What Is a MIG Wire Feed Speed Calculator?
Wire feed speed (WFS) is the setting that controls how fast your MIG welder pushes wire into the arc. This calculator converts that setting into a deposition rate — pounds of weld metal per hour — using the wire's actual cross-sectional area, its feed speed, and the density of steel, a direct physical calculation rather than a rule-of-thumb estimate.
It also estimates wire consumption in feet per hour and how long a given spool will last at that feed speed, which is useful for planning consumables for a job.
How to Read Your Results
Deposited Weld Metal Rate
The rate at which weld metal actually ends up in the joint, after accounting for spatter losses (deposition efficiency). This is the number that matters most for productivity estimates.
Gross Melt-Off Rate
The total rate at which wire is being melted, before subtracting spatter loss — useful for estimating raw wire consumption.
Wire Consumption
How many feet of wire are fed per hour at your set wire feed speed — a simple unit conversion from inches per minute.
Estimated Spool Run Time
How long your entered spool weight will last, in hours and minutes, at this feed speed and melt-off rate.
Real-World Example
.035-inch solid steel wire, fed at 300 ipm, with 95% deposition efficiency, using a 33 lb spool:
| Quantity | Value |
|---|---|
| Wire cross-sectional area | π/4 × 0.035² ≈ 0.000962 in² |
| Gross melt-off rate | ≈4.92 lb/hr |
| Deposited rate (95%) | ≈4.67 lb/hr |
| Spool run time (33 lb) | ≈6.7 hours |
At 300 ipm, a standard 33 lb spool of .035" wire provides roughly 6-7 hours of arc-on welding time before it needs to be replaced.
Tips for Working With Wire Feed Speed
- Higher WFS means higher amperage on most constant-voltage MIG machines, but the exact relationship depends on your specific power source, wire type and shielding gas.
- Larger diameter wire deposits more metal per inch fed than smaller diameter wire at the same feed speed.
- Short-circuit transfer typically has lower deposition efficiency than spray transfer due to more spatter — adjust the efficiency input accordingly.
- Track actual spool life on the job and compare it to this estimate to refine your efficiency assumption over time.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team