Ice Thickness Safety Calculator

Check if ice is safe for your planned activity. Based on Minnesota DNR and standard ice safety guidelines.

Measure at the thinnest point you've found

Safe Activities at Current Conditions

  • Walking / Ice Fishing on Foot

    Min 4" clear ice

  • Snowmobile

    Min 8" clear ice

  • ATV / UTV

    Min 10" clear ice

  • Light Truck (under 2 tons)

    Min 12" clear ice

  • Heavy Truck (2+ tons)

    Min 20" clear ice
Ice Growth Estimator
How fast will ice grow tonight? Uses Stefan's law — growth slows as ice thickens.

0 = open water / new freeze

~0.4"
Estimated growth per day
Frequently Asked Questions

A minimum of 4 inches of clear/black ice is needed to safely walk on and ice fish. 6 inches provides a comfortable margin. Always check ice thickness in multiple locations using an ice chisel or auger — thickness can vary greatly across a body of water, especially near inlets, outlets, and currents.

Clear (black) ice forms from still water freezing from the top down. It is the strongest type — maximum structural integrity. White or snow ice forms when snow absorbs water and freezes. It is approximately 50% as strong as clear ice. You need roughly double the white ice thickness for equivalent safety.

Light trucks (under 2 tons) need a minimum of 12 inches of clear ice, with 15 inches for a comfortable margin. Heavy trucks (2+ tons) need 20 inches minimum and 24 inches for comfort. Always check current ice conditions, look for pressure cracks, and know your truck's weight. Never drive alone on ice.

New ice formation depends on air temperature, existing ice thickness, and water movement. At 10°F air temperature on thin ice, roughly 1 inch per day can form. Ice growth slows as it gets thicker (thicker ice insulates the water below). The calculator uses a simplified version of Stefan's law for estimates.