Free Tools
Industrial Gas Calculators
Quick answers for sizing and buying gas equipment. Pick the question you need answered.
Cylinder & Tube Capacity
How much gas does this cylinder, tube or vessel hold?
Enter the water volume and fill pressure — get the gas capacity in SCF for every common gas.
Open calculatorVessel Sizing
What size vessel do I need for this much gas?
Enter how much gas you need, the gas and the pressure — get the water volume to look for.
Open calculatorBuilt on real-gas physics, not shortcuts
Gas doesn't compress in a straight line as pressure rises — every gas packs differently, and the gap between the simple “pressure ÷ 14.7” estimate and reality grows the higher the pressure goes. These calculators are built from NIST reference equations of state, verified against hundreds of reference points, so the numbers hold up at the pressures the industrial gas and cryogenic world actually works at — not just at the easy, low-pressure cases.
Every calculator here runs on the server, not in your browser, is free with no account required, and says plainly what it's built on and where its limits are — each page links to the real sources behind its numbers.
Frequently Asked Questions
Common questions
Which calculator do I need?
If you have a vessel and want to know how much gas it holds, use Cylinder & Tube Capacity. If you know how much gas you need and want to know what size vessel to buy, use Vessel Sizing — it's the same math run in reverse. If you're sizing an ambient vaporizer for a nitrogen flow rate, use Ambient Vaporizer Sizing.
Why use a real-gas calculator instead of just dividing pressure by 14.7?
That simple ratio assumes gas compresses in a perfectly straight line with pressure, which real gases don't — each one packs differently as pressure rises. The gap between the simple estimate and the real number grows with pressure and can run several percent or more at high pressure. These calculators account for that directly instead of using the shortcut.
How accurate are these calculators?
The gas-law calculators (Cylinder & Tube Capacity, Vessel Sizing) are built from NIST reference equations of state and verified against hundreds of reference points — typically within a tenth of a percent. The vaporizer calculator is different: it's built from a manufacturer's published capacity table rather than a universal physics formula, and says plainly where its limits are. Each calculator's own page explains exactly what it's built on.
Are these free? Do I need an account?
Free, no account required. There's a fair-use rate limit to keep the tools responsive for everyone; signing in raises that limit.
Can I use these if I'm not buying from Metal Mountain?
Yes — they're general physics and sizing tools, useful regardless of where you buy your equipment or gas.
Need help finding the right equipment?
Tell us what you need — we'll help you find it.