Safe Ice Thickness | When Is Ice Safe?
When is ice safe? There is no for-certain absolute answer. Really, ice should never be considered safe. Though there are some safety guidelines to follow for safe ice thickness (listed below).
Safe ice thickness for ice fishing. It’s probably the most common reason for searching for answers in this regard. Whether it’s that, or any other reason, don’t risk your life without knowing the following ice safety guidelines, and the ice thickness chart below.
I’ve sourced data from the Minnesota Department of Natural Resources – I figured that those in MN certainly ought to have good information about this! (“Land of 10,000 Lakes”). This data similarly reflects guidelines from various fishing organizations who publish their recommendations as well.
Ice Thickness Safety
You can’t judge the strength of ice just by its appearance, age, thickness, temperature, or whether or not the ice is covered with snow.
Ice strength is based on ALL these factors — plus the depth of water under the ice, size of the water body, water chemistry and currents, the distribution of the load on the ice, and local climatic conditions.
New Ice vs Old Ice
New ice is usually stronger than old ice. Four inches of clear, newly‑formed ice may be a safe ice thickness to support one person on foot, while a foot or more of old, partially‑thawed ice may not.
Ice Thickness Uniformity
Ice seldom freezes uniformly. It may be a foot thick in one location and only an inch or two just a few feet away.
Ice Over Flowing Water
Ice formed over flowing water and currents is often dangerous. This is especially true near streams, bridges and culverts. Also, the ice on outside river bends is usually weaker due to the undermining effects of the faster current.
Snow Over Ice
The insulating effect of snow slows down the freezing process. The extra weight also reduces how much weight the ice sheet can support.
Ice Near Shore versus Farther Out
Ice near shore can be weaker than ice that is farther out.
Booming and cracking ice isn’t necessarily dangerous. It only means that the ice is expanding and contracting as the temperature changes.
Schools of fish in a given location can also adversely affect the relative safety of ice. The movement of fish can bring warm water up from the bottom of the lake. In the past, this has opened holes in the ice causing snowmobiles and cars to break through.
Safe Ice Thickness | Guidelines
For New, Clear Ice Only (and listed caveats)
Double the thickness guidelines when on white ice or “snow ice”, which is only about half as strong as new clear ice.
4″ Okay for Ice Fishing or activities on foot
5″ Ice Thickness for Snowmobile or ATV
8″ – 12″ Thick Ice for Car or small Pickup
12″ – 15″ Ice Thickness for Medium Truck
How To Check Ice Thickness
You might use an ice chisel (a metal rod with a sharp flat blade at one end) to repeatedly stab into the ice to create a hole. Measure with tape measure. Hook the bottom edge of ice before taking measurement.
An auger. Hand, electric, or gas powered. Drill and measure.
Another way is to use a cordless drill with a Long 5/8 inch Wood Auger Bit (wide enough for your tape measure). It won’t take long to drill through the ice to check the depth. Just use a small tape measure to check for safe ice thickness.
White Ice vs Clear Ice
White ice, sometimes called “snow ice,” is only about one-half as strong as new clear ice so the above thicknesses should be doubled.
Ice Thickness Can Vary Widely
Ice is seldom the same thickness over a single body of water. It can be two feet thick in one place and one inch thick a few yards away due to currents, springs, rotting vegetation or school of rough fish.
Vehicle Spacing On Ice
Vehicles weighing about one ton such as cars, pickups or SUVs should be parked at least 50 feet apart and moved every two hours to prevent sinking. It’s not a bad idea to make a hole next to the car. If water starts to overflow the top of the hole, the ice is sinking and it’s time to move the vehicle!
Never Go Out Alone
Use the Buddy System. Have a length of rope. If you go through the ice while you’re alone, well, that’s bad on you.
The Most Popular Ice Cleats
Crampons Ice Cleats
(view on amzn)
Here’s an article that I wrote about my own personal favorite ice cleats:
[ Read: Best Ice Cleats for Shoes & Boots ]
Continue reading: Wind Chill Frostbite Chart
Saving Lake Ice in an Ice House for Ice Box use during Summer
When I used to ice fish for salmon in the High Rockies, I made a pair of short ice picks, one for each hand, and had them fastned by a loop to each wrist. That way if I did go through the ice, I had a pick right there for each hand, and I could pull myself out. Simple as a sharpened 1/4″ spike in a chunk of broom handle with a paracord loop. Never had to use them, but still would not go out on ice without them.
That is a GREAT IDEA. Thanks for the tip.
(I found this set of ice picks on amzn)
Personally I don’t even like going out on that 1/4 inch of ice on my driveway, all alone over a Lake/Stream/River….. No Thanks.
AND no way in heck I’m going out on Navajo Lake when it freezes, at more than 400 foot deep in places it takes about 25 seconds for the body to shut down when submersed in freezing water.
But thanks for the Article Ken, good info as usual.
But you could cut the ice in blocks and pull it up, maybe retrieve some of the artifacts left by previous boaters…
How safe is it? How fast can you drive a snowmobile or 4 wheeler across it?
I grew up in the Adirondack Mtns. 1 time I went across the river in town and I probably shouldn’t have. I had a 110 Honda 3 wheeler. I started to break through. I stepped on it and made it across. I didn’t go back home that way.
There are too many stories about people falling through, losing a car or a shack. 1 family went out (4 kids Mom and Dad) and fell through. Only the dad and 1 son came back. The next year the dad and son didn’t come back.
No thank you.
Another thing to watch for if you decide to go out onto ice in a reservoir, and that is falling water level. Here in the West, reservoirs draw down water for domestic use all the time. I once saw a small inlet covered in ice, but on the main part of the reservoir the ice appeared to be lower. I quickly realized that the inlet ice was hung up above the water level several feet. That could have been really bad, go through the ice and fall a couple of feet to the water below, you’d never get out! These days the closest I want to get to dealing with ice is for the cool chest, or maybe in a tumbler of “organic solvent” for the holidays.
As a teenager i saw a large chunk of ice on on of Michigan’s great lakes break off, ice fisherman would fish close to the edge and open water. The Coast Guard chopperpick about 5 people and gear off the ice flow which was about 30 foot across. Never will forget the look on the people’s faces floating away on the ice flow, wave action broke the chunk off.
I’ve travelled way out to a rented spear fishing shanty in an old station wagon with the top cut off, Lake St. Clair-Michigan again, if we went in water due to an open pocket or weak ice, the theory was you could get out of the vehicle, only did it once, which was enough due to the “excitement factor” (fear factor) and cold doing 40-50 miles per hour.
There is an old study by the Navy, I recall correctly, measuring harmonic wave action of thick ice due to vehicles travelling on it. Two frogmen (can i still say frogMEN, or should i say underwater-breathing assisted biped humanoids?, I’m so confused…🤤), in a car purposely went through the ice for research on what happens, reading what happens stopped me from ever going on the ice except by foot. ice harmonics are very bad thing.
There are many precautions to take when out on the ice.
#1 Wear a life jacket.( They snicker at me all the time) but screw them.
#2 Ice forms from the shore outward. As you start out use a spud bar every 20ft. to make a hole and check the thickness.
#3 Carry a boat seat cushion with 25-30 ft. of rope attached that you can
throw to any knuckle head that goes for a swim.
#4 Never walk shoulder to shoulder with your pals.20 ft. apart is about right. One person thru the ice is enough.
#5 Carry an emergency whistle on a lanyard around your neck.If it’s windy
yelling for help is not much good. Three blasts on the whistle should get some attention.
#5 If you go out on an ATV over inflate the tires to 8-10 lbs. It will keep you afloat a few minutes. Emphasis on “a few”.
#6 When in doubt stay in the truck with coffee and Blackberry Brandy!
Some good ideas but I would put no faith in the one about tires.
Compared to normal or even modestly under inflated tires, over inflated tires will have significantly no more buoyancy at or near the water’s surface. The buoyancy is determined by the volume of the tire (how much water it displaces) and the weigh it is trying to float. Over inflated tires aren’t significantly bigger as the cord structure in the tire casing constrains it’s size. Nylon cords might stretch a tiny amount but nothing significant in regards to tire volume and kevlar cord tires pretty much stretch not at all. Under inflated tires may actually be a tiny bit safer on marginal ice as they will distribute the load over a slightly larger foot print reducing load concentration a very small amount on the ice. Depending on ice conditions and temperatures, under inflated tires could actually have a little bit more traction.
I”m not going out there on the ice at all. Nope. No thank you.
Only ice i see is bobbing around in my tea,,,,
Just sayin is all.
Went through the ice beaver trapping years ago. Temperature was in the teens, made it about 100 yards and pants froze up. Had to remove them and keep moving to finally make it to my trapping partners’ jeep. That was a long cold ride home. Ice was a good 7″ thick on most of the lake. I found a spot that day that wasn’t.
When you leave to go ice fishing in the morning and wifey tells to be home by 5pm. sharp for supper just say “yes dear”.
Then stop off for a couple brews and straggle in around 8pm.
She will be glad you are alive and not mad anymore.
Well maybe.Probably not.
Safer to just do as we are told.
When I was young I would sometimes go through a small swampy area when going to a friends house. Walking across the frozen swampy area was nice as it was quicker. The water wasn’t deep (6″ to 12″) but had several feet of black thick muck below that. Foot went through a few times over the years and realized one thing (yeah, it took me a while-thick headed and all) that places with vegetation sticking through the ice (such as cattails) the ice was thinner and/or weaker in those locations.
Just something I noticed.
Thanks for the article Ken. We all need the reminder on occasion that discretion is the better part of valor. Some 36 years ago, I ran across a snow bridge while patrolling in my district before season opened up for general public. It was a calculated risk and I lived to tell the tale. I did not think much of this decision until a ranger coworker was killed doing a late season patrol near the end of my career with the NPS. He had more years of back country travel experience than I had so lesson learned: it can happen to any of us.
Try not to travel alone but, if you do, leave a trip itinerary behind. Just like using a life jacket, the dark humor folks like to say it makes body recovery easier. Those spike tip dowels mentioned by Minerjim are the best tools by those who fall through the thin ice.
i have seen where people in Alaska will carry 8 ft poles held horizontally when crossing ice. the idea is if you fall through, the pole will catch the sides and you can pull yourself out.
we don’t have that problem in my area. it might boil in the summer but it never freezes : )
just get your tinder and fuel together before you try and start the fire otherwise it may go out before you get back from foraging for fuel.
you have to tend and feed a fire to get it started well, and in wet or snow conditions it takes constant attention until it gets going good with a hot bed of coals.
if you can get a good solid firebed of coals going, your good as gold.
been there- done that. and had to start all over. i got snowed in at a spot in Utah one fall in my youth, it was a hard learning experience, but one well learned.
good advice for newbie’s, but practice makes perfect.
you learn by doing. but i wouldn’t go that rout. get your stuff together first so that you have it on hand and don’t have to go looking around for it later. you may only have one chance at it. you are going to have to gather it eventually, right? and to build it on top of the snow without clearing it off first is just asinine, is a recipe for disaster.
it’s easy for people to walk out into their backyards and make a youtube video, “take 3”. but try it in the middle of nowhere when your life depends on it and you are half frozen. it doesn’t always work out like in the video’s.
a twig bundle is not going to warm you or last more than a few minuets, you have to be ready with fuel to feed it. and you have to get a real fire going to warm yourself up. the bigger the better.
if i get cold enough i’ll set the dang woods on fire : )
– Elsewhere in the comments, (I think it was under the ferro rod or mag block and ferro rod combo discussion) I gave some details about a boat sinking about ten feet offshore. I mentioned I did have a highway flare, but when I needed it, it was under about 3-4 feet of water. The ferro rod and mag block combo came through for me, that said, no, I didn’t build a nice cooking fire. Dead pine needles, a handful, and several good strips of birchbark. Here in west Texas, a crushed-up tumbleweed will burn like you soaked it in gasoline. Know what you need, before you need it.
– Papa S.
– And before you say something, yes, we get ice here too.
All good points about building an emergency fire after going through the ice. Gathering a bunch of wood quickly as possible. Light it with matches, lighter, Ferro rod? Yeah, if that’s all you have.
But anyone going out on the ice where they could go through would be smart to carry ice picks to get out of the water, and be carrying one or more waterproof highway flares for that emergency fire.(CaliRefugee brought this up sometime back).
This is also why when traveling on ice cover lakes and streams the old Sourdoughs never travelled alone. If one went thru the ice, the other could get him out and start a fire. Just food for thought.
You walked across ice thinking you would be safe, fell through, had to ditch your pack to get out, packs gone, extra clothes gone, ALL your supplies, gone, how are you supposed to start a fire? Your soaked, its 10 degrees or less, 3’ of snow on the ground, nothing really dry anywhere and you are turning into a big stinky blue pop sickle, how exactly does this end well in reality?
Growing up next to a pond in Connecticut, invariably, every winter at least once, I would fall through the ice.
I never gave it a second thought. I would just pull myself out, go home and change into dry clothes.
On several occasions, I witnessed other people fall through, immediately panic and start thrashing around wildly in the water, not even thinking about pulling themselves out.
Once, there were a group of teen-age girls, about my age, skating and then when the ice gave way, they fell through. They immediately panicked and started screaming and thrashing about in the water, not even thinking about how to get out. I was sitting on the bank watching all this and I thought it was the most ridiculous sight.
I started yelling at them, “Stand up. Stand up.” (They were at a shallow part of the pond, only about 3 ft. deep.)
They finally started to stand, all sobbing and shaking. If it was a deeper part of the pond, that would have been it for them had there not been anyone around to help them.
That’s a good example how ‘panic’ can completely override one’s sensibility – think-ability? All they had to do (for starters) was to stand up.
Reminds me of another “ice story”.
Same Connecticut pond.
The local kids had a story passed down from the older kids, about a sunken boat somewhere out in the pond, called “The Mickey Mouse.” Of course, we all thought it was just a “legend’, and didn’t take it seriously.
Well, anybody who is familiar with winter ice on a body of water, knows that every freeze is different, depending on the current weather conditions. This one year, this one freeze had the ice crystal clear, and when I was on the ice, I could clearly see all the way to the bottom. Never happened before, or since.
I walked around, viewing the bottom. All dirty, weedy. And then it happened. Looking down I clearly saw the bow of a large rowboat. As a figure head on the bow’s peak was a figure of Mickey Mouse, brightly painted, in blue shorts and yellow t-shirt. He was looking up, directly at me, with both arms raised and pointing right at me.
An amazing sight. It was very early in the morning and nobody else was round. I then continued walking around on the ice, seeing what I could see. Everything else was pretty dull, so I eventually went back to see “Mickey”.
But, I could not find him again.
Later, I told the other kids what I had seen, but nobody believed me. (“Seeing is Believing.”)
From then on, whenever I hear of another “legend”, I always believe that somewhere, at some time, it was based on fact.
In Alaska they used to make a road across Big lake in the winter. It cut off a lot of miles from one end to the other. Everybody used it but when the ice became rotten, idiots used to have races to see if they could drive across without sinking. It helped to eliminate a lot of idiots up there.
Old man, myself and daughter, (when we were young and dumb) built a fire on Frozen over Long lake. The fire melted some of the top ice and a mosquito hatch happened!
Yes Minerjim, That was me that talked of starting a fire with a highway flare. I also made my own spikes using sections of wooden broom handle, sheet metal screws and some epoxy. When the epoxy set the screws into the handle, I cut off the head of the screw and filed into a sharp point much like track spikes.
I never fell through ice in the classic sense but I have swamped or broached my canoe while out hunting ducks in late fall/early winter. Several times, a highway flare and a brush pile have warmed me up afterwards. My fine motor skills go out the window when I am cold and shivering so I choose the flare over the ferro rod and other primitive methods.
A final note on staying warmer out in the cold: I travel with thermos full of tea or coffee when out in the cold. (2 – pint thermos: one for hot drink, the other filled with hot water for soup later in the day)
Hope you put cord or leather loops off the ends of the handles on those. Pull them out, put one dangling off each wrist before crossing an icy river or going on an icy lake. That way they will be there when you need em. Safe travels!
Good point! We used to put dummy ropes on our home made ice picks. We tied the picks with enough cord to run through the arms of our coats to dangle at the wrist. We could then leave them in the coats for extended periods. When we were kids our folks wouldn’t let us out of the house with out seeing that we had them! We lived by a large bay that had safe spots and dangerous spots and they could vary from year to year. It’s hard to keep kids off ice! We also had to have at least 2 in a group and be spread out. I still have commercial ice picks on hand as well as a throw bag when walking or hiking near water.
A commercial fisherman working a northern Canada lake told me he added a lodge pole pine tree about thirty feet long chained parallel to front and rear bumpers to prevent going through the ice. These tress in the area grow about five to six inches in diameter for thirty or forty feet. He said he broke through the ice with either the front or rear tires many times right to the frame but never lost his vehicle again. Just put down a anchor in the ice and hand winched his way to thicker ice. The truck looked goofy for sure lumbering around on the lake ice but effectively solved a problem.