To cut sheet metal, match the tool to the thickness and the shape of the cut: hand snips for thin sheet and curves, a nibbler or power shear for long cuts without distortion, and an abrasive or metal-cutting blade, or a plasma cutter, for thicker sheet. Mark the line, clamp the sheet, wear gloves and eye protection, and deburr the edge when you finish.
The rest of this guide covers how to read the thickness you have, which tool suits which job, step-by-step technique for straight lines, curves and holes, and how to stop a cut edge on galvanized or coated sheet from rusting.
Start With the Thickness
Sheet steel is usually sold by gauge, and a higher gauge number means thinner metal. Under the Manufacturers’ Standard Gauge for uncoated steel sheet, 26 gauge is 0.0179 in (0.45 mm), 22 gauge is 0.0299 in (0.76 mm), 18 gauge is 0.0478 in (1.21 mm) and 16 gauge is 0.0598 in (1.52 mm). Galvanized sheet runs slightly thicker at the same gauge number because of the zinc. Our steel gauge thickness chart lists every gauge from 7 to 28.
Measure with calipers if you are not sure, because the gauge decides the tool. Every snip, nibbler and shear has a rated capacity, usually printed on the tool or in its manual, and it is lower for stainless steel than for mild steel. Pushing a tool past its rating dulls the blades and leaves a ragged, bent edge.
Sheet Metal Cutting Tools Compared
| Tool | Best for | Cut quality | Watch out for |
|---|---|---|---|
| Aviation snips | Thin sheet, short cuts, curves, notches | Clean if blades are sharp; edge bends slightly | Hand fatigue on long cuts; check the rated gauge |
| Electric or pneumatic shear | Long straight or gently curved cuts in thin to medium sheet | Very clean, flat edges | Struggles with tight curves |
| Nibbler | Corrugated roofing, tight curves, cutouts | Flat sheet, slightly scalloped edge | Throws small sharp crescents of metal |
| Jigsaw with metal blade | Curves and cutouts, holes started from a drilled pilot | Fair; vibration can chatter thin sheet | Back the sheet with scrap plywood to stop chatter |
| Circular saw with metal-cutting blade | Long straight cuts in thicker sheet | Good with the right blade | Hot chips; use only blades rated for metal |
| Angle grinder with cutoff wheel | Quick rough cuts, trimming, thicker sheet | Rough, burred edge | Sparks, heat, burns off coatings near the cut |
| Plasma cutter | Thicker sheet and plate, shapes, any conductive metal | Fast; some dross and a heat-affected zone | Fumes, arc light, needs air and power |
For thick work, Hypertherm, a plasma equipment maker, describes plasma as “best for cutting metal between 6 and 80 mm,” notes that it only cuts electrically conductive metals, and says laser is typically used on material 6 mm and below, in its guide to choosing a cutting process (checked November 2026). Most handheld plasma units also cut thinner sheet, but on very thin gauges the heat can warp the panel.
How to Cut Sheet Metal With Snips
Aviation snips (also called compound snips) come in three common patterns, often color-coded on the handles: yellow cuts straight, red cuts curves to the left and green cuts curves to the right. The handle color is a widely used convention, but always check the marking on your pair.
Step by step
- Mark the line with a fine marker or scribe. Use a straightedge for straight lines and a template for curves.
- Clamp or support the sheet so it cannot flex or drop. Let the waste side hang free so it can curl away.
- Open the snips fully and cut with long strokes, but do not close the jaws all the way at the end of each stroke. Closing fully leaves a small notch at every stroke.
- Keep the snip blades upright to the sheet. Tilting them crushes the edge.
- For an inside cutout, drill a starter hole in the waste area, then cut out toward the line.
- Deburr the edge with a file or deburring tool, moving along the edge, not across it.
How to Cut Long Straight Lines
Snips work for short cuts, but on a long panel they leave a wavy edge and wear out your hand. For long straight cuts you have three good options.
Power shear or nibbler
An electric shear cuts like a powered pair of snips and leaves a flat, clean edge. A nibbler punches out a narrow strip, so the sheet on both sides stays flat, which is why roofers use nibblers on corrugated and ribbed panels. Run either tool against a clamped straightedge for a true line.
Circular saw with a metal blade
Use only a blade marked for ferrous metal or for the sheet you are cutting, and never a wood blade. Support the sheet on both sides of the line on sacrificial boards so the kerf does not pinch. Expect hot chips, so wear a face shield, long sleeves and hearing protection.
Score and snap
For very thin sheet such as flashing, scoring the line several times with a utility knife or scribe and bending the sheet back and forth along it will break it cleanly. It does not work on heavier gauges.
Cutting Thicker Sheet and Plate
As sheet gets heavier, hand tools stop being practical. An angle grinder with a thin cutoff wheel is the common workshop answer: score along the line with a light first pass, then cut through. Let the wheel do the work and keep the guard on.
Fabrication shops use sawing, oxy-fuel and plasma for heavier material. The Steel Construction Institute’s steelconstruction.info guide to fabrication (checked November 2026) explains that oxy-fuel cutting preheats steel to roughly 700 to 900°C and then uses a jet of pure oxygen, and that plasma constricts an arc through a copper nozzle into a jet in excess of 20,000°C. Oxy-fuel works on carbon steel, not stainless or aluminum, so for those metals plasma or a saw is the usual choice. For textured sheet like diamond plate, cut from the smooth side when you can so the blade or wheel does not catch on the raised pattern.
Cutting Galvanized, Coated and Stainless Sheet
Most building sheet is coated. Galvanized steel carries zinc, Galvalume carries an aluminum-zinc alloy, and roofing panels often have a factory paint layer on top. How you cut affects how long the coating lasts.
- Prefer cold cuts. Snips, shears and nibblers do not heat the sheet. Grinders and abrasive saws burn the coating back from the edge and throw hot particles that can embed in nearby painted panels and rust as orange specks.
- Ventilate when you use heat. Grinding, plasma or torch cutting galvanized steel releases zinc fumes. The precautions are the same as in our guide to welding galvanized steel.
- Seal raw edges. A cut exposes bare steel at the edge. Thin zinc coatings protect a narrow cut edge to some extent, but touch up visible edges on painted panels with the manufacturer’s touch-up paint. See our rust prevention coating guide for primer options.
- Stainless steel work-hardens. Use sharp blades, steady pressure and tools rated for stainless, and keep tools that have cut carbon steel away from it so iron particles do not cause rust spots.
Safety Basics
Fresh sheet metal edges cut like a knife. Wear cut-resistant gloves while handling and cutting, and safety glasses at all times. Add a face shield and hearing protection for saws, grinders and nibblers. Clamp work rather than holding it, keep a fire extinguisher nearby when you make sparks, and sweep up chips and nibbler crescents before they end up in shoes or tires.
If you are cutting openings in metal framing, such as through metal studs or into a metal building’s wall panels or girts, check first whether the member carries load. Cutting into a structural member, deck or panel that is part of a building’s bracing should be reviewed by a licensed structural engineer.
FAQ
What is the easiest way to cut sheet metal?
For thin sheet and short cuts, aviation snips are the easiest and cheapest. For long cuts, an electric shear or nibbler is faster and leaves a flatter edge.
Can you cut sheet metal with a jigsaw?
Yes, with a blade made for metal and a slow to medium speed. Clamp the sheet to scrap plywood so it does not vibrate, and drill a pilot hole to start inside cutouts.
How do you cut sheet metal without bending it?
Use a nibbler or power shear, support the sheet on both sides of the line, and let the waste side curl away. Snips bend the edge slightly because the blades push the metal apart as they cut.
Can I cut metal roofing with a grinder?
You can, but many panel makers advise against abrasive cutting because the heat damages the coating and the hot particles stain nearby panels. Snips, shears or a nibbler are the usual recommendation; check the panel manufacturer’s installation guide.
What gauge can tin snips cut?
It depends on the snip. The maximum gauge for mild steel, and a lower one for stainless, is usually printed on the tool or its packaging. Stay within that rating.
Reference information only, not engineering advice. Disclaimer.