Difference Between Similar Terms and Objects

Differences Between LB and LBF


If you have reached this article, then you are certainly looking for answers to the differences between “lb” and “lbf.”  To start with the discussion, let us be clear that we are talking about pound (lb) and pound force (lbf).  Thus, let us start comparing and differentiating these two units to clear away any confusion.

First, let us look at lb or pound.  A pound is a unit measurement of weight used in systems of measurement.  This is used by the United States’ unit of measurement.  Therefore, if you are talking about or have heard a pound, or 1 lb, then it is just equivalent to 0.45359237 kg, or kilograms, approximately.

Historically, “lb,” or pound, is derived from libra pondo, a Latin phrase that means “a pound weight.”  To make it universal and official, a pound, or lb, is translated as an avoirdupois pound equivalent to the above-mentioned kilogram equivalent.  This is necessary to differentiate and compare the units used in different parts of the world.

Now, let us take a look at “lbf” or pound force.  An lbf, or a pound force, is the gravitational force exerted by a matter on the surface of the Earth.  Thus, it is the force exerted by the mass of one avoirdupois pound.  Thus, 1 lbf, or one pound force, can be measured or converted in Newtons. For example, 1 lbf = 0.45359237 kg × 9.80665 m/s² = 4.448 N, or one pound force is equivalent to the product of 1 avoirdupois pound and the force which is equivalent to the mass multiplied by the acceleration due to gravity.

If you would like to delve deeper into the derivation of 1 pound force, then let’s do it.  A pound force is equivalent to the product of 1 pound or 1 lbm (one avoirdupois pound) and the gravitational field, gn.  In figures it looks like this, 1 lbm x 32.174049 ft/s2, or equivalent to 32.174049 ft.lbm/s2.  Thus if we convert it to “N,” or Newtons, then it is just 1 lbf = 0.45359237 kg x 9.80665m/s2 = 4.4482216152605 N.  We just multiplied the avoirdupois pound to the standard gravity in metric measurement.

Take note, we are talking about a measurement of force, not mass, because we are measuring the amount of force exerted by the weight of a thing on the Earth’s surface.  This is worth taking note of because a measurement of mass on Earth is not necessarily the same in measurement when in space.

Basically, when we talk about lb (pound) and lbf (pound force), we are talking about the same apple.  A pound can be stated as a pound force, too, informally, because it measures the same force, which is the force exerted by the mass of a matter on the surface of the Earth.

What is very confusing about it is the extra “f” on the symbol “lbf.”  Actually, a pound is a force, not a measurement of mass.  This is where the line gets really blurry and confusing.  We are so used to thinking and using “pound” as “mass,” but the main defining thing about it is it is not a measurement of just weight but the force of a matter that is exerted on Earth or Earth’s gravity.  We have to really understand the difference and definition of it because a pound in the sea is not a pound on Earth.  Or a pound in space is not a pound on Earth.  The main difference is gravity.  The gravitational pull makes the difference on the force; thus if we have to measure, we ought to use the gravitational pull on Earth.


  1. “Lbf” refers to the gravitational force placed by a matter on the Earth’s surface, while “lb” deals with the measurement of force.
  2. A pound force equals the product of 1 pound and the gravitational field.
  3. “Lb” and “lbf” are basically similar with each other since they both involve the same force.

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  1. You say a pound (lb) is equal to a weight and equal to some number of kilograms. A kilogram measures mass. Thus a pound cannot be equal to a number of kilograms.

  2. Lb = Mass
    Lbf = Force applied (like pushing) or weight (gravity)

    It happens that Lb = Lbf on Earth but not on any other celestial body in the solar system.

  3. In your summary i think there is an unfortunate typo.
    In point 1, last line should read “whilst lb deals with the measurement of mass”.

  4. Abnormally described the things. Instead of filling the garbage you need directly to write the relation between lbf and lb. Remove your post from the site in order to misdirect a person from correct result to GARBAGE.

  5. You are all a little off. lbf is often used in terms of towing. If you are simply lifting something off the ground they are equal, but pulling 1000 lbs of cinder blocks is very different based on whether you are pulling it on a trailer or a sled, or even a sled on ice vs a sled over gravel. Or consider moving a safe – a 700 lb safe is nearly impossible to move for a single man, but put it on a dolly (which technically adds a few lbs of weight for the dolly) and it’s quite doable… it takes “fewer lbs of force” to move it.

    • You, I trust to answer this. I do understand that the formula is available… but I need a little help.
      If an item has a capacity or strength of x, identified in kn. What is it’s actually weight capacity, ie: I weigh 240 pounds, and the item is a roller for a zip line. Thank you in advance for any assistance.

  6. [Corrected]Summary:

    1.“Lbf” refers to the gravitational force placed by a matter on the Earth’s surface, while “lb” deals with the measurement of force on a matter on the Earth’s surface.

    2. A pound-force(lbf) equals the product of 1 pound-mass(lbm) and the gravitational field. On Earth: 1 lbf = 1 ‘pound'(weight)(on a spring scale) = 1 lbm x 32 ft/s^2

    3.“Lb” and “lbf” are basically similar with each other since they both involve the same force (Earth gravity).

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