ThisCalculator

Everyday

How to Abbreviate Liters Per Minute (L/min)

Updated · Standard formula, shown below

This guide shows you the standard abbreviations for liters per minute, a unit of flow rate used in engineering, medicine, and industry. You’ll learn the correct symbols, when to use each one, and how to avoid common errors. No special tools are needed—just a basic understanding of metric units.

What You’ll Need

  • Basic knowledge of metric prefixes (like milli- and kilo-)
  • A style guide if you’re writing for a specific publication (optional)

Step-by-Step

  1. Start with the base unit for volume. The liter is abbreviated as L (capital L) or l (lowercase l). The capital L is preferred in many countries to avoid confusion with the number 1.
  2. Add the time unit. For “per minute,” use the slash symbol / followed by min. So the most common abbreviation is L/min.
  3. Use the lowercase l if required. Some style guides (like the International System of Units) accept l/min as an alternative. In the United States, the National Institute of Standards and Technology (NIST) recommends using the capital L, but lowercase is still common in many technical fields.
  4. Include a space before the unit if you’re writing it out. For example, “5 L/min” is correct, not “5L/min” (unless you’re following a specific style that omits spaces).
  5. Use the cubic meter variant for scientific work. The official SI unit for flow rate is cubic meters per second (m³/s), but liters per minute is widely used. When you need to convert, remember 1 L/min = 0.001 m³/min = 1.6667 × 10⁻⁵ m³/s.
  6. Handle submultiples and multiples. For smaller flows, use milliliters per minute (mL/min or ml/min). For larger flows, you might see cubic meters per hour (m³/h) or liters per hour (L/h). To convert L/min to mL/min, multiply by 1000.
  7. Use the abbreviation consistently. Once you pick a style (e.g., L/min or l/min), stick with it throughout your document. Don’t mix capital and lowercase unless a specific standard requires it.

Common Mistakes

  • Using “lpm” as an abbreviation. While “lpm” is sometimes used informally (especially in medical settings), it is not a standard symbol. The correct form is L/min or l/min.
  • Confusing L with the number 1. In some fonts, a lowercase l looks identical to the digit 1. That’s why the capital L is preferred in many contexts.
  • Omitting the slash. Writing “L min” or “Lmin” is incorrect. The slash indicates the division of volume by time.
  • Using “L/m” instead of “L/min.” The abbreviation “m” alone stands for meter, not minute. Always use “min” to avoid ambiguity.
  • Forgetting to convert units in calculations. If you’re using a formula that expects m³/s, you must convert L/min to m³/s first.

Tips

  • Check your audience’s conventions. Medical, automotive, and industrial fields may have specific preferences. For example, respiratory therapists often use L/min, while some European texts use l/min.
  • Use a space between the number and the unit. This follows the SI style and improves readability: “12 L/min” not “12L/min.”
  • When in doubt, spell it out. If you’re writing for a general audience, “liters per minute” is always clear.
  • Use the correct abbreviation for “per.” The slash (/) is standard. Avoid using “p” as in “Lpm.”

Troubleshooting

If your abbreviation isn’t recognized or causes confusion, try the following:

  • If someone reads “L/min” as “liters per meter,” clarify by writing “liters per minute” at least once in your text.
  • If your software auto-corrects “L/min” to something else, disable auto-formatting or use a non-breaking space between L and /min.
  • If you’re converting to SI units and getting unexpected results, double-check your conversion factor. 1 L = 0.001 m³, so 1 L/min = 0.001 m³/min. Divide by 60 to get m³/s.
  • If you’re unsure about capitalization, use the capital L. It’s the most widely accepted in English-speaking countries.

Frequently Asked Questions

Is “L/min” the same as “l/min”?

Yes, both represent liters per minute. The capital L is preferred by NIST and many international standards, but lowercase l is also acceptable.

How do I abbreviate liters per second?

The abbreviation is L/s (or l/s). For example, 2 liters per second is written as 2 L/s.

What is the SI unit for flow rate?

The SI unit is cubic meters per second (m³/s). Liters per minute is a non-SI unit that is still widely used in many applications.

Can I use “LPM” in medical contexts?

While “LPM” is sometimes used informally, the standard medical abbreviation is L/min. Always follow your institution’s style guide.

How do I convert L/min to mL/min?

Multiply the value by 1000. For example, 5 L/min = 5000 mL/min.

What does “NL/min” mean?

“NL/min” stands for normal liters per minute, a unit used for gas flow at standard conditions (0°C and 1 atm). It’s different from ordinary L/min, which doesn’t specify pressure and temperature.

Related

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.