CrewMeasure

Electrical Calculator

Estimate Tier 1 wire footage, boxes, and outlets with an editable slack allowance.

You'll need — ft of wire and — boxes for this job.

Tier 1 wire runs

Add a row for each branch-circuit run, then adjust the visible slack allowance for the job.

No wire runs entered yet. Wire footage stays blank until at least one run has a length.

Tier 1 boxes and outlets

Simple user-entered tally by type; these counts are not inferred from the run lengths.

Box fill (NEC 314.16(B) formula)

Optional. Enter a box volume and at least one conductor to check required box-fill volume against the box you're using. Skipped when left off.

Include box fill

Box fill checks whether an electrical box is legally large enough for the wires, devices, and clamps packed inside it. Turn this on if you already know your box's volume.

Wire sizing / voltage drop

Optional. Solves the minimum conductor size for a target voltage-drop budget using standard Ohm's-law-family physics and public AWG resistivity constants. Skipped when left off.

Include wire sizing

Voltage drop is power lost as heat over a long wire run, which can dim lights or undersize a circuit. Turn this on to size a conductor for a long run.

GFCI/AFCI location prompts

Optional. Tag devices by location to raise a check-this prompt on the common GFCI cases (kitchen countertop, bathroom, garage, outdoor, unfinished basement/crawlspace) and on bedroom AFCI. These are prompts, not the code's own lists, and a device left unflagged has only not been checked.

Include location flags

GFCI protects against shock near water; AFCI protects against arc-fault fires. Turn this on to raise a prompt on the common cases by location -- it will not tell you every place protection is required.

Circuit / breaker grouping

Optional. Suggests circuit groupings so each circuit's summed load stays at or under 80% of the breaker rating. Simple rule of thumb -- verify locally before finalizing panel scheduling.

Include circuit grouping

Turn this on to sort a list of device loads into circuits that each stay safely under 80% of the breaker rating.

You'll need — ft of wire and — boxes for this job.

You'll need

Combined wire and box estimate

Warnings

  • INFO Advanced code table lookup is not available until reference data is verified.
  • INFO This is a general reference only. Verify local requirements and field conditions before installation.

Detail values

Assumptions

  • Slack allowance: 10% -- estimated: the ordinary allowance for coiling at boxes and pulling slack, on top of the measured run. NOT a code figure and it cites no section; the free-conductor length required at each box is a per-box minimum from the code book and does not convert to a percentage of a run
  • Estimated cable securement: 1 strap every 4.5 ft of run, plus 1 at each box

Included: wire footage with slack allowance, cable staples/straps, junction boxes, device boxes, receptacles, switches.

Not included: labor, permits, inspection fees, fixtures and fittings beyond what's itemized above.

Formula details
  • Wire footage: sum(runLengths) * (1 + slackAllowancePercent / 100)
  • Cable staples/straps: ceil(baseWireFootage / cableSupportSpacing + junctionBoxes + deviceBoxes)

    Estimated -- a purchasing figure at the ordinary trade spacing, plus one strap at each box. It is NOT a securing schedule and cites no code section: the required support interval, how close a strap must sit to each box, and what counts as supported where cable passes through bored framing all come from the code book and the cable's own listing. Counted off the base run footage, because the slack allowance is coiled at the boxes rather than run along framing.

Tier 2 conduit fill

Advanced code table lookup is not available until reference data is verified.

Conduit fill inputs unavailable

Verified NEC Chapter 9 Table 4 and Table 5 data is required before fill limits or pass/fail results can be calculated.

Material List

About this calculator

Sum your actual run lengths, keep the slack assumption visible, and use the tally fields for simple box and outlet counts.

FAQ

Why is the slack allowance editable?

CrewMeasure starts at 10%, but job conditions such as box drops, splices, and service loops can require a different allowance.

Why is conduit fill unavailable?

Conduit fill needs verified NEC Chapter 9 Table 4 and Table 5 datasets. CrewMeasure does not substitute unverified values.

Disclaimer

This is a general reference and material-estimate tool only. Verify local requirements, equipment specifications, and field conditions before installation.