What is the rule of thumb for calculating amperage required for welding?

• A. 1 amp for every 0.01 inch of metal thickness
• B. 1 amp for every 0.001 inch of metal thickness.
• C. 10 amps per 0.001 inch
• D. 0.5 amp per 0.001 inch

Answer: (B)

Heat control in welding scales with how thick the metal is. A simple starting rule is to set about 1 amp for every thousandth of an inch of thickness. So, a 0.125" plate would start around 125 A, while a 0.0625" sheet would start near 62–63 A. This proportional guideline helps you选择 a practical starting point because thicker metal needs more heat to fuse properly, and thinner metal risks burn-through if you push too much current. After starting, you adjust for the process (MIG, TIG, SMAW), wire or electrode size, joint type, and metal type, and always consult the manufacturer’s current ranges and perform test welds to dial in the settings.