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The hockey stick graph

A long flat handle, then a sharp blade. Where the shape gets its name, why it persuades, and how to read or draw one honestly.

2 min readSample
Chart typeLine chartShows how a measure changes across an ordered, continuous axis, usually time.

Sample article: the structure is final, the copy is a first draft to replace with yours.

A hockey stick graph is not a chart type of its own. It is a line chart whose data has a particular shape: a long, nearly flat stretch (the handle) followed by a sudden, steep rise (the blade). The shape is so recognisable that it earned a name, and so persuasive that it deserves a second look.

Where the name comes from

The term became famous through climate science. In 1998 and 1999, Michael Mann, Raymond Bradley and Malcolm Hughes published reconstructions of Northern Hemisphere temperatures going back centuries: a long period of small variation, then a sharp rise in the twentieth century. The climatologist Jerry Mahlman nicknamed the curve the "hockey stick", and it became one of the most discussed charts in science.

In business, "hockey stick growth" usually describes the revenue line in a pitch deck or a sales forecast: flat for a while, then a steep climb that is almost always just about to begin.

Try the shape

Data
Vertical axis

Growth is the same 30% every year, yet the last 5 of the 20 years shown hold 74% of the whole rise. Move the start: the “take-off” moves with the window.

Synthetic data generated from a formula.

Three questions before you believe one

  1. Is it a change, or just compounding? Anything that grows by a steady percentage looks flat, then explosive, on a linear axis. On a logarithmic axis the same series is a straight line. If the log view has no knee, nothing special happened at the "take-off".
  2. Where does the axis start? Moving the first period changes where the blade seems to begin. A handle can be made longer or shorter just by choosing the window.
  3. Which part actually happened? In plans and pitch decks the blade is often a projection. Actuals and forecast should look different, solid against dashed, and the forecast should carry a range that widens with time.

How to draw one honestly

  • Use a line chart, with time on the horizontal axis in even steps.
  • Mark where actuals end and projections begin, and show the range of outcomes rather than a single line.
  • When growth is exponential, offer a log-scale view, or chart the growth rate itself.
  • Annotate the knee with its cause if there is one. If there isn't, don't point at it.
  • Start the vertical axis at zero for totals, so the flatness of the handle is real and not a crop.