Surfboard volume calculator

Find the volume range that suits your weight, your surfing and the kind of board you want, see a typical board of that size, and check whether a board you own or are eyeing fits.

Inputs

Without a wetsuit. In a thick wetsuit or poor waves, aim for the top of your range.

Be honest. Fitness and how often you surf count as much as ability.

Board type

Recommended volume

33.5L

Range 30.8–36.2 L

For a 170 lb intermediate surfer on a performance shortboard.

Guild factor
0.40–0.47 L per kg
Typical shortboard at 33.5 L
6′2″ × 19 7/8″ × 2 11/16″
Your volume range, and a performance shortboard that fits it
Typical performance shortboard at 33.5 L6′2″ × 19 7/8″ × 2 11/16″0′1′2′3′4′5′6′7′8′9′10′Your range 30.8–36.2 L20 L25 L30 L35 L40 L45 L

A 170 lb intermediate surfer on a performance shortboard should look for about 30.8–36.2 L of volume (0.40–0.47 L per kg). A typical performance shortboard at 33.5 L measures about 6′2″ × 19 7/8″ × 2 11/16″.

How it works

Volume is how much space a board takes up, in litres. It sets how high the board floats you, and so how fast you paddle and how early you catch waves. The right amount depends mostly on your weight and your surfing:

shortboard range = weight (kg) × guild factor for your skill × weight adjustment
guild factor:  beginner 0.60–0.80    beginner to intermediate 0.48–0.58
intermediate 0.40–0.47    intermediate to advanced 0.36–0.40
advanced 0.34–0.38
weight adjustment: +1.2% per kg under 62 kg, +0.8% per kg over 98 kg
board type:    hybrid × 1.05    fish × 1.10    mid-length + 13 L (at 75 kg)
longboard at least 0.75–1.00 L per kg
board volume from its size ≈ length × width × thickness × shape factor
  • Guild factor ranges come from Lost Surfboards’ published ratios and were fitted so that both board makers’ charts land inside them: 196 of the 213 values in Firewire’s and Surftech’s tables fall in our ranges, and none is more than 3% outside.
  • Light and heavy surfers. Both charts give kids and light adults proportionally more volume, and surfers over about 215 lb a little more too. The weight adjustment follows them.
  • Board type. The ranges above are for a performance shortboard. Firewire suggests riding its hybrids on the high side of your range and a mid-length with about 13 L more than your shortboard. Longboards get their float from length, so the range rarely depends on skill.
  • Typical size is interpolated from Firewire’s stock size tables for that type of board.
  • Checking a board. If you know its litres, enter them. If not, the calculator estimates them from length × width × thickness (in cubic inches, × 0.0164 for litres) times a shape factor: 0.53 for a performance shortboard, 0.57 for a hybrid, 0.58 for a fish, 0.565 for a mid-length and 0.575 for a longboard. Those are the averages of Firewire’s and Torq’s stock boards of each type.

Worked example

A 170 lb (77.1 kg) intermediate surfer looking at shortboards:

  • Range: 77.1 × 0.40 = 30.8 L to 77.1 × 0.47 = 36.2 L, middle 33.5 L. Firewire’s chart says 33.8 L for 170 lb; Surftech’s says 33 L at 75 kg and 35 L at 80 kg.
  • A typical shortboard at 33.5 L is about 6′2″ × 19 7/8″ × 2 11/16″.
  • A 6′2″ × 20 1/4″ × 2 5/8″ board they already own: 74 × 20.25 × 2.625 = 3,934 in³ = 64.5 L of box, × 0.53 = about 34.2 L, inside the range.
  • The same surfer on a mid-length: add 0.173 L per kg (13.4 L), so 44.2–49.6 L, about a 7′2″ × 21 3/4″ × 2 11/16″.

Tips

  • Weigh yourself honestly, then be honest about how often you surf. Fitness and time in the water move you along the range as much as ability does. Two sessions a month? Aim for the top of your range.
  • Conditions move you along the range. Lost Surfboards suggests the low end in warm water and good waves, and the high end in poor or crowded surf or a thick wetsuit.
  • Small, weak waves want more volume; big, steep waves want less. That’s why many surfers own a fish or groveler with a few more litres than their shortboard, and a step-up for bigger days.
  • Volume isn’t everything. Two boards with the same litres can feel completely different: a wide, short board and a long, narrow one paddle and turn differently. Use volume to narrow the list, then compare outlines.

FAQ

What volume surfboard does a 170 lb intermediate surfer need?

About 31–36 litres on a performance shortboard. At 170 lb (77 kg), 0.40–0.47 litres per kilogram gives 30.8–36.2 L. Firewire's chart gives 33.8 L and Surftech's 33–35 L for the same surfer. On a mid-length it's about 44–50 L, and on a longboard 58–77 L.

What is the guild factor?

It's board litres divided by your weight in kilograms, named after shaper Whitney Guild, whose chart Lost Surfboards publishes. A 75 kg surfer on a 27 L board rides a guild factor of 0.36, which is where fit, advanced shortboarders sit. Beginners do better at 0.6 or more.

Does the kind of board change how much volume I need?

Yes. Fish and hybrids are ridden shorter and fuller, so they carry a few more litres than your shortboard. Firewire suggests about 13 L more for a mid-length. Longboards float everyone well, so their range depends on your weight more than your skill.

Is the volume from my board's dimensions accurate?

It's an estimate. Length × width × thickness overstates volume because the nose, tail and rails taper, so we multiply by a shape factor for each board type, taken from Firewire's and Torq's stock boards. Most stock boards land within 6%. If the maker publishes the litres, use that number instead.

Do epoxy and PU boards with the same litres float the same?

Not quite. Epoxy foam is more buoyant, so an epoxy board paddles like a bigger PU board. Degree 33 says its 9′ epoxy longboard (72.5 L) paddles like the same model at 9′6″ in PU. If you're moving from PU to epoxy, you can go a little smaller.

Sources

  1. Surfboard Volume Calculator (table by weight and experience level), Firewire Surfboards. Litres for 80–240 lb at five levels, Beginner to Advanced. Firewire's stock size tables (length, width, thickness and litres by model) and its Boss Up note, "roughly +13 liters more volume than your standard shortboard", are from its product pages.
  2. Surfboard Volume Guide, Surftech. Litres for 77–243 lb (35–110 kg) at three levels.
  3. Volume Calculator (guild factor), Lost Surfboards by Mayhem. Shortboard guild factor ranges by skill and fitness (.34–.50), and the ratios its team riders use.
  4. Model size charts (PG-R, Summer Fish, Mod Fish, Mod Fun, Longboard), Torq Surfboards. Dimensions and litres of stock boards, used with Firewire's to check the volume-from-dimensions estimate.
  5. What is Surfboard Volume?, Degree 33 Surfboards. Epoxy versus PU buoyancy at the same volume.
  6. Volume to Weight Ratios (Updated), Surf Simply. Typical volumes by board type (shortboard 25–35 L, 7 ft funboard 40–50 L, longboard 60–100 L).

Formula and sources last checked September 30, 2026. How we test formulas.

  • Wetsuit thickness by water temperatureWhat wetsuit thickness do you need? Enter the water temperature for the suit to buy (3/2, 4/3, 5/4 or 6/5) and whether you need boots, gloves or a hood.