What surfboard volume do I need?
Type your weight and pick your surfing level. The surfboard volume calculator multiplies your weight in kilograms by the Guild Factor for that level and gives a board volume in liters, with the low end for warm water and good waves and the high end for poor waves or a thick wetsuit.
- Board volume (liters)
- 28.5
At 170 lb and a Guild Factor of 0.36 to 0.38 (middle 0.37), your surfboard volume is about 28.5 liters.
- Low end (liters)
- 27.8
- High end (liters)
- 29.3
- Weight in kg
- 77.1
- Guild Factor
- 0.36 to 0.38 (middle 0.37)
Board volume (liters): 28.5. At 170 lb and a Guild Factor of 0.36 to 0.38 (middle 0.37), your surfboard volume is about 28.5 liters.
How to calculate
Suggests a surfboard volume in liters from your weight and surfing level with the Guild Factor (weight in kg × factor), as a range and a middle value, or from a factor you choose.
Example with the default inputs (Your weight 170 lb, Your level Average to above-average, typical fitness (0.36–0.38)): At 170 lb and a Guild Factor of 0.36 to 0.38 (middle 0.37), your surfboard volume is about 28.5 liters.
Method: Board volume (liters) = weight (kg) × Guild Factor; the range uses the low and high factors of your level.
- One liter of board volume per kilogram is the Guild Factor’s unit: the factor is liters ÷ kilograms.
- The headline uses the middle of your level’s range.
- Typed values are read as the exact decimals typed, so a volume exactly half a tenth rounds up.
Worked examples
Each example is checked against the calculator on every build.
- Your weight 205 lb, Your level Weekend surfer, lower fitness (0.38–0.42) gives High end (liters) 39.054303, Low end (liters) 35.334846, Board volume (liters) 37.194574.Source: Lost Surfboards by Mayhem, What’s Your Guild Factor? Surfboard Volumes Explained (Guild Factor = volume in liters ÷ body weight in kg; 0.34–0.36 advanced and very fit, 0.36–0.38 typical fitness and average to above-average skill, 0.38–0.42 lower fitness and weekend surfers, 0.40–0.50 novices or extreme conditions; © Whitney Guild 2013), https://lostsurfboards.net/whats-your-guild-factor-surfboard-volumes-explained/ (retrieved 2026-10-02) (Matt Biolos: 205 lbs, 39 liters, GF .42)
- Your weight 154.3 lb, Your level Advanced, very fit (0.34–0.36) gives Low end (liters) 23.8, High end (liters) 25.2, Board volume (liters) 24.5, Guild Factor 0.34 to 0.36 (middle 0.35).Source: Lost Surfboards by Mayhem, What’s Your Guild Factor? Surfboard Volumes Explained (Guild Factor = volume in liters ÷ body weight in kg; 0.34–0.36 advanced and very fit, 0.36–0.38 typical fitness and average to above-average skill, 0.38–0.42 lower fitness and weekend surfers, 0.40–0.50 novices or extreme conditions; © Whitney Guild 2013), https://lostsurfboards.net/whats-your-guild-factor-surfboard-volumes-explained/ (retrieved 2026-10-02)
- Your weight 180 lb, Your level My own Guild Factor, Guild Factor 0.45 gives Board volume (liters) 36.740982, Low end (liters) 36.740982, Guild Factor 0.45.Source: Lost Surfboards by Mayhem, What’s Your Guild Factor? Surfboard Volumes Explained (Guild Factor = volume in liters ÷ body weight in kg; 0.34–0.36 advanced and very fit, 0.36–0.38 typical fitness and average to above-average skill, 0.38–0.42 lower fitness and weekend surfers, 0.40–0.50 novices or extreme conditions; © Whitney Guild 2013), https://lostsurfboards.net/whats-your-guild-factor-surfboard-volumes-explained/ (retrieved 2026-10-02)
How it works
- Convert your weight W to kilograms (1 lb = 0.45359237 kg).
- Take the Guild Factor range [g₁, g₂] of your level:
| Level | Guild Factor |
|---|---|
| Advanced, very fit | 0.34 to 0.36 |
| Average to above-average skill, typical fitness | 0.36 to 0.38 |
| Weekend surfer, lower fitness | 0.38 to 0.42 |
| Novice, or extreme conditions | 0.40 to 0.50 |
- Low end = W × g₁, high end = W × g₂, and the board volume (headline) = W × (g₁ + g₂) ÷ 2, all in liters.
- With your own Guild Factor g, all three are W × g.
Rules
- Weight above 0 and at most 500 kg; your own Guild Factor from 0.1 to 2.
- The weight is read as the exact decimal you typed in the unit you chose, so a volume exactly half a tenth rounds up.
Output format. Volumes and the weight in kg have 1 decimal. "Guild Factor" reads "0.36 to 0.38 (middle 0.37)", or the single factor you typed (such as 0.45), each written with up to 10 significant digits and no trailing zeros.
Worked examples by hand
A 205 lb weekend surfer. 205 × 0.45359237 = 92.986 kg. Low 92.986 × 0.38 = 35.3 L; high × 0.42 = 39.1 L (Lost's example: 39 liters at 0.42); middle × 0.40 = 37.2 L.
A 70 kg advanced surfer. 70 × 0.34 = 23.8 L, 70 × 0.36 = 25.2 L, middle 70 × 0.35 = 24.5 L.
A 180 lb surfer with a factor of 0.45. 180 lb = 81.647 kg; × 0.45 = 36.7 L.
Other questions people ask
How do I calculate surfboard volume?
Multiply your weight in kilograms by your Guild Factor. A 205 lb (93 kg) weekend surfer with a factor of 0.42 needs about 93 × 0.42 = 39 liters, which is the example Lost Surfboards gives for shaper Matt Biolos.
What is the Guild Factor?
A ratio devised by Whitney Guild: board volume in liters ÷ body weight in kilograms. His table runs from 0.34 to 0.36 for advanced, very fit surfers up to 0.40 to 0.50 for novices or extreme conditions. A higher factor means more foam for your weight.
Should I pick the low or the high end of my range?
The table's own advice: in warm water and good waves, the low end; in poor waves, crowded lineups or a thick wetsuit, the high end. The headline is the middle of the range.
Why does fitness matter, not just skill?
Paddling a smaller board takes strength and stamina. The Guild table groups surfers by fitness as well as skill, so a skilled surfer who surfs only on weekends is put at 0.38 to 0.42, not with the very fit advanced surfers.
Do I use my weight in pounds?
You can type pounds; the calculator converts to kilograms first (1 lb = 0.45359237 kg), because the Guild Factor is liters per kilogram. 170 lb is 77.1 kg, so at 0.37 that is about 28.5 liters.
Is volume the only thing that matters?
No. Length, width, thickness and where the foam sits change how a board paddles and turns. Two boards of the same volume can feel very different, so use the volume as a starting point when you compare boards.