# Welding Power Consumption and Cost Calculator

> Source: https://netray.co/tools/welding-power-consumption-cost-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Estimate input power, supply current and electricity cost of a welding power source from arc volts, amps, efficiency and tariff.

## Category

industry-templates

## Industry

Welding & Fabrication

## Audience

- Plant engineer
- Facility manager
- Fabrication shop owner

## Tool

**Kind:** calculator

**Inputs:**

#### Arc voltage

**Key:** volts

**Type:** number

**Default:** 28

**Min:** 0

**Step:** 0.5

**Unit:** V

#### Welding current

**Key:** amps

**Type:** number

**Default:** 300

**Min:** 0

**Step:** 10

**Unit:** A

#### Power source efficiency

**Key:** eff

**Type:** slider

**Default:** 85

**Min:** 50

**Max:** 95

**Step:** 1

**Unit:** %

**Help:** Inverters are often 80 to 90 percent; older transformer sets are lower.

#### Power factor

**Key:** pf

**Type:** slider

**Default:** 0.9

**Min:** 0.5

**Max:** 1

**Step:** 0.01

**Help:** Inverters with correction are near 0.9 to 0.95; uncorrected machines can be much lower.

#### Three-phase supply voltage

**Key:** mains

**Type:** select

**Default:** 415

**Options:**

##### 380 V

**Value:** 380

##### 400 V

**Value:** 400

##### 415 V

**Value:** 415

##### 460 V

**Value:** 460

##### 480 V

**Value:** 480

#### Arc-on hours per month

**Key:** hours

**Type:** number

**Default:** 120

**Min:** 0

**Step:** 5

**Unit:** h

#### Electricity tariff

**Key:** tariff

**Type:** number

**Default:** 0.12

**Min:** 0

**Step:** 0.01

**Unit:** per kWh

**Outputs:**

#### Arc output power

**Key:** arc_kw

**Expr:** volts * amps / 1000

**Format:** decimal

**Description:** kW delivered to the arc.

#### Input power

**Key:** in_kw

**Expr:** if(gt(eff,0), arc_kw * 100 / eff, 0)

**Format:** decimal

**Primary:** true

**Description:** kW drawn from the supply while welding.

#### Apparent power

**Key:** kva

**Expr:** if(gt(pf,0), in_kw / pf, 0)

**Format:** decimal

**Description:** kVA for cable, breaker and generator sizing.

#### Supply current (3-phase)

**Key:** line_a

**Expr:** if(gt(mains,0), kva * 1000 / (sqrt(3) * mains), 0)

**Format:** decimal

**Primary:** true

**Description:** Amps per phase.

#### Energy per month

**Key:** kwh

**Expr:** in_kw * hours

**Format:** decimal

**Description:** kWh while arc is on.

#### Electricity cost per month

**Key:** cost

**Expr:** kwh * tariff

**Format:** currency

**Description:** Excludes idle and standby draw.

**Chart:**

#### Input power (kW) vs welding current

**Type:** line

**X:** amps

**From:** 100

**To:** 500

**Steps:** 41

**Series:**

- in_kw

**Disclaimer:** Uses the entered arc voltage for every point on the chart. Real arc voltage rises with current, so treat the result as an estimate and verify with a power meter.

## Content

**Intro:** Sizing a supply, a generator or a power budget for welding starts with input kilowatts and kVA, not the number on the dial. This calculator converts arc volts and amps into input power, supply current and monthly electricity cost.

**Sections:**

#### How to use it

**Body:** Enter the typical arc voltage and welding current, the efficiency and power factor of the machine from its data sheet, and your supply voltage. Add arc-on hours per month and your tariff. The calculator returns arc power, input kW and kVA, per-phase supply current and the energy cost for welding. Use the supply current to check cable and breaker size, and kVA to size a generator with sensible margin.

#### The formulas

**Body:** Arc power in kW is volts times amps divided by 1000. Input power is arc power divided by efficiency. Apparent power in kVA is input power divided by power factor. Three-phase line current equals kVA times 1000 divided by the square root of three times line voltage. For example, 28 V at 300 A with 85 percent efficiency and 0.9 power factor draws about 9.9 kW, 11 kVA and roughly 15 A per phase at 415 V.

#### Interpreting the result

**Body:** The cost shown covers energy while the arc is on. Idle draw from fans, controls and wire feeders adds a smaller but constant load, which matters in shops with many machines left powered all day. Compare against gas and wire costs: electricity is usually the smallest of the three consumables, so efficiency gains pay back mostly through lower supply infrastructure and generator size, not the tariff.

**Bullets:**

- Use nameplate input current as a cross-check
- Add margin for generator starting surges
- Review power factor if utility penalties apply

#### Common mistakes

**Body:** Using welding current as if it were supply current is the classic error. The machine draws far less current from the mains than it delivers to the arc, because output voltage is low. Another is ignoring duty cycle: sizing for 100 percent when the real duty is 40 percent wastes capital, while ignoring peak demand can trip a breaker.

**Cta:** If energy per job matters for quoting, Netray can help bring metered consumption into your ERP costing, running on your own infrastructure.

**Faq:**

#### How many kW does a 300 A welder use?

**Answer:** At 28 V arc voltage, arc output is about 8.4 kW. With 85 percent efficiency the input is around 9.9 kW. Real draw varies with voltage, process and machine design, so measure if cost matters.

#### How do I size a generator for a welder?

**Answer:** Use input kVA at the highest current you will weld at, then add margin, commonly 25 to 50 percent, for starting surges and other loads. Check the machine manual for minimum generator guidance.

#### Why is supply current so much lower than welding current?

**Answer:** Arc voltage is low, about 20 to 35 V, while supply voltage is hundreds of volts. Power is roughly conserved, so current on the supply side is a small fraction of weld current.

#### Does power factor change my electricity bill?

**Answer:** Residential and many small industrial tariffs bill kWh only, but larger consumers may pay for kVA demand or low power factor penalties. It always affects cable and generator sizing.

## Search terms

welding machine power consumption calculator, welder kva calculation, welding electricity cost, inverter welder input current, kw consumption of welding machine, mig welder power requirement, welding machine generator size, three phase welder supply current

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