TemplatesTemplate
Electrician invoice template
A polished invoice with the contractor's own brand and rates, ready to send.
THE EVERYDAY ELECTRICAL TOOLKITElectrical calculators for electricians. Right numbers.
Electrical calculators for electricians. Right numbers.
Better work.
From the first calculation to the final invoice.
Practical tools for electricians who get things done.
Free calculators No sign-up Made for the field
Voltage dropILLUSTRATIVE EXAMPLE
SUPPLY120 V
LOAD CURRENT20 A
Copper · 12 AWG100 ft · Single phase
CALCULATED VOLTAGE DROP6.58%
7.90 V · Resistance-only estimate
Know the method.Every calculator shows its formula.
36free calculators
NECUS code basis
3invoice styles
Private, browser-local calculations
THE TOOLBOX
Explore all 115 tools Less guesswork. More good work.
Calculators, practical references and documents. All in one place.
36 calculators · 6 templates · 55 quick tools · 18 references
TemplatesTemplate
Electrical estimate template
Turns a project scope into a professional estimate, quote or bid.
BasicsCalculator
Ohm’s law calculator
Free Ohm's law calculator: get current, power, voltage and resistance from voltage, resistance, current and power. The formula is shown; verify against the NEC.
ConductorsCalculator
Voltage drop calculator
Free voltage drop calculator: get voltage drop from voltage, current, one-way cable length, conductor area and resistivity at operating temperature.
SolarCalculator
Solar wire size calculator
Free solar wire size calculator: get minimum area (drop only) from voltage, current, one-way cable length and resistivity at operating temperature.
MotorsCalculator
HP to amps calculator
Free HP to amps calculator: get estimated current from mechanical output, voltage, power factor, efficiency and current. With the formula shown.
MotorsCalculator
Motor FLA calculator
Free motor FLA calculator: get estimated full-load current from output power, voltage and power factor. The formula is shown; verify against the NEC.
MotorsCalculator
Motor service factor calculator
Free motor service factor calculator: get service factor current from current, rated output, nameplate service factor and verified overload multiplier.
RacewayCalculator
Conduit fill calculator
Free conduit fill calculator: get fill and minimum internal diameter from conductor count, outside conductor diameter and internal conduit diameter.
RacewayCalculator
Conduit bending calculator
Free conduit bending calculator: get bend spacing and offset shrink from offset rise, rolling offset, bend angle, stub height and bender take-up.
RacewayCalculator
Box fill calculator
Free box fill calculator: get required volume from verified conductor equivalents, volume per equivalent, available box volume and non-ground conductor count.
PowerCalculator
Generator sizing calculator
Free generator sizing calculator: get peak load and design capacity from total simultaneous running load, largest additional starting surge and reserve margin.
PowerCalculator
Transformer sizing calculator
Free transformer sizing calculator: get load apparent power from secondary (load) voltage, current, primary voltage, growth allowance and design loading target.
ProtectionCalculator
Breaker size calculator
Free breaker size calculator: get minimum rating (125% continuous + noncontinuous) from continuous load current, noncontinuous load current and continuous load.
ProtectionCalculator
Fuse size calculator
Free fuse size calculator: get calculated maximum (flc × 175%) from motor flc from nec tables 430.247–430.250 (not nameplate). With the formula shown.
ConductorsCalculator
Ampacity calculator
Free ampacity calculator: get temperature correction factor (equation 310.15(b)). The formula and a worked example are shown; verify against the NEC.
ConductorsCalculator
Wire resistance calculator
Free wire resistance calculator for copper and aluminum by AWG or kcmil: resistance and conductance by length and temperature, with K values shown.
ProtectionCalculator
Available fault current calculator
Free available fault current calculator: transformer kVA, %Z and voltage, then the point-to-point method along the conductor, with working shown.
TEMPLATES
Invoice templates
The electrician invoice template, plus templates for the trades electricians work alongside.
LEARN BY CONNECTING
01 · WORKFLOW BUILDERSee the ideas behind the tools.
Find a topic or follow the checks that connect an electrical project.
Operation workflow diagrams
Flowcharts, mind maps and electrical project workflows, built and saved in the browser.
Build a workflow ↗02 · RELATIONSHIPSElectrical concept map
See how current, cable checks and protection relate.
Explore the concept map ↗A toolkit that travels.
US (NEC) calculations everywhere, with regional currency, tax labels and paper size for invoices and estimates.
The equation, explained.
Each page shows the calculation and its assumptions. Local standards remain part of the design checks.
Details stay on the device.
Calculations run in the browser. Invoice drafts stay on this device and saved projects remain in this browser. Export a JSON backup to move them to another device.
Estimating and invoicing tool
Ampxa is developing an estimating and invoicing application for electrical contractors. The list below receives notice when it opens.