Steel Beam Span Chart
The lightest wide flange (W) steel beam for spans from 8 to 40 feet and uniform loads from 250 to 3,000 pounds per foot. Find your span and load, read off the size, and check it in the free beam designer before you build.
Each size is the lightest AISC W shape in ASTM A992 steel (50 ksi) that passes three checks under AISC 360-16: LRFD bending and shear strength, live load deflection under span/360 and total load deflection under span/240. Click a size for its dimensions, strength and full load table.
How to use the chart
- Find the span: the distance between the beam's supports, in feet.
- Work out the load per foot of beam. Multiply the floor or roof load in pounds per square foot by the width of floor the beam holds up (half the joist span on each side). Dead plus live load on a house floor is about 55 psf (15 dead and 40 live).
- Round up to the next load column and read off the size.
For example, a 20 ft beam under floor joists that span 12 ft on each side holds up 12 ft of floor (6 ft from each side). At 55 psf that's 660 lb/ft, so use the 750 lb/ft column: a W12×16. If it must fit in 10 inches of depth, the W10 chart gives a W10×22.
Steel beam span chart
| Span | 250 lb/ft | 500 lb/ft | 750 lb/ft | 1,000 lb/ft | 1,500 lb/ft | 2,000 lb/ft | 3,000 lb/ft |
|---|---|---|---|---|---|---|---|
| 8 ft | W6×8.5 | W6×8.5 | W6×8.5 | W6×8.5 | W6×8.5 | W8×10 | W10×12 |
| 10 ft | W6×8.5 | W6×8.5 | W6×8.5 | W6×9 | W8×10 | W10×12 | W12×14 |
| 12 ft | W6×8.5 | W6×8.5 | W8×10 | W8×10 | W10×12 | W12×14 | W10×19 |
| 14 ft | W6×8.5 | W8×10 | W10×12 | W10×12 | W12×14 | W12×16 | W12×22 |
| 16 ft | W8×10 | W10×12 | W10×12 | W12×14 | W12×16 | W12×22 | W14×26 |
| 18 ft | W8×10 | W10×12 | W12×14 | W12×16 | W12×22 | W14×22 | W16×31 |
| 20 ft | W10×12 | W12×14 | W12×16 | W12×22 | W14×22 | W16×26 | W18×35 |
| 22 ft | W10×12 | W12×14 | W12×22 | W14×22 | W16×26 | W16×31 | W18×40 |
| 24 ft | W12×14 | W12×19 | W14×22 | W14×26 | W16×31 | W18×35 | W21×44 |
| 26 ft | W12×14 | W12×22 | W14×26 | W16×26 | W18×35 | W18×40 | W21×48 |
| 28 ft | W12×16 | W14×22 | W16×26 | W16×31 | W18×40 | W21×44 | W21×55 |
| 30 ft | W12×19 | W14×26 | W16×31 | W18×35 | W21×44 | W21×48 | W21×62 |
| 32 ft | W12×22 | W16×26 | W18×35 | W18×40 | W21×44 | W21×55 | W24×68 |
| 34 ft | W14×22 | W16×31 | W18×35 | W21×44 | W21×50 | W24×55 | W24×76 |
| 36 ft | W14×22 | W18×35 | W18×40 | W21×44 | W24×55 | W24×62 | W24×84 |
| 38 ft | W14×26 | W18×35 | W21×44 | W21×48 | W24×55 | W24×68 | W27×84 |
| 40 ft | W16×26 | W18×40 | W21×44 | W21×55 | W24×68 | W24×76 | W30×90 |
- Loads are service (unfactored) loads, not counting the beam's own weight, which the checks add. 70% of the load is taken as live load.
- The beam is simply supported and its top (compression) flange is braced along its length, for example by joists or decking fastened to it. A beam braced only at its ends is weaker; the beam designer checks it.
- The chart doesn't cover point loads, such as a post bearing on the beam, or bearing at the supports.
W8 span chart
The lightest W8 for each span and load, for when the beam has to fit in 8 inches of depth.
| Span | 250 lb/ft | 500 lb/ft | 750 lb/ft | 1,000 lb/ft | 1,500 lb/ft | 2,000 lb/ft | 3,000 lb/ft |
|---|---|---|---|---|---|---|---|
| 8 ft | W8×10 | W8×10 | W8×10 | W8×10 | W8×10 | W8×10 | W8×13 |
| 10 ft | W8×10 | W8×10 | W8×10 | W8×10 | W8×10 | W8×13 | W8×18 |
| 12 ft | W8×10 | W8×10 | W8×10 | W8×10 | W8×15 | W8×18 | W8×28 |
| 14 ft | W8×10 | W8×10 | W8×13 | W8×15 | W8×21 | W8×28 | W8×40 |
| 16 ft | W8×10 | W8×13 | W8×18 | W8×21 | W8×31 | W8×40 | W8×58 |
| 18 ft | W8×10 | W8×15 | W8×21 | W8×28 | W8×40 | W8×58 | – |
| 20 ft | W8×13 | W8×21 | W8×28 | W8×40 | W8×58 | W8×67 | – |
| 22 ft | W8×15 | W8×28 | W8×40 | W8×48 | W8×67 | – | – |
| 24 ft | W8×18 | W8×35 | W8×48 | W8×58 | – | – | – |
| 26 ft | W8×21 | W8×48 | W8×58 | – | – | – | – |
| 28 ft | W8×28 | W8×58 | – | – | – | – | – |
| 30 ft | W8×35 | W8×67 | – | – | – | – | – |
| 32 ft | W8×48 | – | – | – | – | – | – |
| 34 ft | W8×48 | – | – | – | – | – | – |
| 36 ft | W8×58 | – | – | – | – | – | – |
| 38 ft | W8×67 | – | – | – | – | – | – |
W10 span chart
The lightest W10 for each span and load, for when the beam has to fit in 10 inches of depth.
| Span | 250 lb/ft | 500 lb/ft | 750 lb/ft | 1,000 lb/ft | 1,500 lb/ft | 2,000 lb/ft | 3,000 lb/ft |
|---|---|---|---|---|---|---|---|
| 8 ft | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 |
| 10 ft | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 | W10×15 |
| 12 ft | W10×12 | W10×12 | W10×12 | W10×12 | W10×12 | W10×15 | W10×19 |
| 14 ft | W10×12 | W10×12 | W10×12 | W10×12 | W10×15 | W10×19 | W10×26 |
| 16 ft | W10×12 | W10×12 | W10×12 | W10×15 | W10×22 | W10×26 | W10×39 |
| 18 ft | W10×12 | W10×12 | W10×17 | W10×19 | W10×26 | W10×39 | W10×54 |
| 20 ft | W10×12 | W10×15 | W10×22 | W10×26 | W10×39 | W10×49 | W10×68 |
| 22 ft | W10×12 | W10×19 | W10×26 | W10×39 | W10×49 | W10×68 | W10×88 |
| 24 ft | W10×15 | W10×22 | W10×30 | W10×45 | W10×60 | W10×77 | W10×112 |
| 26 ft | W10×17 | W10×26 | W10×45 | W10×54 | W10×77 | W10×100 | – |
| 28 ft | W10×19 | W10×39 | W10×54 | W10×68 | W10×100 | – | – |
| 30 ft | W10×22 | W10×45 | W10×60 | W10×77 | W10×112 | – | – |
| 32 ft | W10×26 | W10×54 | W10×77 | W10×100 | – | – | – |
| 34 ft | W10×39 | W10×68 | W10×88 | W10×112 | – | – | – |
| 36 ft | W10×45 | W10×77 | W10×100 | – | – | – | – |
| 38 ft | W10×49 | W10×88 | – | – | – | – | – |
| 40 ft | W10×54 | W10×100 | – | – | – | – | – |
W12 span chart
The lightest W12 for each span and load, for when the beam has to fit in 12 inches of depth.
| Span | 250 lb/ft | 500 lb/ft | 750 lb/ft | 1,000 lb/ft | 1,500 lb/ft | 2,000 lb/ft | 3,000 lb/ft |
|---|---|---|---|---|---|---|---|
| 8 ft | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 |
| 10 ft | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 |
| 12 ft | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×19 |
| 14 ft | W12×14 | W12×14 | W12×14 | W12×14 | W12×14 | W12×16 | W12×22 |
| 16 ft | W12×14 | W12×14 | W12×14 | W12×14 | W12×16 | W12×22 | W12×30 |
| 18 ft | W12×14 | W12×14 | W12×14 | W12×16 | W12×22 | W12×26 | W12×40 |
| 20 ft | W12×14 | W12×14 | W12×16 | W12×22 | W12×26 | W12×35 | W12×53 |
| 22 ft | W12×14 | W12×14 | W12×22 | W12×26 | W12×35 | W12×45 | W12×65 |
| 24 ft | W12×14 | W12×19 | W12×26 | W12×30 | W12×45 | W12×58 | W12×87 |
| 26 ft | W12×14 | W12×22 | W12×30 | W12×40 | W12×58 | W12×72 | W12×106 |
| 28 ft | W12×16 | W12×26 | W12×35 | W12×50 | W12×72 | W12×87 | W12×136 |
| 30 ft | W12×19 | W12×30 | W12×45 | W12×58 | W12×79 | W12×106 | W12×152 |
| 32 ft | W12×22 | W12×35 | W12×53 | W12×72 | W12×96 | W12×136 | W12×170 |
| 34 ft | W12×26 | W12×45 | W12×65 | W12×79 | W12×120 | W12×152 | W12×210 |
| 36 ft | W12×26 | W12×53 | W12×72 | W12×96 | W12×136 | W12×170 | W12×230 |
| 38 ft | W12×35 | W12×65 | W12×87 | W12×120 | W12×152 | W12×190 | W12×279 |
| 40 ft | W12×35 | W12×72 | W12×106 | W12×136 | W12×190 | W12×230 | W12×305 |
Steel beam span questions
How far can a steel beam span?
As far as you like if it's deep enough, but most building beams have a span of 15 to 24 times their depth. Under a light 500 lb/ft load, a W14×26 spans 30 ft and a W18×40 spans 40 ft; under 2,000 lb/ft the same spans need a W21×48 and a W24×76.
What size steel beam do I need for a 20 ft span?
For a typical house floor load of 500 to 1,000 lb/ft, a W12×14 to W12×22. Shallower beams need more weight: in 8 inches it takes a W8×21 to W8×40.
Why are deeper beams lighter?
Bending strength and stiffness grow with the square and cube of depth, so moving steel away from the middle is the cheapest way to make a beam stronger. That's why the lightest size at long spans is always a deep one. See steel beam sizes to compare shapes.
Can I use this chart instead of an engineer?
It's for picking a starting size. Building departments usually want calculations for the actual loads, supports and connections; the beam designer prints them, and the steel beam design guide walks through them by hand.