4 min read

Mental Yardsticks

How can we convey numerical data effectively?
Mental Yardsticks
Photo by eskay lim / Unsplash


  • When communicating numbers, compare them to known quantities: mental yardsticks.
  • Use comparables familiar to your audience and relevant to the topic.
  • Use visual comparisons where possible.
  • Know mental yardsticks across a wide variety of domains. See examples below.


I once tried explaining the absolute risk of developing a disease to someone at a party, then I realized why I was having a hard time getting the point across. They didn't have the same mental yardsticks that I did. All measurement is relative: we define the magnitude of something in terms of a defined unit. If we don't share the same units and benchmarks, then it's like someone saying that they normally drive at 294,171 Macedonian cubits per hour on the freeway and gosh darn it, drivers are way too slow around here.

So I've since learned to communicate the magnitude of things using comparables that are familiar to my audience. To aid that, here's a list of benchmarks by domain. I plan to add to them over time.

(Alternative pithy formulations of this post: know your numbers; compare relatively rather than absolutely; have mental meter-sticks)


You probably already use mental yardsticks all the time when deciding what to purchase. "Is this worth the cost of N many of these? Would I rather have X?"

  • The cost of a cup of coffee
  • The cost of a lovely dinner and musical
  • The price of a 2-week trip to Southeast Asia
  • Your monthly rent/mortgage payment
  • Your monthly/yearly income
  • The cost of your house

Pro-tip: WolframAlpha lets you compare the inflation-adjusted costs of items over time: "Current value of $100 in 1919 dollars".


This is my favorite thing to analyze quantitatively, and it's best done through micromorts, where 1 micromort is a 1-in-a-million chance of dying (1/10,000 of a percent). Your Local Epidemiologist gives this great example table:

micromorts.rip maintains a handy table of micromort values for different activities.


From the CDC, here are the rates of the leading causes of death in the US as of 2021 (the data analysis lags a few years) per 100,000 people:

Here's the absolute count of the number of people killed per year by these diseases:

  • Heart disease: 695,547
  • Cancer: 605,213
  • COVID-19: 416,893
  • Accidents (unintentional injuries): 224,935
  • Stroke (cerebrovascular diseases): 162,890
  • Chronic lower respiratory diseases: 142,342
  • Alzheimer’s disease: 119,399
  • Diabetes: 103,294
  • Chronic liver disease and cirrhosis : 56,585
  • Nephritis, nephrotic syndrome, and nephrosis: 54,358

The standard advice to eat a healthy diet, exercise regularly, get enough sleep, not drink too much alcohol, and remain up-to-date on your vaccines is given ad infinitum for a reason. The reward? Decades more with the people and activities you love most.

For a more detailed breakdown (by region, sex, age, etc.), see the CDC's WONDER tool, which is based on the latest provisional data. They also have a summary analysis of the finalized data, most recently available for 2020.

Looking at the global picture for mortality reveals interesting differences, e.g., the substantial health burden of malaria in western Africa and HIV/AIDS in southern Africa.


  • 1 meter = the distance traveled by light in 1/299,792,458 of a second
  • 1 yard = 3 feet = 0.9144 meters
  • 1 meter = 3.28 feet
  • An American football field = 100 yards or 120 yards (including the end zones)
  • A soccer (football) field/pitch: 90–120 meters
  • 1 mile: 1,609.344 meters ~= 1.6 kilometers (km)
  • Distance from New York City (NYC) to San Francisco (SF) = 2,565 miles
  • Earth's diameter = 7,926 miles (12,756 km)
  • Earth's circumference (at the equator) = 24,901 miles (40,075 km)
  • Average distance from the Earth to the Sun = 1 astronomical unit (AU) ~= 150 million kilometers ~= 93 million miles
  • Distance traveled by light in a year = 1 light-year ~= 63,240 AU ~= 6 trillion miles
  • Nearest star system = Alpha Centauri, ~4.2 light-years away
  • Diameter of our Milky Way galaxy ~= 100,000 light-years

This is an area where visual diagrams are particularly helpful. My favorite as a kid was comparing the size of dinosaurs of course, e.g., these are different fossil specimens of Tyrannosaurus rex:

Or ships vs. buildings:

For more size comparison fun, see Scale of the Universe on the web and Universe in a Nutshell on mobile.


  • 1 liter of water weighs 1 kilogram
  • 1 kilogram = 2.2 pounds (divide by 2 for a quick-and-dirty estimate)
  • 1 (short) ton = 2,000 pounds (this is what a "ton" usually means in the US)
  • 1 long/imperial ton = 2,240 pounds (what a "ton" is in the UK)
  • 1 (metric) tonne = 1,000 kilograms ~= 2,204 pounds
  • M1A2 SEPv2 Abrams main battle tank: 71.2 (short) tons (p. 37 here)

Appendix: Data Sources

Here are some of my favorite sources when I need data: