How Are Waves Measured in Surfing? Face Height vs Hawaiian Scale

There is no single standard for measuring a surf wave, and that is why one surfer's "3 ft" can look like another surfer's "6 ft". Face height measures the front of the wave from trough to crest. The Hawaiian scale uses a much smaller number for the same wave. Body-based sizes like waist high and overhead compare the wave to a person. And the buoy figures in a surf report measure the swell out in open water, before it ever reaches a beach.

What is wave face height?

Face height is the vertical distance from the trough, the low point in front of the wave, up to the crest at the top of the face you ride. It is the most intuitive measurement because it describes the wall of water you actually see from the lineup. Many surf reports and forecasts describe surf in face height, and it is the measurement most beginners assume every report uses.

What is the Hawaiian scale?

The Hawaiian scale is a traditional way of calling wave size that produces much smaller numbers than face height. It is often described as measuring the back of the wave, and in practice a Hawaiian-scale call is usually about half the face height, so a "3 ft Hawaiian" wave can have a face around head high or more. There is no official conversion, and the call varies between surfers, which is part of why it confuses people.

The scale is common in Hawaii and used by some surfers elsewhere, often as a show of understatement. The practical lesson is the one in our guide to reading a surf report: check which scale a report uses before you trust the number.

What do knee high, waist high and overhead mean?

Body-based sizes compare the wave face to a surfer standing on a board, which makes them the easiest to picture and the hardest to argue about:

• Ankle to knee high: very small surf, mostly useful for longboards and learning.
• Waist to chest high: a fun everyday size for most surfers.
• Shoulder to head high: solid surf that needs real paddling and positioning.
• Overhead: the face is taller than the surfer.
• Double overhead: roughly twice the surfer's height, and serious surf.

What do the buoy numbers in a surf report measure?

Buoys measure swell in open water, usually reported as significant wave height, the average height of the highest one-third of waves, plus the period and direction. That is not the size of the waves at your beach. As swell moves into shallow water it slows and stands up, so breaking waves can be bigger than the buoy number, especially with a long swell period. A spot facing away from the swell, or shielded by a headland, can be far smaller.

Why do surf reports disagree on wave height?

Because they are often measuring different things. One report may use face height, another the Hawaiian scale, a third a modeled prediction from buoy data, and a person on the beach is estimating by eye. Add the fact that sets are bigger than the waves between them, and two honest reports can give numbers that differ by a factor of two. Our guide to how accurate surf reports are covers the rest of the gap.

The short version

Face height measures the front of the wave and is what most people picture. The Hawaiian scale gives a smaller number, often about half the face. Waist high and overhead compare the wave to a surfer. Buoy numbers measure open-ocean swell, not the waves at your beach. When a number matters, check which of these a report is using.