How to Measure Wave Height
As a surfer, you have probably noticed some differences and even controversy over determining the height of a wave. There is a trend towards underestimating wave heights to appear nonchalant. A famous example is one year at the Eddie Aikau Waimea Big Wave competition judges were asked how big the surf was, they hesitated and replied, "overhead." For those who aren't familiar with an Eddie, the waves need to be at least 20 ft. Despite people calling wave heights how they see them, and the machismo involved with claiming they are smaller, there is some rhyme and reason to this determining the height of a wave. Here are the three official methods to measure wave height.
Face Height Method
The Face Height scale is the most common method agreed upon by surf forecasters. It measures a wave from the trough (bottom of the wave) to the crest (top of the wave), determining the height by the surfable face. In many circumstances, surf forecasters will add in a body height comparison to be extra clear. These range from knee-high to triple overhead. A typical Surfline forecast would look like “ 4 ft faces at about shoulder high”. Here is the scale used by Surfline:
1' = ankle-shin high
2' = knee-thigh high
3' = waist-belly high
4' = chest-shoulder high
5' = head high
6' = 1 foot overhead
8' = 3'overhead
10' = 5' overhead or Double Overhead faces
12' = Double Overhead+ faces
15' = Triple Overhead faces
20' = It's just really big
Hawaiian Scale or Traditional Scale
The Hawaiian scale generally equates a wave height to about half or 2/3 of the Face Height measurement. This method, also known as the "from the back" measurement, looks at height based on the back of the wave instead of the face. For example, an 8 ft wave by the face height scale would be a 4 ft wave by the Hawaiian scale. The surf forecaster, Surfline, calls this the traditional scale and gives you the option to switch to this measurement in their settings.
Bascom Method
Invented by Oceanographer and Engineer William Newel Bascom, this method is the least common method of the three. It requires the measurer to stand on the beach and line up the wave crest to the horizon, then they must measure that point to the mean or average sea level. Though recognized as rational and fair, the Bascom method is generally considered an overestimation by most surfers' standards.
This table shows some examples of the differences between the wave heights.
Now that you understand how to measure wave height, it’s time to put that knowledge to the test and hit the waves. Remember to check out the Jamie O’Brien Surf App here for anytime, anywhere surfing.
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