Electrical Boxes Count Calculator

Plan devices by location with clear gang strategies and packing options built‑in. Enter outlets, switches, low‑voltage, fans, and junctions per space including spare allowance. Auto‑pack calculates 4‑, 3‑, 2‑gang mixes, minimizing wall clutter and box count. Instantly see totals per room and project‑wide summary with breakdowns. Export tables to CSV or PDF for submittals.

Tip: Use Auto‑Pack to distribute devices into 4/3/2‑gang boxes. The calculator then computes singles automatically, adds dedicated junction and fan boxes, and totals everything project‑wide.
Input Table
Enter device counts per location. Optionally choose a maximum gang size, then click Auto‑Pack.
Location Outlets Switches Dimmers Low‑Voltage Junction Fan Spare % Max Gang 4‑Gang 3‑Gang 2‑Gang Singles
(auto)		 Total Boxes
(auto)		 Actions
Singles derive from devices after multi‑gang and spares.
Results
Location Devices Devices + Spare Singles 2‑Gang 3‑Gang 4‑Gang Junction Fan Total Boxes
Total 0 0 0 0 0 0 0 0 0
Formula used

For each row, devices are summed and adjusted by spare percentage. Multi‑gang selections reduce singles. Dedicated junction and fan boxes are then added.

devices = outlets + switches + dimmers + lowVoltage
devicesWithSpare = ceil(devices × (1 + spare%/100))
multiCapacity = 2×twoGang + 3×threeGang + 4×fourGang
singles = max(0, devicesWithSpare − multiCapacity)
totalBoxes = singles + twoGang + threeGang + fourGang + junction + fan

Auto‑Pack uses a greedy approach: pack up to Max Gang (4→3→2) then assign remaining as singles.

How to use
  1. Pick a preset or add rows for each location.
  2. Enter device counts and optional spare percentage.
  3. Choose a Max Gang size and click Auto‑Pack for each row, or use Auto‑Pack All.
  4. Manually tweak 2‑, 3‑, and 4‑gang counts if desired.
  5. Click Recalculate to update singles and totals.
  6. Export results as CSV or PDF for sharing.

Always verify against local electrical codes and project specifications. This tool is a planning aid, not a substitute for professional judgment.

Example data table
These sample rows mirror the presets for quick testing.
LocationOutletsSwitchesDimmersLow‑VoltageJunctionFanSpare %Max Gang
Living Room83121154
Kitchen1240420103
Bedroom 162011102

For planning the number of boxes, many teams count data/low‑voltage points as devices. However, check whether separate bracket styles or gangable low‑voltage rings change the count or gang combinations.

Yes. Dedicated junction boxes are added on top of device boxes. Enter them per location or per branch run and they are included directly in the total.

Select the largest gang size you’ll allow at that location. Auto‑Pack fills 4‑gang first (if allowed), then 3‑gang, then 2‑gang, leaving the remainder as singles.

Absolutely. After Auto‑Pack, adjust the 2‑, 3‑, and 4‑gang fields manually. Click Recalculate to update singles and totals instantly.

No. This tool counts boxes and gangs for planning. Box‑fill calculations require conductor counts, volume allowances, device yokes, and specific box models. Verify with applicable codes and manufacturer data.

Common planning spares range from 5–15% depending on project uncertainty and client change risk. You can set this per location to reflect different design stages.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.