🏄 Surfing Wave Calculator
Wave height conversions, energy & board sizing
Understanding Wave Measurements
Wave height is measured two ways that confuse everyone. The "face height" is what you see — the height of the wave from trough to crest as you ride it. The "Hawaiian scale" measures the back of the wave, which is roughly half the face height. When a Hawaiian surfer says "6-foot," they mean a wave with a 10-12 foot face. When a California surfer says "6-foot," they usually mean a 6-foot face. This calculator converts between both scales.
Swell period (the time between waves) matters as much as height. A 5-foot wave with a 15-second period carries far more energy than a 5-foot wave with an 8-second period. Longer periods mean the energy extends deeper underwater, creating more powerful, organized waves. Periods above 14 seconds are considered long-period ground swell — the most desirable for surfing. Periods below 9 seconds are wind swell — weaker, choppier, and less organized.