.
- Max extra by rating for type j: N_max,rate = floor( max(0, R − SF × W/L) / w_l ).
Always verify with the project’s governing code or standard. Adjust target fill and rating per manufacturer data.
How to use this calculator
- Choose units. Enter tray usable width and usable depth.
- Set run length for weight estimation, tray rating, and safety factor.
- Pick a preset or set your own target and packing factor.
- Use Project span presets or edit spans in the table below.
- Adjust the safety margin to reduce allowable fill.
- Add cable rows with outside diameter, count, and weight per length.
- Review fill %, rating utilization, and combined addable limits.
- Save custom presets and projects locally. Export CSV or PDF.
Tip: Values auto-convert between metric and imperial displays.
FAQs
The packing factor approximates how efficiently round cables occupy space in a rectangular tray. Values between 0.70 and 0.90 are common; higher values assume tighter, more uniform packing.
Follow your governing electrical code, company standards, or manufacturer instructions. This tool provides area-based estimates; code rules may specify different limits by cable type and tray construction.
Use a caliper across the widest point of the jacket. Prefer manufacturer datasheets when available; field measurements can vary with jacket tolerance and temperature.
Yes. The unit toggle converts tray dimensions, cable diameters, run length, weight/length, and span tables. Ensure inputs reflect consistent real-world measurements.
It multiplies the calculated weight per length before comparing to the tray rating. For example, a 1.5 factor models dynamic or seismic allowances conservatively.
Enter span length and rating pairs in the table, then save under a project name. Pick the project and apply a pair to set the tray rating quickly for consistent checks.
Yes. The rating-based allowance uses the factored load, so the combined minimum reflects both area targets and any additional safety factor you specify.