Crane Wind Speed Calculator
Cladding panels, formwork, air handling units and roof sheets catch far more wind than a mobile crane load chart allows for. Work out the reduced maximum wind speed for your load, using the EN 13000 reference the charts are built on. Built by a CPCS A61 Appointed Person.
Crane wind speed calculator
The load plus the hook block and lifting accessories
From the crane's load chart for this configuration (often 9 m/s, some charts higher)
Wind area of the load
Length × height of the biggest side the wind could hit, e.g. a 6 m × 3 m panel = 18 m²
Drag coefficient (cw)
Use the load supplier's figure if they give one
For mobile cranes with EN 13000 load charts. Wind speeds are 3-second gusts at the top of the boom, which are higher than forecast speeds at ground level. The crane's own load chart book and wind diagrams govern. Need a crane lift plan?
How the calculation works
Mobile crane load charts to EN 13000 are calculated for a load with a wind area of 1.2 m² per tonne, including its drag coefficient. A load that catches more wind than that puts more force on the crane at the same wind speed, so the wind speed has to come down:
vmax = vchart × √(1.2 × hoisted load in t ÷ wind area in m²)
Wind area = largest face area × drag coefficient (cw). The 1.2 is the fixed reference in the standard, not a drag coefficient, and does not change. When the wind area is 1.2 m²/t or less, the chart wind speed applies.
| Shape | Typical cw |
|---|---|
| Flat panel, plate or box | 1.1 to 2.0 |
| Cylinder (tank, pipe, column) | 0.6 to 1.0 |
| Wind turbine rotor blade | about 1.6 |
| Sphere | 0.3 to 0.4 |
Worked example
A 6 m × 3 m cladding panel weighing 4.0 t with its lifting accessories, on a crane whose chart allows 9.0 m/s.
- Wind area: 18 m² × 2.0 = 36 m², or 9.0 m² per tonne, far above 1.2
- Maximum wind speed: 9.0 × √(1.2 × 4.0 ÷ 36) = 3.3 m/s, about 7 mph
So this panel must not be lifted in gusts above about 3.3 m/s, little more than a light breeze, even though the chart says 9.0 m/s.
Illustrative figures only.
Questions
What wind speed is on a crane load chart?
Mobile crane load charts built to EN 13000 give a maximum wind speed, often 9 m/s (20 mph) though some charts allow more. It is a 3-second gust speed at the highest point of the crane, and it only applies to loads whose wind area is no more than 1.2 m² per tonne.
Why do large panels need a lower wind speed?
Wind force rises with the area it hits and with the square of the wind speed. A light load with a big face, like a cladding panel, formwork or a roof sheet bundle, can catch several times the wind the chart allows for, so the wind speed has to come down to keep the force on the crane within what the chart was calculated for.
How do I work out the wind area of a load?
Multiply the largest face that could turn into the wind (length × height) by the drag coefficient for its shape: about 1.1 to 2.0 for a flat panel or box, 0.6 to 1.0 for a cylinder. Load suppliers sometimes give the figure, and their figure should be used when they do.
Is the forecast wind speed the same as the wind at the boom head?
No. Wind is stronger with height and gusts are stronger than the average speed, so the gust at the top of a long boom is often well above a ground-level forecast. Use the crane’s anemometer and gust forecasts for the working height.
More on wind limits for every type of lifting equipment: crane wind speed limits explained.
Sources: BS EN 13000, Cranes — Mobile cranes (1.2 m²/t load wind area reference); Liebherr-Werk Ehingen, Influence of wind on crane operation (training document), section 5.2.
Lifting panels or other large-area loads?
RMT crane lift plans set the wind limit for the actual load, not just the chart figure, alongside the duty, outrigger loads and exclusion zone, written by a CPCS A61 Appointed Person.