Buoy height vs wave face: why 4 ft can be over your head

Two different measurements

A buoy floats in deep water and measures the swell as it passes. Its height is the significant wave height: the average of the biggest third of the waves. The biggest sets are taller than that, often by half again or more.

Surfers measure the face: from the trough to the lip, on the front of the wave as it breaks. That is the number on a BarrelFare forecast.

Why the face is bigger

When swell reaches shallow water, it slows down and the energy piles up into a taller wave. A longer period piles up more. A reef or a deep channel can focus the swell onto one spot, so a reef break often reads bigger than the beach next to it on the same swell.

Try it

One buoy reading, three real breaks. Each break's focus factor comes from BarrelFare's spot data.

Where you see it on BarrelFare

The forecast shows the face at each break, not the buoy number. Tap a day on a spot page to see the swells behind it: their buoy height, period and direction.

How to read a surf report and forecast