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Gas Cylinder Duration Calculator - Welding Shielding Gas Run Time by Cylinder Size & Flow Rate

Estimate how long your argon, CO2, or mixed gas cylinder will last at any flow rate setting

Calculate welding shielding gas cylinder duration based on cylinder size and regulator flow rate. Select from standard cylinder sizes (R, T, S, Q, K, #4, #3, #2, #1, MC, and specialty sizes) for argon, CO2, 75/25 Ar/CO2, 90/10 Ar/CO2, tri-mix, and other common shielding gases. Enter your flowmeter setting in CFH (cubic feet per hour) or LPM (liters per minute) to see estimated run time in hours. Includes gas cost-per-hour calculations, cylinder comparison charts, and tips for optimizing gas usage to reduce waste.

Pro Tip: Most welders run their shielding gas flow rate too high. The textbook recommendation for MIG welding is 25-35 CFH for most applications, but many welders crank the flow to 50-60 CFH thinking more gas means better coverage. Above 35-40 CFH, turbulent flow actually pulls ambient air INTO the weld puddle, causing more porosity than lower flow rates. Check for gas leaks at every fitting - a slow leak at 5 CFH wastes an entire T-cylinder in about 50 hours. Soapy water on every connection saves hundreds of dollars per year in wasted gas.

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Compressed Gas Cylinder Duration Calculator
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How It Works

  1. Select Gas Type

    Choose your shielding gas: 100% argon, 100% CO2, 75/25 argon/CO2, 90/10 argon/CO2, 98/2 argon/O2, helium, or custom mix. Gas type affects the cylinder capacity because different gases have different densities and fill pressures.

  2. Choose Cylinder Size

    Select your cylinder size designation. Common sizes include: MC (10 cf), #2 (40 cf), #1 (80 cf), K (251 cf), T/S (330 cf), and high-pressure cylinders up to 485 cf. CO2 cylinders are rated in pounds (5, 10, 20, 35, 50, 75 lb) since CO2 is stored as a liquid.

  3. Enter Flow Rate

    Input your regulator or flowmeter setting in CFH (cubic feet per hour) or LPM (liters per minute). Typical MIG welding uses 25-40 CFH, TIG welding uses 15-25 CFH, and flux-core with dual shield uses 30-45 CFH.

  4. Review Duration and Cost

    See the estimated run time in hours and minutes, plus the gas cost per hour based on your cylinder refill price. The calculator also shows the cost per linear foot of weld at typical travel speeds.

  5. Compare Cylinder Options

    View a side-by-side comparison of different cylinder sizes showing duration, cost per hour, and cost per cubic foot to determine the most economical cylinder size for your shop's usage volume.

Built For

  • Welding shop managers estimating shielding gas costs for project bids and quotes
  • Fabrication shops determining optimal cylinder sizes based on daily consumption rates
  • Mobile welders selecting cylinder sizes that balance run time against truck weight limits
  • Welding instructors demonstrating gas consumption rates to students for cost awareness
  • Purchasing agents comparing gas costs between cylinder sizes and supplier pricing
  • Pipeline welders calculating gas requirements for remote field welding operations
  • Maintenance welders estimating whether their current cylinder will last through a repair job

Features & Capabilities

Standard Cylinder Database

Includes capacity data for all standard argon, CO2, helium, and mixed gas cylinder sizes used in North American welding supply. Covers high-pressure gas cylinders (rated in cubic feet at STP) and liquid CO2 cylinders (rated in pounds).

CO2 Liquid-to-Gas Conversion

Properly handles CO2 cylinder calculations using the liquid-to-gas expansion ratio of approximately 8.7 cubic feet per pound at standard conditions. A 50 lb CO2 cylinder yields roughly 435 cubic feet of gas, not a simple pressure-volume calculation.

Flow Rate Optimization Tips

Provides recommended flow rate ranges by welding process and material thickness. Flags when the entered flow rate is above the recommended range where turbulence degrades gas coverage, helping welders reduce waste.

Cost Analysis

Calculates cost per hour of welding, cost per cubic foot of gas, and monthly/annual gas budget based on estimated arc-on time. Compares cylinder sizes to show the cost advantage of larger cylinders for high-volume shops.

Leak Loss Estimator

Enter a suspected leak rate to see how much gas and money is lost per day, week, and month. Even a small fitting leak at 2-3 CFH costs hundreds of dollars annually and can empty a cylinder overnight.

Frequently Asked Questions

A standard T-cylinder contains approximately 330 cubic feet of argon at standard temperature and pressure. At a flow rate of 25 CFH, the cylinder will last about 13.2 hours of actual arc-on welding time. In practice, welders typically have 15-25% arc-on time during a shift, so a T-cylinder can last 2-4 working days for a production MIG welder depending on the job. Pre-flow, post-flow, and gas that flows while adjusting or positioning between welds also consume gas.
The most common causes of excessive gas consumption are: fitting leaks throughout the gas delivery system (even small leaks add up 24/7), flowmeter set higher than intended, pre-flow and post-flow settings too long, gas flowing while repositioning between welds, regulator not shutting off completely when the torch trigger is released, and wind or drafts in the welding area requiring higher flow rates. Check every connection with soapy water and ensure the solenoid valve in the wire feeder closes fully.
Generally yes. The cost per cubic foot of gas decreases with larger cylinder sizes because the fixed costs of cylinder handling, delivery, and fill labor are spread across more gas. A T-cylinder (330 cf) typically costs 30-50% less per cubic foot than a #1 cylinder (80 cf). However, factor in cylinder rental fees, demurrage charges, and whether your usage rate justifies the larger size. A cylinder sitting unused still accrues rental costs. For very high-volume shops, bulk liquid argon systems are the most economical option.
CO2 is stored as a liquid under pressure (approximately 830 PSI at 70°F), so cylinder capacity is rated in pounds of liquid, not cubic feet of gas. One pound of liquid CO2 produces approximately 8.7 cubic feet of gas at standard conditions. A 50 lb CO2 cylinder yields about 435 cubic feet of gas. At 35 CFH, this lasts about 12.4 hours. As the CO2 is drawn off, the cylinder pressure remains constant (about 830 PSI) until the last liquid evaporates, then pressure drops rapidly - this is normal, not a regulator problem.
Recommended flow rates for MIG (GMAW) welding vary by gas type and application. For short-circuit transfer with 75/25 Ar/CO2, use 25-30 CFH for general fabrication. For spray transfer with 90/10 Ar/CO2 or 98/2 Ar/O2, use 30-40 CFH. For 100% CO2, use 30-40 CFH. Higher flow rates do not improve coverage - above 40-45 CFH, turbulence draws ambient air into the gas shield. In windy conditions, use wind screens rather than increasing flow rate. Nozzle size also affects optimal flow: larger nozzles work better at lower CFH.
A regulator reduces cylinder pressure (2000-2500 PSI for argon) to a usable working pressure (typically 30-50 PSI). A flowmeter measures and controls the volumetric flow rate of gas (in CFH or LPM) leaving the regulator. Some devices combine both functions into a single regulator/flowmeter unit with a calibrated ball-in-tube or dial gauge. Flowmeters can be either direct-reading (rotameter tube) or pressure-compensating types. Pressure-compensating flowmeters are more accurate across a range of inlet pressures. Always read the rotameter at the center of the ball, not the top or bottom.
Disclaimer: Gas cylinder duration estimates are based on standard conditions (70°F, 14.7 PSIA). Actual duration varies with temperature, altitude, regulator accuracy, system leaks, and welding technique. CO2 calculations assume complete liquid-to-gas conversion. Always follow compressed gas safety practices per CGA P-1 and OSHA 1926.350. ToolGrit is not responsible for gas consumption estimates, welding quality, or compressed gas safety.

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