The short answer
Choose 800W when most work is thin sheet, portability matters and you want to reduce upfront cost. Choose 1200W when thicker material and throughput matter enough to justify more power and, often, a higher system price.
How thickness changes the decision
Manufacturer-published examples show the gap clearly. xTool lists its MetalFab 800W up to 4 mm on stainless/carbon steel and 3 mm on aluminum, versus 5 mm and 4 mm respectively for the 1200W version. GWEIKE similarly publishes 0.2–4 mm versus 0.2–5 mm processing ranges.
Portability and workflow
Power is only one dimension. An 800W integrated system may fit mobile repair or a crowded small shop better, while 1200W can make more sense when the machine stays in place and earns its keep through higher throughput.
Decision checklist
- List the thickest material you routinely weld—not the rare maximum.
- Separate welding thickness from cutting claims.
- Confirm electrical requirements.
- Price the complete package, consumables and safety controls.
Safety note: Handheld fiber laser welders are high-power Class 4 laser systems. Use appropriate engineering controls, laser-rated PPE, training and a controlled work area. Always follow the exact manufacturer manual.