Flow Rate Converter

Standard vs actual flow (sccm, SLPM vs cm³/min, L/min)

Actual flow (cm³/min, L/min, CFM, m³/h) is the volume the gas really occupies at line conditions. Standard flow (sccm, SLPM) is the volume the same amount of gas would occupy at reference conditions, so it behaves like a mass flow. To convert, use Q_actual = Q_standard × (T_actual / T_ref) × (P_ref / P_actual) with absolute temperatures and pressures. Reference conditions vary between industries: 0 °C and 101.325 kPa (SEMI E12, "normal"), 20 °C and 101.325 kPa, or 21.1 °C (70 °F) and 14.696 psia. The converter lets you pick the reference.

Which gallon?

GPM here is the US gallon per minute (3.785411784 L/min). An imperial gallon per minute is about 20 % larger (4.54609 L/min).

Flow Rate unit definitions

cubic meter per second (m³/s)

The cubic metre per second (m³/s) is the SI unit of volumetric flow rate. Hydrologists call it the cumec.

cubic meter per hour (m³/h)

The cubic metre per hour (m³/h) is the volume in cubic metres that passes in one hour; 1 m³/h = 1/3600 m³/s.

liter per second (L/s)

The litre per second (L/s) is a volumetric flow rate of one litre each second, 10⁻³ m³/s.

liter per minute (L/min)

The litre per minute (L/min, LPM) is a flow of one litre each minute, 1/60 000 m³/s.

cubic centimeter per second (cm³/s)

The cubic centimetre per second (cm³/s, also cc/s or mL/s) is a flow of one cubic centimetre each second, 10⁻⁶ m³/s.

cubic centimeter per minute (cm³/min)

The cubic centimetre per minute (cm³/min, cc/min, mL/min) is an actual volumetric flow of one cubic centimetre each minute. It is not the same as sccm, which is referenced to standard conditions.

sccm (sccm)

The standard cubic centimetre per minute (sccm) is the gas flow that would occupy one cubic centimetre per minute at standard reference conditions. It is effectively a mass flow, because it does not change with line pressure or temperature. Reference: Standard flow: volume the gas would occupy at the standard reference conditions (default 0 °C, 101.325 kPa). Converting to actual flow needs the actual temperature and pressure.

SLPM (SLPM)

The standard litre per minute (SLPM, also SLM; written NL/min when the reference is "normal" conditions) is the gas flow that would occupy one litre per minute at standard reference conditions. 1 SLPM = 1000 sccm. Reference: Standard flow: volume the gas would occupy at the standard reference conditions (default 0 °C, 101.325 kPa). Converting to actual flow needs the actual temperature and pressure.

cubic foot per minute (CFM)

The cubic foot per minute (CFM, ft³/min) is a flow of one cubic foot each minute, exactly 4.719474432 × 10⁻⁴ m³/s (about 1.699 m³/h).

US gallon per minute (GPM)

The US gallon per minute (GPM) is a flow of one US liquid gallon (231 in³) each minute, exactly 6.30901964 × 10⁻⁵ m³/s (about 3.785 L/min).

All flow rate conversions

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Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures.
• SEMI E12 Guide for Standard Temperature and Pressure Used in the Measurement of Mass Flow, SEMI.
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology.
• ISO 6358-1:2013 Pneumatic fluid power — Determination of flow-rate characteristics of components using compressible fluids, International Organization for Standardization.

Last reviewed: 2026-10-15.