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Calcimator

Ice Thickness Safety Calculator

Check whether ice is thick enough for walking, snowmobiling, or driving. Adjusts for ice type, water current, and air temperature to give an effective thickness and safety rating.

Inputs

inches
°F

Results

Effective Thickness

6"

Safe for Walking1
Safe for Snowmobile1
Safe for Car0
Safe for Truck0
Safety Rating4
How to Use This Calculator
  1. Enter Measured Ice Thickness (inches) — drill or chisel test holes in multiple spots, since thickness varies across a frozen lake.
  2. Select Ice Type: clear/black ice is strongest, white/opaque ice is about half as strong, and snow ice (frozen slush) is weaker than clear ice too.
  3. Enter Air Temperature (°F) — temperatures above 32°F reduce the ice's effective load-bearing thickness.
  4. Select Water Current level (no current, slow, or moderate) — moving water thins ice from below and creates weak spots.
  5. Review Effective Thickness and the safe-use indicators for walking, snowmobiling, cars, and trucks.
  6. Never assume safe conditions — always test multiple locations and avoid ice with water pooling on top.

How the result changes with Measured Ice Thickness

Measured Ice ThicknessEffective Thickness
4.84.8"
1717"
3131"
4343"

What each input means

Measured Ice Thickness
Thickness of the ice measured by drilling in multiple spots. Always test in several locations — thickness varies.
Ice Type
Type of ice affects load-bearing strength.
Air Temperature
Current air temperature in Fahrenheit. Temperatures above 32°F weaken the ice surface.
Water Current
Moving water thins ice from below.

What each result means

Effective Thickness
Ice thickness adjusted for type, current, and temperature. This is the strength-equivalent in clear ice inches.
Safe for Walking
1 = Yes (requires 4" effective clear ice), 0 = No.
Safe for Snowmobile
1 = Yes (requires 6" effective clear ice), 0 = No.
Safe for Car
1 = Yes (requires 10" effective clear ice), 0 = No.
Safe for Truck
1 = Yes (requires 14" effective clear ice), 0 = No.
Safety Rating
1 = Extremely dangerous, 2 = Dangerous, 3 = Walking only, 4 = Moderate activities, 5 = Vehicle-safe.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Measured Ice Thickness = 6, Ice Type = 0, Air Temperature = 20, Water Current = 0 = 4 input(s) provided
  2. Calculate Effective Thickness
    Effective Thickness
    6 = 6
  3. Calculate Safe for Walking
    Safe for Walking
    1 = 1
  4. Calculate Safe for Snowmobile
    Safe for Snowmobile
    1 = 1

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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