MIG Wire Feed Speed & Deposition Rate Calculator

0.045 in steel wire in spray at 375 in/min. Weight per length = π/4 × 0.045² × 0.283 = 0.0004501 lb per inch (0.4501 lb per 1,000 in). Melt-off = 375 × 60 × 0.0004501 = 10.13 lb/h; at 98% electrode efficiency the deposition rate is 9.93 lb/h. Lincoln Electric’s procedure table lists 9.9 lb/h, and about 300 A, for that wire and feed speed.

How long a 33 lb spool lasts. 0.035 in wire at 250 in/min melts 250 × 60 × 0.0002723 = 4.084 lb/h, so the spool gives 33 ÷ 4.084 = 8.08 hours of arc time. With the arc on 40% of the time, that is 8.08 ÷ 0.40 = 20.2 hours, about two and a half 8-hour shifts.

The common mistake: treating the wire fed as weld metal. The 375 in/min example feeds 10.13 lb of wire an hour, but only 9.93 lb ends up in the weld; in short-circuit with CO₂ at 90% the gap is 10%. Costing from the wire fed overstates the weld metal you get. For the spool, use the melt-off rate, because the spool empties at the rate the wire is fed, not the rate it is deposited.

On a constant-voltage MIG machine you set the wire feed speed, and the current follows: the machine supplies whatever current melts the wire as fast as it arrives. Lincoln Electric’s Gas Metal Arc Welding Guide (C4.200) shows that relationship for each wire size, and notes that it does not go on for ever: 0.035 in wire is roughly linear up to about 200 A and saturates at about 280 A, near 720 in/min, after which more feed speed adds deposition but no more current. The guide gives wire drives as covering roughly 70 to 800 in/min, with high-speed feeders reaching 1,200 in/min (30 m/min).

The same guide separates melt-off rate, the wire melted, from deposition rate, what stays in the joint, and puts the difference down to spatter, smoke and slag formers: 93% or more for short-circuit with argon blends, down to 85% for globular transfer under CO₂, and about 98% for spray and pulse. Its shorthand 13.1 × D² × WFS × EE gives lb/h for solid steel wire; working it out from the 0.283 lb/in³ density it quotes gives 13.34, which matches the deposition rates in its own procedure tables (8.0 lb/h for 0.035 in wire at 500 in/min, 10.7 lb/h for 1/16 in wire at 210 in/min).

OSHA’s fact sheet on welding fume ranks flux-cored welding as the highest fume producer, then stick, MIG and TIG, and asks for local exhaust close to the arc; higher deposition rates mean more fume, so plan the ventilation with the rate.

This calculator works out the weight of solid wire per length from its diameter and density, and from that the melt-off and deposition rates for any wire feed speed, the feed speed for a deposition rate, and how long a spool lasts in arc hours and in shop hours. The efficiencies are Lincoln Electric’s for each transfer mode (the lower end where it gives a range) and Blodgett and Funderburk’s 80% for flux-cored wire. For carbon-steel wire in short-circuit or spray, it reads the approximate current from Lincoln’s procedure tables, interpolating only between the feed speeds they list.

Flux-cored and metal-cored wires are not solid metal, so use the weight per length from the wire’s data sheet. Currents and speeds are starting points: follow the wire maker’s data sheet and your welding procedure. Everything runs in your browser; nothing you enter is sent anywhere.

Related tools: Weld Metal & Filler Consumption Calculator, Shielding Gas Cylinder Duration Calculator, and Welding Amperage Chart.