Gas quantities

Gas Unit Converter & Helium Calculator

Convert quantities with the gas, pressure basis and reference conditions clearly stated.

User guide

JavaScript is required for calculations. The method notes and gas quantities guide remain available below.

Helium quantity & price

Edit any amount or unit price. The other fields update automatically.

Quantity input Enter an amount Calculate from vessel

Metric gas-volume referencePrice currencyCurrency label only. No exchange-rate conversion.

Use a decimal point or comma, without thousands separators. Amount and price are independent inputs.

No amount or price entered.

SCF = ft³ at 60 °F and 101.325 kPa absolute. MCF = 1 000 SCF; MMCF = 1 000 000 SCF. Contract definitions may differ.

Your calculation

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Estimated massNo quantity yet

Gas equivalent No quantity yet

Total at your entered priceEnter quantity and price

Delivery state for RFQ

Engineering estimate only. Not a filling instruction, certificate of quantity or custody-transfer measurement.

Liquid litres are an equivalent at 0.12474 kg/L (-268.93 °C, 1.013 bar absolute), not liquid present in a gas vessel. Unit prices exclude liquefaction, losses, packaging, freight, duties and taxes.

Review and apply the quantity on the RFQ page. Prices are not passed to RFQ.

Method and source parameters

Pure helium model: CoolProp 8.0.0 HEOS, a bounded density grid. Liquid equivalent uses a separate state-specific density. No mixtures or enriched isotopes.

CoolProp helium model · Related NIST equation of state

Liquid helium quantity

Approximate density: 0.12474 kg/L at −268.93 °C and 1.013 bar absolute. Not the water capacity of a tank.

Liquid helium amountInput unit

Gas-equivalent reference conditions

This changes the volume equivalent, never the mass. The label “standard” alone is not a complete specification.

0 °C 15 °C 20 °C 60 °F

All presets: 101.325 kPa absolute (1 atm).
Gas equivalent uses the ideal-gas relation, Z = 1.

Result volume unit

Use 20.5 or 20,5 for a decimal; no thousands separators. For a three-place decimal such as 1.508, enter 1.5080.

Your calculation

Enter values and select Calculate. No result has been calculated.

Engineering estimate only. Not a filling instruction, certificate of quantity or custody-transfer measurement.

The RFQ form remains a separate review and submission step.

Know what the number represents

Three different volumes

Liquid litres describe liquid helium. Water capacity describes the inside of a vessel. Gas-equivalent volume describes a quantity at a stated temperature and absolute pressure. They are not interchangeable.

Read the guide to litres, kilograms, Nm³ and SCF.

Methods and boundaries

The separate other-gas mode uses the ideal-gas relation with Z = 1 and molar masses from CIAAW; argon assumes atmospheric isotopic composition. Helium quantity and vessel calculations use the real-gas model documented above. Liquid helium uses the state-specific density in Air Liquide's gas encyclopedia.

This tool does not determine safe filling limits, withdrawable gas, purity or isotope enrichment. For an enquiry, confirm packaging, quality requirements and the delivery basis.