Ice Thickness Chart: How Thick Is Safe Ice?

Short answer: the minimum for new, clear ice is 4 inches to go out on foot. Snowmobiles and ATVs need 5 to 7 inches. Cars and small pickups need 8 to 12 inches in the New York DEC chart. Medium trucks need 12 to 15 inches. These numbers only apply to new, clear, solid ice. Double them for white ice.

No ice is ever 100% safe. Check it yourself.

Ice thickness is a guide, not a guarantee. The Minnesota DNR says it does not measure ice thickness on Minnesota lakes and that your safety is your responsibility. Ice can be two feet thick in one place and one inch thick a few yards away. Drill a hole, measure, and keep measuring as you go.

Ice thickness chart (new, clear ice only)

Two state agencies publish charts. They agree on foot travel at 4 inches. They split the snowmobile, ATV and vehicle rows differently, so both are shown.

The Minnesota DNR says its numbers are based on average equipment weight and solid, clear ice. You are responsible for knowing the weight of your vehicle, your gear and your group. When the two charts differ, use the thicker number.

The chart only works for clear ice

The chart is built on new, clear, solid ice. Everything else is weaker.

• White ice. When snow melts and refreezes on top of lake ice, it makes white ice. It is only about half as strong as new, clear ice. Double the thickness on the chart.
• Slush. New York DEC says slush ice is about 50 percent weaker.
• Ice over running water. New York DEC says clear ice over running water is about 20 percent weaker. Its chart is built for non-running water.

Many things besides thickness change ice strength. The Minnesota DNR lists air temperature, wind, snow, streams, narrow areas or bottlenecks, sun, shade, fish communities and plant decay.

Where ice is weakest

Stay well back from these spots, even when the rest of the lake is locked up.

• Moving water. Ice formed over flowing water and currents is often dangerous. That is most true near streams, bridges and culverts.
• Rivers and creek mouths. New York DEC says to be alert where streams enter and exit lakes and ponds. The Minnesota DNR notes gas holes are more likely at stream inlets.
• Springs. The Minnesota DNR names springs and currents as factors in how safe ice is.
• Pressure ridges and cracks. The Minnesota DNR says pressure ridges are always dangerous. Cold snaps make ice contract and crack. Lake water seeps up into the cracks and freezes.
• Bubblers. New York DEC warns that bubblers near docks can make thin, unsafe ice some distance away.
• Shoreline. New York DEC also says to be alert near shore.

Tracks are not proof. New York DEC says snowmobile tracks or footprints on the ice are not evidence of safe ice.

How to check ice thickness

Use a tool that makes a clean hole, then read the thickness with a tape measure.

1. Spud (ice chisel). A heavy metal rod with a flat blade. Stab through the ice, then measure. The Minnesota DNR calls it especially important in early and late season, when the ice is thinner than mid-winter.
2. Auger. Hand, electric or gas. Drill a hole and measure.
3. Cordless drill. The Minnesota DNR says a long 5/8-inch wood auger bit will drill through 8 inches of ice in under 30 seconds.
4. Tape measure. Put it in the hole and hook the bottom edge of the ice. Pull it tight and read the inches at the surface of the ice.

Check often, not just once at the shore. The Minnesota DNR warns that on 4 to 6 inches of ice you will likely find spots under 4 inches on the same lake. Do not judge thickness by how easily a chisel breaks through. It happens fast and it is easy to overestimate.

What to carry

The Minnesota DNR ice safety gear guidance:

• Foam life jacket or flotation suit. The DNR calls it possibly the number one item that keeps you alive if you fall through.
• Ice picks. The second most important item. They give you grip to pull yourself out.
• Ice cleats. They prevent slips and falls on slick, new ice.
• Whistle. An inexpensive way to call for help if others are on the lake.
• Phone in a waterproof case. The DNR also suggests a personal locator beacon for solo trips.
• Rope. To help someone else, call 911, stay back and throw them one end instead of walking up to the hole.
• Spud or auger and a tape measure.

New York DEC says to use the buddy system. The Minnesota DNR also says it is best to go on the ice with a buddy.

If you break through

The Minnesota DNR says to learn these steps before you need them. First, try not to panic.

1. Keep your clothes on. Heavy clothes can trap air that gives warmth and flotation.
2. Turn back the way you came. That is probably the strongest ice.
3. Grab the ice. Ice picks, nails or sharpened screwdrivers help you grip.
4. Kick and pull. Work your body onto the ice. You may need to lift partway onto your elbows to drain water from your clothes.
5. Lie flat and roll away. Roll away from the hole to keep your weight spread out.
6. Get warm right away. Find shelter and rewarm. In serious cases of hypothermia, get medical help.

Parking and vehicles

The Minnesota DNR says frozen lakes are not parking lots. Park cars, pickups and SUVs at least 50 feet apart and move them every two hours to prevent sinking. Loads parked longer than two hours need thicker ice than the chart. Make a hole next to the vehicle. If water starts to overflow the top of the hole, the ice is sinking. Move the vehicle.

Bottom line

Wait for at least 4 inches of new, clear ice before you walk out. Add inches for every step up in weight. Double the number for white ice. Skip moving water, inlets, springs and pressure ridges. Carry picks, wear a float suit, and measure as you go.

No ice is ever 100% safe. Check it yourself.

FAQ

How thick does ice need to be to walk on?

At least 4 inches of new, clear ice. Both the Minnesota DNR and New York DEC use that number. Under 4 inches, the Minnesota DNR says stay off.

How thick does ice need to be for a snowmobile or ATV?

New York DEC lists 5 inches. The Minnesota DNR lists 5 to 7 inches for a snowmobile or small ATV and 7 to 8 inches for a side-by-side ATV.

Is white ice as strong as clear ice?

No. White ice is only about half as strong as new, clear ice. Double the thickness on the chart.

How often should I check ice thickness?

Often. The Minnesota DNR says ice is seldom the same thickness across a lake, so measure again as you move, not just at the shore.

Do tracks on the ice mean it is safe?

No. New York DEC says snowmobile tracks or footprints are not evidence of safe ice.