Buy a plasma cutter based on what you’ll actually cut, not the maximum thickness listed on the box. A 45A machine with pilot arc start and a built-in air filter handles 90% of small shop cutting on steel up to 5/8" thick. That’s the sweet spot for hobbyists and small fabrication shops. If you regularly cut 3/4" and thicker, step up to 65A or more. Everything else, including brand, features, and input power, follows from that amperage decision.
The plasma cutter market ranges from $300 budget units to $5,000+ industrial machines. The differences aren’t just amperage. Cut quality, consumable life, duty cycle, and long-term reliability separate the tiers. Here’s how to make the right choice.
Step 1: Determine Your Cut Thickness
Every plasma cutter has two thickness ratings that matter:
Rated cut (clean cut): The maximum thickness the machine cuts at full speed with good edge quality, minimal dross, and acceptable bevel angle (typically under 3 degrees). This is the thickness you can cut all day with production-quality results.
Severance cut (max cut): The absolute maximum thickness the machine can get through, usually at slow speed with heavy dross, significant bevel, and poor edge quality. Useful for demolition and scrap but not fabrication.
The rated cut is the number to shop by. Severance cut is an emergency capability, not a daily operating point.
| Machine Class | Amperage | Rated Cut (Steel) | Severance Cut | Typical Use |
|---|---|---|---|---|
| Light Duty | 25-30A | 1/4" (6mm) | 3/8" (10mm) | Sheet metal, auto body, HVAC |
| Medium Duty | 40-45A | 1/2"-5/8" (13-16mm) | 3/4"-7/8" (19-22mm) | Small fab shop, maintenance |
| Heavy Duty | 60-65A | 3/4"-7/8" (19-22mm) | 1"-1-1/4" (25-32mm) | Structural, heavy fabrication |
| Industrial | 80-105A | 1"-1-1/4" (25-32mm) | 1-1/2"-1-3/4" (38-44mm) | Production cutting, CNC tables |
For thickness-specific amperage charts, see plasma cutting thickness chart.
Step 2: Choose Input Power
Plasma cutters come in three input power categories:
120V (110V): Limited to about 25-30A output. Cuts up to 1/4" clean. Good for sheet metal work and light cutting. Plugs into a standard household outlet. Some dual-voltage machines can also run on 120V at reduced output.
240V (220V/230V): The standard for 40-65A machines. Requires a dedicated 240V outlet (30A or 50A circuit depending on the machine). This is what most home shops and small fab operations install.
Dual-voltage (120V/240V): Runs on either input. On 120V, output is reduced (typically 25-30A). On 240V, full output is available. Maximum flexibility for shops with both outlet types or for field work.
Three-phase (208V/460V/575V): Industrial machines for production environments. More efficient at high amperages, lower input current draw, and typically paired with CNC tables. Not relevant for most small shops.
Input Current and Circuit Sizing
The input current draw determines what circuit breaker and wiring you need:
| Machine Output | Input Voltage | Approximate Input Amps | Minimum Circuit Breaker |
|---|---|---|---|
| 30A output | 240V single phase | 18-22A | 30A |
| 45A output | 240V single phase | 25-32A | 40A |
| 65A output | 240V single phase | 38-48A | 50A |
| 85A output | 240V single phase | 48-60A | 60A |
Step 3: Pilot Arc vs Contact Start
Pilot arc generates a small arc between the electrode and nozzle inside the torch. When you bring the torch near the workpiece, this pilot arc transfers to the metal and initiates the cutting arc. No physical contact with the workpiece is needed.
Contact start (touch start) requires pressing the torch tip against the workpiece to create a short circuit that initiates the arc. Simple and reliable, but limited.
Pilot arc is worth the extra cost for several reasons:
- Cleaner cut starts with no metal contamination on the tip
- Cuts expanded metal, grating, and perforated material where contact start fails
- Better for CNC applications where the torch doesn’t touch the work
- Less consumable wear on starts
- Can start a cut from the edge or in the middle of a plate (piercing)
Budget machines under $400 typically use contact start. Anything above that price point should have pilot arc. Don’t compromise on this feature.
Step 4: Evaluate Duty Cycle
Duty cycle is the percentage of a 10-minute period the machine can cut at rated output before needing to cool down. A 60% duty cycle at 45A means 6 minutes of cutting and 4 minutes of cooling per 10-minute period.
For handheld cutting, 50-60% duty cycle at rated output is adequate. You naturally pause between cuts to reposition, mark lines, and set up the next cut. Unless you’re running a CNC table making continuous cuts, you rarely hit the duty cycle limit.
For CNC applications, look for 100% duty cycle at the amperage you’ll actually use. Many machines offer 100% duty cycle at a reduced amperage (for example, 100% at 35A on a 45A machine). This is the continuous cutting capacity.
Step 5: Air Supply Requirements
Compressed air is the most common plasma gas for shop machines. The air must be clean and dry. Moisture, oil, and particles destroy consumables and degrade cut quality.
Typical requirements by machine class:
| Machine Class | Air Pressure (PSI) | Air Flow (CFM) | Minimum Compressor Size |
|---|---|---|---|
| 30A | 65-75 PSI | 3.5-4.5 CFM | 20 gal, 5 CFM @ 90 PSI |
| 45A | 75-90 PSI | 5-6 CFM | 30 gal, 6.5 CFM @ 90 PSI |
| 65A | 80-90 PSI | 6-7 CFM | 60 gal, 8+ CFM @ 90 PSI |
| 85A+ | 85-90 PSI | 7-9 CFM | 80 gal, 10+ CFM @ 90 PSI |
For detailed air compressor sizing, see plasma cutter air compressor requirements.
Step 6: Consider Consumable Availability and Cost
Plasma torch consumables (electrode, nozzle, swirl ring, shield cup) are wear items that need regular replacement. Before buying a machine, check:
Availability: Are consumables stocked locally, or do you have to order online and wait for shipping? Major brands (Hypertherm, Miller, Lincoln) have consumables available at most welding supply stores. Budget import brands may require online ordering with shipping from overseas.
Cost per set: A complete consumable set for a Hypertherm Powermax45 runs about $15-25. Budget machine consumable sets run $5-12. But budget consumables often last half as long, so the cost per hour of cutting may be similar.
Aftermarket options: Hypertherm-compatible aftermarket consumables are widely available at 30-50% less than OEM. Quality varies. Some aftermarket tips cut nearly as well as OEM. Others wear out quickly. For more on consumable selection and life, see plasma cutter consumables guide.
Feature Checklist
Beyond the core specifications, these features add value:
Built-in air filter/regulator: Removes moisture and sets pressure without external equipment. Most mid-range and higher machines include this.
Post-flow timer: Keeps air flowing after the arc stops to cool the torch and consumables. Extends consumable life. Standard on all quality machines.
Drag-tip (contact cutting) capability: Lets you rest the torch cup on the workpiece while cutting for straighter freehand cuts. Most modern machines support this.
Removable torch: Allows torch replacement when the cable wears out, or switching to a machine torch for CNC use. Fixed torches on budget machines mean replacing the entire torch assembly.
CNC interface port: A connection for CNC table control (usually a small multi-pin connector or CPC port). Essential if you plan to use the machine on a CNC table now or later.
Gouging capability: Some higher-amperage machines can gouge metal for weld prep or defect removal using a special gouging tip. Not available on all machines.
Price Tiers and What to Expect
Budget: $200-500
Chinese import brands, some rebranded as US-sounding names. Typically 30-50A, contact start, basic controls. Cut quality is acceptable for hobby use. Consumable availability can be spotty. Duty cycle ratings may be optimistic. Expect 2-5 years of occasional use before issues.
Mid-Range: $500-1,500
Established brands with 40-65A output, pilot arc, digital displays, built-in air filters. This tier includes machines from Hobart, Eastwood, YesWelder, and Everlast. Adequate for small fab shops and serious hobbyists. Consumables available online and sometimes locally. Good value for non-production use.
Professional: $1,500-3,500
Hypertherm Powermax, Miller Spectrum, Lincoln Tomahawk lines. 45-85A, pilot arc, excellent cut quality, long consumable life, strong duty cycles. Industrial build quality and full warranty support. Consumables available everywhere. These machines last 10-20+ years in professional environments. For brand comparisons, see Hypertherm vs Miller vs Lincoln plasma.
Industrial: $3,500-8,000+
Hypertherm Powermax 85/105/125, ESAB 0558012698 series, Lincoln FlexCut. High-amperage machines for production cutting and CNC tables. CNC interface standard. Multiple torch options. Designed for daily industrial use.
Matching Machine to Application
Auto body and sheet metal: 30A machine on 120V or dual-voltage. Light, portable, handles 16 gauge to 1/4" easily. Budget or mid-range tier.
Home shop and hobby fabrication: 45A on 240V with pilot arc. Cuts everything you’re likely to encounter in a home shop. Mid-range tier.
Small fabrication shop: 65A on 240V from a professional brand. Handles structural steel, plate work, and pipe. Long consumable life and reliable daily use justify the professional price.
CNC plasma table: Match the machine amperage to your typical cut thickness with 20-30% headroom. A CNC table cutting mostly 1/4" to 1/2" steel does well with a 65A machine. Ensure the machine has a CNC interface (machine torch connection and remote start/stop). For CNC vs handheld details, see handheld vs CNC plasma cutting.
Field and construction: Portability matters. A compact 45A inverter plasma cutter weighing 25-35 lbs handles most field cutting. Dual-voltage input is a plus for varying job site power availability.
Common Buying Mistakes
Buying based on severance cut, not rated cut. That “cuts 1 inch” headline on a 45A machine means severance cut. The actual clean cut is 5/8". Buy for the rated cut thickness.
Ignoring air quality. A plasma cutter without clean, dry air cuts poorly and eats consumables. Budget for a proper inline filter and moisture separator even if the machine has a built-in filter.
Skipping pilot arc to save money. Contact start works but limits what you can cut and wears consumables faster. The $100-200 savings isn’t worth the frustration.
Undersizing the compressor. Your compressor must deliver the required CFM continuously at the required PSI. A small compressor that hits the required CFM intermittently will starve the plasma cutter, dropping air pressure mid-cut and destroying consumables.
Not checking the return policy. Buy from a dealer with a reasonable return or exchange policy. If the machine doesn’t cut as expected, you want options.