You might be wondering, just how big is a newton?

The Pull of Gravity on One Kilogram

Lets start with one kilogram of mass.  This is typically the largest mass object in a mass set that you might find in a regular physics classroom.

If we use Newton’s Second Law, and the acceleration due to gravity…

\(\color{black}{\Sigma \vec{F} =m \vec{a}}\)


\(\color{black}{\Sigma \vec{F}_g =m \vec{g}}\)


\(\color{black}{{F}_g =1.0 \text{ kg} \cdot 9.8 \text{ m/s²}}\)


\(\color{black}{{F}_g = 9.8 \text{ kg} \cdot \text{m/s²}}\)


This means that 1 kg of mass weighs roughly 10 newtons.  (In practice use 9.8 N, but 10 is slightly easier for rough estimates.)

How Big is a Newton?

It turns out that  9.8 N is equivalent to 2.203 lb of force.  (Most people use 2.2 lb or 2.20 lb for this conversion.)

To convert between pounds and newtons then, use 9.8 N = 2.2 lb as your conversion ratio.  As we’ve seen before, we will enter this as a fraction, with the appropriate unit on the top or bottom to help us cancel things out properly.  Applying our unit conversion system,

\(\color{black}{1.0 \text{ N} = 1.0 \text{ N} \cdot \frac{2.2 \text{ lb}}{9.8 \text{ N}}}\)


This gives us…

\(\color{black}{1.0 \text{ N} = 0.2245 \text{ lb}}\)


So 1 N is equivalent to just about 1/4 of a pound (roughly).  If we add just a little bit of mass to the 1.0 N object, we can get up to the quarter pound.  In fact, the way I get a feel for a newton is by thinking of a QuarterPounder from McDonalds.  If we cook down the 1/4 lb starting weight, we get about 1 N of weight.

Perhaps you can think of a healthier alternative way to remember just how big is a newton.