How to measure cable runs on an electrical plan
Quick answer
Trace each cable or containment run as a linear measurement on the plan, then add vertical drops and risers (which don't show as length on a plan) plus a slack allowance. Keep circuits or cable types in separate conditions. Solid Takeoff totals the runs; you add drops and slack.
Plans show cable routes as horizontal lines, but real cable also goes up and down — to sockets, switches, panels and across ceiling voids — and none of that vertical distance appears as length on a flat drawing.
So cable takeoff is: measure the horizontal runs accurately, then add realistic allowances for drops, risers and slack, kept tidy by circuit or cable type.
Step by step
- 1
Set the scale
Calibrate the plan with a preset ratio or by drawing a known dimension.
- 2
Create a condition per cable/containment type
Different sizes and types price differently — e.g. "2.5mm² T&E", "100 mm tray" — so give each its own linear condition.
- 3
Trace the horizontal runs
With the linear tool, follow each route along the plan, clicking at bends and finishing the run. The length totals live.
- 4
Add drops and risers
For each accessory add its drop (e.g. ~0.5 m to a socket from the ceiling void, more to a high-level switch) and add riser lengths between floors. These aren't on the plan — add them from the mounting heights.
- 5
Allow slack and terminations
Add a slack/waste allowance (commonly ~10%) for routing, terminations and pulling, so the ordered length is realistic.
- 6
Export
Export a CSV of run lengths by type for your estimate, plus an annotated PDF showing the routes.
Tips & gotchas
- •Plans show horizontal only — always add drops, risers and slack.
- •One condition per cable size/type; don't mix 1.5 and 2.5 mm².
- •Drops come from mounting heights (socket ≈ 0.45 m, switch ≈ 1.2 m) — add per point.
- •Add ~10% slack for routing and terminations.
- •Measure containment (tray/trunking) separately from the cable it carries.
Frequently asked questions
How do I measure cable length from a plan?
Trace the horizontal route as a linear measurement, then add vertical drops and risers (from the mounting heights, since they don't appear on a plan) and a slack allowance. Keep each cable type in its own condition.
Why is my cable quantity too low?
Almost always because only the horizontal plan length was measured. Add drops to each accessory, risers between floors, and ~10% slack for routing and terminations.
Should I measure containment separately?
Yes — measure tray, trunking and conduit as their own linear conditions (by size), separate from the cable inside them.
Is it free?
Yes — linear measurement and export are on Solid Takeoff's free plan.
Try it on your own plan — free
Open a PDF and measure in your browser. No card, no install, no CAD. Free plan forever.