Electrician Calculator
Calculate the total wire length and costs for your electrical project. Get accurate calculations based on wire cross-section, material, and number of circuits.
Accurate Wire Length and Cost Calculation
Our electrician calculator helps you determine the total wire length needed and costs for your electrical project. Simply enter the wire length per circuit, select the wire cross-section and material, and specify the number of circuits. The calculator will provide you with detailed cost estimates including wire costs and labor fees based on the selected wire type.
Results
WIRE
Cost Breakdown
How to Estimate Wire for a Circuit
Wire is estimated by run length, not by straight-line distance, and the two are rarely close. Measure the actual path — up the wall, across the joists, back down — then add 15 to 20% for routing and 12 to 18 inches of tail at every box. Buy by the standard coil, because cutting a 250 foot roll for a 190 foot job leaves you with 60 usable feet, not scrap.
1. Trace the real path
From the panel, up to the top plate, along the run, down to each device. A 30 foot straight-line distance is often a 55 foot pull once it goes up and over.
2. Add tails at every box
12 to 18 inches of free conductor at each device box and considerably more at the panel. On a circuit with ten devices those tails alone are 15 feet.
3. Add a routing allowance
15% on an open frame, 20% or more on a remodel where you are fishing around obstacles you cannot see.
4. Check the gauge against the breaker
14 AWG on a 15 amp circuit, 12 AWG on 20 amp, 10 AWG on 30. Get this wrong and the material estimate is the least of the problem.
5. Round to a standard coil
Romex comes in 25, 50, 100, 250 and 1,000 foot rolls. A 190 foot requirement buys a 250 foot roll — the remainder is stock, not waste.
Worked Example: a 20 Amp Kitchen Circuit
12/2 Romex, panel to six receptacles, open frame, single storey.
| Item | Working | Result |
|---|---|---|
| Panel to first box, traced path | up 8, across 22, down 4 | 34 ft |
| Box to box, 5 hops | 5 x 9 ft average | 45 ft |
| Tails | 6 boxes x 1.25 ft, plus 6 ft at the panel | 13.5 ft |
| Subtotal | 34 + 45 + 13.5 | 92.5 ft |
| 15% routing allowance | 92.5 x 1.15 | ~107 ft |
| Buy | next standard coil up | 250 ft roll |
Gauge, Breaker and Common Use
| Gauge | Breaker | Typical use |
|---|---|---|
| 14 AWG | 15 A | Lighting circuits, general receptacles. |
| 12 AWG | 20 A | Kitchen and bathroom small appliance circuits. |
| 10 AWG | 30 A | Dryers, water heaters, subpanel feeds. |
| 8 AWG | 40–50 A | Ranges, larger feeds. |
| 6 AWG | 55–65 A | Subpanels, EV chargers at higher amperage. |
What a Wiring Job Costs
Cable is cheap and getting it into the wall is not. The calculator above sizes the run and gives you the length. The price of the job is set by whether the walls are open, how many openings there are, and what the panel can take. A circuit run through stripped-back framing and the same circuit fished through a finished, occupied house are the same materials and nothing like the same invoice.
Open walls or finished walls
This is the single biggest multiplier in residential electrical work. In open framing a run is drilled and stapled in minutes. In a finished house it has to be fished, which means rods, access holes, and then someone to patch and paint them. Establish which one you are looking at before quoting anything.
The run is longer than the straight line
Cable follows the framing, up and over, around obstructions, with slack left in every box. Measure the route rather than the distance between the two ends, and add for the drops and the loops at each device.
Openings, not feet
Most of the labour is at the ends: boxes, devices, plates, terminations, testing. A long run with two devices is quicker than a short run with nine. Count the openings and price those, then add the cable.
Conductor size
Going up a gauge for voltage drop on a long run is a copper cost that scales with the whole length, and it can mean larger boxes and a stiffer cable that takes longer to pull. The calculator sizes it for the load and the distance, so the decision comes off numbers rather than habit.
What the panel can take
If the panel is full or the service is undersized, the circuit you were asked for turns into a subpanel or a service upgrade with a utility appointment attached. Check the panel first. This is the item that turns a modest quote into a large one.
Permit and inspection
Permit fees, the inspection appointment and any rework are part of the job on anything notifiable. The time spent waiting on an inspector belongs in the quote rather than in your evening.
The Lines Behind an Electrical Price
| Line item | What drives it |
|---|---|
| Cable | Route length including drops and slack, at the gauge the load and distance require |
| Boxes and devices | Number of openings, device type, plates |
| Breaker and panel work | Spare ways in the panel, breaker type, whether a subpanel is needed |
| Rough-in labour | Open framing or fishing through finished walls, plus drilling and fire-stopping |
| Access damage | Cutting, patching and painting where a cable had to get through |
| Trim-out and testing | Terminations, devices, labelling, testing every circuit |
| Permit and inspection | Fees, the appointment, and any correction visit |
| Access and conditions | Crawl spaces, attics in summer, occupied rooms, working around other trades |
Where Estimates Go Wrong
Estimating from the floor plan distance
Wire does not travel diagonally through framing. The traced path is routinely half again as long as the plan suggests.
Forgetting the tails
A foot at every box sounds trivial until the circuit has fifteen of them and you are eighteen feet short at the far end.
Treating a remodel like new construction
Fishing wire through a finished wall means going around things you cannot see. The allowance has to be bigger, not the same.
Electrician Calculator — Common Questions
What does it cost to run a new circuit?
Cable is a small part of it. The number turns on whether the walls are open or the cable has to be fished through a finished house, how many boxes and devices are at the ends of the run, and whether the panel has a spare way. A full panel turns a modest quote into a subpanel or a service upgrade, so check that before you price anything else.
How much wire do I need for a circuit?
Measure the traced path rather than the straight line, add 12 to 18 inches at each box, then add 15% on open framing or 20% on a remodel.
What size wire for a 20 amp circuit?
12 AWG. 14 AWG is for 15 amp circuits and 10 AWG for 30 amp.
How much extra wire should I allow?
15% on new work with open framing, 20% or more when fishing through finished walls where the route cannot be seen in advance.
What lengths does Romex come in?
Commonly 25, 50, 100, 250 and 1,000 foot rolls. Round up to the next coil — the remainder goes on the van as stock.
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