The Snow Water Equivalent (SWE) calculator computes of the volume of liquid water contained in rain or snow pack defined by area, depth and snow type or rain.
INSTRUCTIONS: Choose units and enter the following:
Liquid Water Volume (V): The volume is returned in gallons. However, this can be automatically converted into other volume units (e.g. liters or cubic yards) via the pull-down menu.
The Snow Water Equivalent calculator computes the amount of water in snow. See YouTube video instructions. Different classifications of snow and ice have different water densities. These are listed in the table. This calculator computes the rough volume of the snow by multiplying the area (a) times the depth of snow (d). Then, the volume of water content can be computed by multiplying the volume of snow by the density of water in the snow based on the type of snow. This gives you the mass of the liquid water, which is converted easily into volume units such as gallons. Density of snow can range anywhere from 5% when ambient air temperature is 14 F, and can range up to 20% if the temperature is 32 F. The snow density will increase after the snowfall due to gravitational settling, packing, wind effects, melting and refreezing. The table contains a generally accepted range of density (kg/m3) for different types of snow. The equation will use a median value for the ranges in the density value column.
|Type of snow or ice||(kg/m3)|
|Fresh New snow||50-70|
|Damp new snow||100-200|
|Wind packed snow||350-400|
The area covered by snow may be difficult to estimate. Here are some simple calculators to help you compute the area. To compute the size of your snow covered area, you must first identify the shape of the area.
The areas entered can be small for things such as patios and roofs, and they can be large like a county.