Choosing the right power is one of the most important decisions when buying a fibre laser cutting machine and one of the easiest to get wrong. Under-specify, and you’ll be limited on the thicknesses and speeds you can offer. Over-specify, and you’ll tie up capital and pay higher running costs for capability you never use.
So how much power do you actually need? This guide explains what each wattage band can do, from 3kW right up to 60kW, and how to match a machine to the work your business really does.
How to think about fibre laser power
Laser power influences two things: the maximum thickness you can cut, and the speed at which you cut it. But there’s an important subtlety that catches many buyers out the relationship isn’t linear. Doubling the power doesn’t double the thickness you can cut; it typically adds only around half as much again, and the returns shrink further as you climb the scale. In practice, this means high-power machines are less about cutting dramatically thicker plate and more about cutting mid-range material much faster.
Material matters too. Mild steel is the easiest to cut at greater thicknesses, while aluminium, copper and brass reflect more of the beam and draw heat away quickly, so they need more power to achieve similar results. Keep both points in mind as you read the bands below.
Fibre laser cutting capacity by power
The table below shows approximate maximum production thicknesses with good edge quality. Actual figures depend on the material, assist gas, machine and conditions, so treat them as a guide rather than absolute limits.
| Power | Mild steel | Stainless | Aluminium | Best for |
| 3kW | ~12–20mm | ~8–12mm | ~6–10mm | Thin sheet, light fabrication |
| 6kW | ~20–25mm | ~12–15mm | ~10–12mm | Most SMEs versatile all-rounder |
| 8–12kW | ~30mm | ~25–30mm | ~20–25mm | Thicker plate, higher throughput |
| 15–20kW | ~40–50mm | ~30mm | ~30mm | Heavy plate, high-volume production |
| 30–60kW | ~60–100mm+ | ~50–90mm | ~40–60mm | Ultra-thick plate, heavy industry |
Breaking down the power bands
3kW: The thin-sheet workhorse. Ideal for smaller fabrication shops, light engineering and businesses whose workload is mostly 1–8mm sheet. A 3kW machine cuts thin material cleanly and affordably, with the lowest entry cost and running costs, but it slows noticeably on thicker plate.
6kW: The versatile sweet spot. For most small and medium fabricators, 6kW is the ideal balance of thickness capability, speed and cost. It comfortably handles the vast majority of everyday job-shop work, cutting thin material quickly and mid-range plate capably. If you’re unsure, this is where most businesses land.
8 to 12kW: Medium-to-heavy plate and throughput. These machines come into their own for thicker materials and higher volumes. The real benefit isn’t just the extra thickness it’s the dramatic increase in cutting speed on 6–20mm material, which suits multi-shift operations and shops doing structural steel or thick stainless.
15–20kW: Heavy plate and high volume. Built for fabricators cutting thick plate daily or running continuous, high-output production. At this level, a single machine can replace multiple plasma tables and deliver extreme speed on mid-thickness material.
30kW to 60kW: Ultra-high power. The top of the range is specialist territory heavy industry, shipbuilding and structural work involving very thick plate. These machines deliver maximum throughput on thick material, but they’re a significant investment with high running costs, and only make sense where the workload genuinely demands them.
Other factors that affect the power you need
Power is the headline figure, but a few other things shape the decision:
- Material type. If you regularly cut reflective metals like aluminium, copper or brass, you’ll need more power than the equivalent work in mild steel.
- Assist gas. Nitrogen gives a clean, oxide-free edge (ideal for stainless and aluminium), oxygen helps cut thicker mild steel, and air cutting offers much lower running costs for general work.
- Speed and volume. If throughput is critical, higher power pays off by cutting cycle times even on materials a lower-powered machine could technically handle.
- Edge quality. The finish you need on your parts influences the power-and-speed balance that works best.
How to choose the right power for your business
The simplest approach is to match the machine to two things: the thickest material you regularly cut, and the volume you need to produce. Base the decision on your typical, everyday work rather than the occasional one-off thick job it’s usually cheaper to outsource the rare exception than to buy power you’ll seldom use.
Avoid the two common mistakes: under-specifying and limiting what you can take on, or over-specifying and paying a premium in capital and running costs for capability that sits idle. For many businesses, 6kW hits the mark, but the right answer depends entirely on your materials and volumes. Naturally, higher power means a higher price too our separate fibre laser cost guide explains how pricing scales with wattage.
Get expert advice on the right power
The best way to choose is to talk it through with a specialist who understands your materials, thicknesses and production goals. At Axe & Status, we help UK fabricators select the right fibre laser for their business, matching power and specification to the work you actually do, and backing it with professional installation, training and support. Get in touch to discuss your requirements.
FAQs
What power fibre laser do I need?
It depends on the thickest material you regularly cut and your production volume. Most small and medium fabricators find 6kW offers the best all-round balance, while thin-sheet work suits 3kW and heavy plate or high-volume production calls for 12kW and above.
What can a 6kW fibre laser cut?
A 6kW fibre laser typically cuts mild steel up to around 20–25mm, stainless steel up to around 12–15mm, and aluminium up to around 10–12mm with good quality, while cutting thinner material very quickly. Exact figures depend on the assist gas, machine and conditions.
Is more power always better?
No. Higher power increases speed and thickness capability, but the gains in thickness are smaller than many expect, and running and capital costs rise sharply. The best choice matches your typical materials and volumes rather than simply buying the most powerful machine available.
