Technical reference

Laser Cutting Tolerances Chart: What You Can Actually Hold

Updated 2026-10-12 · 4 min read

Laser cutting is often described as a "high precision" process, but that label hides a wide range. The tolerance a machine can actually hold depends on material, thickness, the machine's own positioning accuracy, and how the part is supported. This page gives the ranges we see in practice, and how to specify tolerance so a supplier can meet it.

Quick answer: On thin sheet metal, a fiber laser typically holds ±0.05 to ±0.10 mm on profile dimensions. CO2 lasers and thicker material sit around ±0.10 to ±0.25 mm. Machine positioning accuracy (commonly ±0.01 to ±0.05 mm) is not the same thing as the tolerance of the finished part.

Typical laser cutting tolerances by thickness

The figures below are practical ranges for a well-maintained machine with correct focus, clean optics and a supported workpiece. Treat them as a starting point for a conversation with your supplier, not as a guarantee.

Material thickness	Fiber laser (typical)	CO2 laser (typical)	Kerf width
0.5 – 1 mm	±0.025 – 0.05 mm	±0.05 – 0.10 mm	0.10 – 0.20 mm
1 – 3 mm	±0.05 – 0.10 mm	±0.10 – 0.15 mm	0.15 – 0.30 mm
3 – 6 mm	±0.10 – 0.20 mm	±0.20 – 0.30 mm	0.25 – 0.45 mm
6 – 12 mm	±0.15 – 0.30 mm	±0.30 – 0.50 mm	0.40 – 0.70 mm
Over 12 mm	±0.25 – 0.50 mm	limited capacity	0.60 mm +

Two things are worth noting in that table. First, the jump between 3 mm and 6 mm is real — it is where thermal distortion starts to dominate over machine accuracy. Second, kerf width matters as much as tolerance: if you are cutting a 10 mm hole with a 0.4 mm kerf, the tool path has to be offset by half the kerf on each side, and any error in kerf compensation shows up directly in the finished size.

Tolerance versus positioning accuracy

These two numbers get confused constantly, and the confusion causes most arguments between buyers and suppliers.

Positioning accuracy is a property of the machine: how close the cutting head gets to the commanded coordinate, typically ±0.01 to ±0.05 mm. It is measured on the machine, often with a laser interferometer, without cutting anything.
Repeatability is how consistently it returns to the same point — usually similar to or better than positioning accuracy.
Part tolerance is what you measure on the finished part. It includes positioning error, kerf behaviour, thermal movement of the material, and any distortion released by cutting.

A machine with ±0.02 mm positioning accuracy will not produce ±0.02 mm parts in 6 mm steel. Expect the finished tolerance to be several times the positioning figure once real material is involved.

What actually drives the tolerance you get

Five factors account for most of the variation:

Material thickness and type. Stainless steel and aluminium conduct heat differently from carbon steel, so the heat-affected zone and distortion differ even at identical thickness.
Thermal distortion. Long, thin cuts release internal stress in the sheet as they go. This is why a 1000 mm long part is harder to hold than a 50 mm bracket from the same sheet.
Kerf taper. The cut is never perfectly parallel-sided. On thicker material the bottom of the kerf is narrower than the top, so a "hole" is slightly conical.
Workpiece support. A sheet that is not flat will not cut flat. Honeycomb, blade or vacuum tables all exist to solve this problem.
Machine condition. Contamination on the lens, a worn nozzle, or focus set to the wrong height will move you outside the tolerance band faster than anything else on this list.

ISO 9013: specifying cut quality, not just dimensions

Dimensional tolerance is only half the specification. ISO 9013 ("Thermal cutting — Classification of thermal cuts") is the standard that describes the quality of the cut itself, and it is the one to quote when the edge matters.

It classifies a thermal cut (flame, plasma or laser) into quality classes based on two measurable things:

Perpendicularity tolerance (u) — how far the cut face deviates from square through the thickness
Mean roughness (Rz5) — how rough the cut face is

Lower class numbers are better. Fine classes demand a slower cut and a well-maintained machine; coarser classes let you cut fast.

Class	Cut face quality	Typical use
1–2	Smooth, near-square face, minimal dross	Visible parts, welded edges, tight assemblies
3–4	Slightly rougher, small perpendicularity deviation	General fabrication, painted parts
5	Rough, visible drag lines	Non-critical, hidden or rough-cut parts

The practical value of quoting a class is that it tells the supplier how slow to run the machine, which is what actually determines your price. A part specified only by dimension will be cut at whatever speed the operator chooses; a part specified as ISO 9013 class 3 has a defined edge that can be inspected and rejected.

For laser cutting on thin sheet, classes 1–2 are realistic. As thickness rises, holding the tighter classes requires slowing down significantly, and class 3–4 becomes the economical choice. Ask your supplier which classes they can hold at your thickness before agreeing a price.

How to specify tolerance on a drawing

Most tolerance disputes come from drawings that specify nothing, leaving the supplier to guess.

State a general tolerance block on the drawing, for example "ISO 2768-m" or "ISO 2768-f". This covers every dimension that is not individually toleranced.
Tolerance only the features that matter — mating holes, bearing seats, slots that take a specific insert. Over-tolerancing everything raises cost without improving function.
Give a datum for dimensions that stack. Chained dimensions accumulate error; dimensions from a common datum do not.
Say which edges are cut edges and which are formed or machined, so the supplier knows where laser tolerance applies.
For holes, specify diameter and position separately. Position tolerance is usually looser than diameter tolerance on laser-cut parts.

When laser is the wrong process

If your part needs a tolerance tighter than roughly ±0.025 mm, or a surface finish better than a cut edge, laser cutting is not the finishing operation — it is the blanking operation. Common follow-on processes are:

CNC milling for tight bores, counterbores and flatness
Reaming or drilling for holes that take a press-fit pin
Grinding where flatness or thickness tolerance below the thermal distortion limit is required

Designing for laser means accepting a slightly tapered cut edge and putting the precision requirements only where they are needed.

Frequently asked questions

What is a normal laser cutting tolerance?

For thin sheet (up to 3 mm) a well-maintained fiber laser typically holds ±0.05 to ±0.10 mm on profile dimensions, tightening to about ±0.025 mm on very thin gauge with a good fixture. Thicker material and CO2 machines generally sit in the ±0.10 to ±0.25 mm band. Always confirm against the machine's positioning accuracy specification, not a generic figure.

Does laser cutting tolerance change with thickness?

Yes. Thermal distortion grows with thickness, and the kerf becomes more tapered as the beam penetrates deeper. A rule of thumb is that achievable tolerance roughly doubles between 1 mm and 6 mm material on the same machine.

What ISO standard covers general tolerances?

ISO 2768-1 defines general tolerances for linear and angular dimensions where no individual tolerance is stated — classes are designated fine (f), medium (m), coarse (c) and very coarse (v). Laser-cut parts are usually specified to class m or f, with critical features toleranced individually.

What is ISO 9013?

It is the standard for classifying thermal cuts (laser, plasma and flame) by cut quality — mainly perpendicularity tolerance and surface roughness. Classes run from 1 (finest) to 5. Quoting a class tells the supplier how slow to run the machine, which is what drives the price.

Is laser cutting more accurate than plasma cutting?

Substantially. Plasma cutting typically holds ±0.5 to ±1.0 mm on plate, while laser cutting on comparable thickness holds roughly ±0.1 to ±0.2 mm. Plasma is chosen for speed and thickness capacity, not precision.

Machines mentioned in this article

Fiber Laser Cutting Machine — Fiber sources hold the tightest tolerances on thin metal sheet
CO2 Laser Cutting Machine — CO2 machines suit non-metal and mixed material work
Metal Laser Cutting Machine — CO2 metal cutting in three bed sizes

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