Surfboard volume calculator
Enter your weight, in kilograms or pounds, and how you surf to get the volume in litres that fits you. Or enter a board's length, width and thickness to get the volume it holds. Either way, the used boards in Bali that match are one tap away.
Work out a volume
Surfboard volume chart
Volume is the size figure that decides whether a board paddles for you, and every level wants more of it as you get heavier. The chart shows the whole ladder at once. The table under it gives the figure for your weight: find your row and read across to how you surf.
| Rider weight | Beginner | Improver | Intermediate | Advanced | Pro |
|---|---|---|---|---|---|
| 40 kg 88 lb | 36 to 40 | 24 to 30 | 18 to 22 | 14 to 16 | 12.8 to 14 |
| 45 kg 99 lb | 40.5 to 45 | 27 to 33.8 | 20.3 to 24.8 | 15.7 to 18 | 14.4 to 15.7 |
| 50 kg 110 lb | 45 to 50 | 30 to 37.5 | 22.5 to 27.5 | 17.5 to 20 | 16 to 17.5 |
| 55 kg 121 lb | 49.5 to 55 | 33 to 41.3 | 24.8 to 30.3 | 19.3 to 22 | 17.6 to 19.3 |
| 60 kg 132 lb | 54 to 60 | 36 to 45 | 27 to 33 | 21 to 24 | 19.2 to 21 |
| 65 kg 143 lb | 58.5 to 65 | 39 to 48.8 | 29.3 to 35.8 | 22.8 to 26 | 20.8 to 22.8 |
| 70 kg 154 lb | 63 to 70 | 42 to 52.5 | 31.5 to 38.5 | 24.5 to 28 | 22.4 to 24.5 |
| 75 kg 165 lb | 67.5 to 75 | 45 to 56.3 | 33.8 to 41.3 | 26.3 to 30 | 24 to 26.3 |
| 80 kg 176 lb | 72 to 80 | 48 to 60 | 36 to 44 | 28 to 32 | 25.6 to 28 |
| 85 kg 187 lb | 76.5 to 85 | 51 to 63.8 | 38.3 to 46.8 | 29.7 to 34 | 27.2 to 29.7 |
| 90 kg 198 lb | 81 to 90 | 54 to 67.5 | 40.5 to 49.5 | 31.5 to 36 | 28.8 to 31.5 |
| 95 kg 209 lb | 85.5 to 95 | 57 to 71.3 | 42.8 to 52.3 | 33.3 to 38 | 30.4 to 33.3 |
| 100 kg 220 lb | 90 to 100 | 60 to 75 | 45 to 55 | 35 to 40 | 32 to 35 |
| 105 kg 231 lb | 94.5 to 105 | 63 to 78.8 | 47.3 to 57.8 | 36.8 to 42 | 33.6 to 36.8 |
| 110 kg 243 lb | 99 to 110 | 66 to 82.5 | 49.5 to 60.5 | 38.5 to 44 | 35.2 to 38.5 |
| 115 kg 254 lb | 103.5 to 115 | 69 to 86.3 | 51.8 to 63.3 | 40.3 to 46 | 36.8 to 40.3 |
| 120 kg 265 lb | 108 to 120 | 72 to 90 | 54 to 66 | 42 to 48 | 38.4 to 42 |
| 125 kg 276 lb | 112.5 to 125 | 75 to 93.8 | 56.3 to 68.8 | 43.8 to 50 | 40 to 43.8 |
| 130 kg 287 lb | 117 to 130 | 78 to 97.5 | 58.5 to 71.5 | 45.5 to 52 | 41.6 to 45.5 |
Litres with no shape adjustment. A fish takes 6 per cent more and a midlength 18 per cent more; every shape is in the table further down.
A beginner sits near their own body weight in litres. That surprises people who have been shown a shortboard table, which is where most of the bad advice on this subject comes from: those ratios were published for shortboards, and a beginner is not on one.
Which level are you?
Your level moves the answer more than anything else on the form. At 75 kg the middle of the improver range is 13 litres above the middle of the intermediate one, and that is the difference between a board that paddles and one that does not. Pick the line that describes what you do in the water now. The board that helps you improve is the one you catch waves on.
| Level | What it looks like | Litres per kg |
|---|---|---|
| Beginner | I am learning to stand up, mostly in whitewater, usually on a soft top | 0.9 to 1.0 |
| Improver | I can stand up most times and I am starting to ride along the open face | 0.6 to 0.75 |
| Intermediate | I catch unbroken waves, angle down the line and can turn off the bottom | 0.45 to 0.55 |
| Advanced | I link turns on most waves and surf a shortboard in decent surf | 0.35 to 0.4 |
| Pro | I surf anything, and I know what volume I want already | 0.32 to 0.35 |
Adjusting for the shape
A shortboard is the baseline. Shapes made for weak waves carry extra foam so they keep moving when the wave does not, a step-up carries a little more for the paddle into steep, fast ones, and the longer, wider shapes carry the most. The calculator adds the percentage in the middle column to your range.
| Shape | More litres | Makes sense from |
|---|---|---|
| Shortboard | The baseline | Intermediate |
| Twin fin | +5% | Intermediate |
| Groveler | +6% | Intermediate |
| Fish | +6% | Improver |
| Step-up | +8% | Advanced |
| Midlength | +18% | Improver |
| Soft top | +25% | Any level |
| Funboard | +30% | Any level |
Longboards, alaias and finless boards, stand-up paddleboards and foil boards are not in the table: length and outline pick those, and a litre figure for one would be made up.
The last column is the lowest level each shape suits. Pick a shape above your level and the calculator still gives you the litres, and tells you which board carries them.
How surfboard volume is calculated
Volume in litres is your weight in kilograms, times the litres per kilogram for your level, times the shape adjustment.
The litres-per-kilogram figure is what shapers call the Guild factor, after Whitney Guild. The tables published under that name were written for shortboards, and their lowest row is a novice on a shortboard. Read as a beginner table, they give someone learning roughly half the foam they need. A beginner belongs on a soft top or a funboard, so the beginner row here sits close to your own body weight in litres.
It is a starting range. Water temperature, how often you surf and what you are used to all move it, and nobody has ever regretted a litre too many at the end of a three-week trip.
Reading it backwards: who a board fits
Standing in front of a board that says 30 L on the stringer? Find the nearest volume and read across to your level: the weight range is who that board suits.
| Board | Beginner | Improver | Intermediate | Advanced | Pro |
|---|---|---|---|---|---|
| 25 L | — | 33 to 42 | 45 to 56 | 63 to 71 | 71 to 78 |
| 30 L | — | 40 to 50 | 55 to 67 | 75 to 86 | 86 to 94 |
| 35 L | 35 to 39 | 47 to 58 | 64 to 78 | 88 to 100 | 100 to 109 |
| 40 L | 40 to 44 | 53 to 67 | 73 to 89 | 100 to 114 | 114 to 125 |
| 45 L | 45 to 50 | 60 to 75 | 82 to 100 | 113 to 129 | 129 to 141 |
| 50 L | 50 to 56 | 67 to 83 | 91 to 111 | 125 to 143 | — |
| 60 L | 60 to 67 | 80 to 100 | 109 to 133 | — | — |
| 70 L | 70 to 78 | 93 to 117 | 127 to 156 | — | — |
| 80 L | 80 to 89 | 107 to 133 | — | — | — |
A dash means no rider of that level between 35 and 140 kg fits the board. The same arithmetic as the calculator, run backwards, with no shape adjustment.
Volume from length, width and thickness
Length runs nose to tail along the stringer, not around the curve. Width is the widest point, which sits behind the middle on almost every board. Thickness is the thickest point, usually just in front of centre. All three are quoted in feet and inches by everyone who sells boards, and in millimetres by everyone who makes them.
Length on its own says little. The 68 sizes of 5'10" shortboards, grovelers, fish, twin fins and step-ups in the catalogue run from 26.2 to 36.1 litres for eight boards in ten.
Multiply the three and you have the box the board was cut from: a 6'0" × 20" × 2 ½" is a 59 litre box. The finished board is a little over half of it, and how much over depends on how full the rails are, how much the deck domes and how the foam runs into the nose and tail. We measured it on every size in the catalogue whose maker publishes all four figures.
| Board type | Share of the box | Middle half |
|---|---|---|
| Step-up52 sizes | 51.1% | 50.8% to 51.5% |
| Shortboard379 sizes | 53.4% | 52.5% to 54.2% |
| Twin fin62 sizes | 55.2% | 54.3% to 56.0% |
| Groveler370 sizes | 56.1% | 54.7% to 56.9% |
| Midlength70 sizes | 56.3% | 54.1% to 57.5% |
| Longboard29 sizes | 58.8% | 56.9% to 59.2% |
Published volume divided by length × width × thickness, for 971 sizes of 105 models from five makers (Pyzel, Channel Islands, Firewire, Native, DHD), as each publishes them. Read from SurfPoint's model catalogue on 15 October 2026. The bar is the middle half of each type, the notch its median. Types with fewer than 20 sizes are left out.
Knowing the type, the box lands within 5 per cent of the published figure for nine boards in ten. For that 6'0" × 20" × 2 ½" shortboard the middle half says 31 to 32 litres. Five per cent of a 30 litre board is a litre and a half either way, and the typical step from one size of a model to the next is 1.6 litres. So the box is a fair check on a seller's figure and a poor way to choose between two sizes. The volume printed on a board comes from the shaper's own file, which is why every listing here states it and marks it when it was read off a photograph.
Why the same litres feel different
Volume tells you how much the board floats. It does not tell you where the float sits, and that is what you feel. Thirty litres spread through a wide, flat fish sits under your chest and pushes you into waves early. The same thirty litres in a narrow step-up is carried under the rails, so it paddles slower and holds a line when the face steepens.
That is why the shape adjustment exists, and why it is small: moving from a shortboard to a fish is worth about 6 per cent. If you are switching between board types, change one thing at a time. Keep the litres and change the outline, or keep the outline and change the litres.
Two more things move the number and neither is on the form. Cold water means a wetsuit, and a 4/3 adds buoyancy you did not ask for. And how often you surf matters more than how well: someone who paddles four times a week carries less foam comfortably than someone equally skilled who surfs on holiday.
Four ways people get volume wrong
- Buying the board you want to ride.
- The most common one by a distance. A board two litres under what you need costs you the waves you would have caught, and you improve by catching waves.
- Reading a shortboard table as a beginner table.
- The ratios many sites publish were written for shortboards. Applied to someone learning, they produce a number for a board that person cannot paddle, let alone stand on.
- Trusting a volume nobody measured.
- A litre figure written on a board in marker is usually right. One worked out from length, width and thickness is an estimate, good to about five per cent. One a seller remembers is a guess.
- Forgetting where you are surfing.
- Bali in the dry season is not your home beach break. A board that works in soft two-foot waves is a handful at head-high Uluwatu, and a step-up you brought for that is a paddling exercise on a small day at Batu Bolong.
Common questions
- How do I work out what volume surfboard I need?
- Multiply your weight in kilograms by the litres per kilogram for how you surf: 0.9 to 1.0 for a beginner, 0.45 to 0.55 for an intermediate and 0.35 to 0.4 for an advanced surfer. A 75 kg intermediate lands at 33.8 to 41.3 litres. Then adjust for the shape: about 6 per cent more for a fish and 18 per cent more for a midlength.
- What volume surfboard for a 70 kg surfer?
- It depends on how you surf. At 70 kg a beginner wants 63 to 70 litres, an improver 42 to 52.5, an intermediate 31.5 to 38.5 and an advanced surfer 24.5 to 28. 70 kg is 154 lb. Pick the level that describes what you do in the water today, and the shape then moves the figure a few per cent.
- What volume surfboard for a 180 lb surfer?
- 180 lb is 82 kg. At that weight a beginner wants 73.8 to 82 litres, an improver 49.2 to 61.5, an intermediate 36.9 to 45.1 and an advanced surfer 28.7 to 32.8. The calculator on this page takes pounds too: pick lb beside your weight.
- How much volume does a beginner need?
- About your own body weight in litres. The beginner row here is 0.9 to 1.0 litres per kilogram, so a 75 kg beginner wants 67.5 to 75 litres, which is a soft top or a funboard. Tables written for shortboards give a beginner roughly half that, and a board that small will not float someone who is learning to stand up.
- How do I convert length, width and thickness to litres?
- Multiply the three in centimetres and divide by 1,000 for the box the board was cut from. A finished board fills a little over half of it: across 971 sizes published by five brands, the middle half came to 53.2 to 56.3 per cent. A 6'0" × 20" × 2 ½" is a 59 litre box and a shortboard of about 32 litres. The calculator on this page does the sum by board type.
- What is the Guild factor?
- The ratio this calculator uses: litres of board per kilogram of rider, named after Whitney Guild. The Guild tables were written for shortboards, so their lowest row is a novice on a shortboard. Someone learning on a soft top needs 0.9 to 1.0 litres per kilogram, which is why the beginner row here is so much higher than on calculators built on those tables.