The growth in coronavirus cases has followed a similar pattern around the world. Left unchecked, the virus spreads in a predictable way, with each day’s count increasing by a reliable percentage over the day before. In mathematics, this pattern is known as exponential growth.
This speed is measured by calculating how long it takes for total cases to double. In the early days of the pandemic, this was one of the most closely watched metrics. As growth has slowed, it’s become less useful, but The Times is preserving its charts tracking the numbers here. For a more complete view of the state’s status, you should visit our main coronavirus tracker.
The statewide trend
Looking at the last seven days of data, the number of cases in California is now on pace to double every 63.7 days.
Charts tracking exponential growth, like the one below, are plotted on a logarithmic scale to adjust for the rapid rise in values. A good sign is when a line flattens, which indicates that increases are slowing.
The trend by county
To gauge recent trends, The Times tracks the doubling time in all 58 counties with the last seven days of data.
This chart tracks cumulative cases after each county confirmed its 10th case. Compare the slope of a county's curve to the slope of the guide lines to estimate its doubling rate at any point.