# How to visualize one part per million

What does it mean to be one in a million? Not in the greeting card sense, in the scientific sense, where one part per million is a unit of measurement. Parts per million counts the number of units of one substance per one million units of another. It can measure concentrations when a small amount makes a big difference. For example, a concentration of just 35 ppm of carbon monoxide in the air is poisonous to us. We encounter measurements like this pretty often, but because it’s hard to conceptualize really large numbers, it’s difficult to wrap our brain around what one part per million really means.

So here are nine helpful ways to visualize it. If you had 11,363 pianos-worth of piano keys, one of those keys would be about one part per million. So would a single granule of sugar among 273 sugar cubes, one second in eleven and a half days, or four dots in the painting, “A Sunday Afternoon on the Island of La Grande Jatte.” Your bath tub’s capacity is about 60 gallons, so seven drops of ink would be one part per million.

The English version of the Harry Potter series has 1,084,170 words, which makes “hippogriff” on page 221 of “The Prisoner of Azkaban” a little less than one part per million. A million kernels of corn is about 1,250 ears, so one kernel in that truckload would be one part per million. There are 10 million bricks in the Empire State Building, so one part per million would be a pile of just ten. And finally, 100 people worked together to animate this video. Collectively, they have about 10 million hairs on their heads. Pluck ten of those hairs, and you have one in a million.