A Magnifying Glass For Survival

Magnifying Glass For Survival Fire Starting

A magnifying glass is great for starting fires. As long as the sun is out! It works best with dry tinder like shaved wood, crunched dry leaves, etc. This article update includes 3 current choices (shown below), any of which you might say is the best magnifying glass for fire starting. Actually, one of them may technically be the best because it’s physically bigger than the other two magnifying glass choices as a fire starter (larger diameter equals more area equals more focused energy. But the other two are great too – and fit better in a survival kit.

A Magnifying Glass For A Fire Starter

I do keep a survival magnifying glass in each one of my kits. That’s along with several other methods to start a fire like a lighter, matches, magnesium fire-starter, Vaseline cotton-ball tinder, and more. Check out the fire starter kit list (article link) at the end…

A magnifying glass will start a fire in seconds. That’s under ideal conditions. How long it takes will vary depending on the time of day, angle of the sun, the efficiency / overall size of the magnifying lens, and the tinder being used.

The quality of the glass (which is often plastic) can make a noticeable difference. The ability to focus a tiny bright spot onto the tinder so as to ignite more quickly.

Can a plastic magnifying glass start a fire? Yes, plastic lenses will work. However some of the cheap ones are simply too poorly manufactured to focus a concentrated beam from the sun. Glass or quality acrylic will be better. Check out my choice for wallet size Fresnel lens in the linked article below.

With that said, most every plastic lens I’ve tested as a ‘survival magnifying glass’ worked. However the following three choices for a fire starter magnifying glass are all real glass.

Does the diameter of the magnifying lens make a difference starting a fire? In my experience, not so much of a difference. Although a larger diameter lens will pick up more available light and is quicker and easier to start a fire.

A word of caution (besides the obvious when making fire) is to avoid looking at the concentrated point of light, which could damage your eyes. It can be very bright! Sunglasses?

How Does A Survival Magnifying Glass Work For Fire Starting

What’s the science behind starting a fire with a magnifying glass? Well, it’s about the photons. Photons are the particles that carry visible light from the sun to the earth. They also contain energy in the form of heat.

Through the use of a magnifying glass, the path of these photons are narrowed to a highly localized area (the dot of light resulting from double convex shaped lens). The focal length is the distance from the lens to where the light is focused. This varies depending on the lens manufacture. The resulting concentration of light / heat can reach incredibly high temperatures. If a high enough temperature is reached (somewhere around 450 degrees F), then tinder or kindling will smolder and begin to burn. Be careful where you focus the light!

3 inch Diameter Double Convex Lens (Optical Glass) Fire Starter

One of my recommendations for a best one, is this magnifying glass. It will certainly serve as a fire starter, especially given its 3″ diameter. You get just the lens, so there’s no handle or other bits to take up space in your kit. However you might want to protect it from scratching – depending where you keep it.

Eisco Labs Lens
(view on amzn)

One of the best magnifying glass fire starters

image from Eisco Labs

The lens has an 8 inch focal length. It gathers lots of light. Optically worked, highly polished glass with ground edges for safe handling.

‘RCH’ said, “A great lens for my fire starter kit. It is big enough to be easily focused. I keep it in a cotton draw string bag wrapped in a micro fiber cloth. Perfect for my use.”

2.4 inch Diameter With Case Protector

Slightly smaller, this one has a nice attached case protector. The lens is glass.

Portable Folding Lens

2 inch Diameter Small Folding Pocket Magnifying Glass

The smallest of the three, this glass is convenient given it’s smaller size. Yes, it will still be effective as a fire starter.

2-pack, compact pocket size

‘Matt’ says, “Small, lightweight addition to a camping pack that allows you to start a fire using the power of the sun (*on bright, sunny days). Convenient case keeps them free from scratches. Also would make a great EDC item for people with poor eyesight.”

[ Read: Fire Starter Kit List ]

[ Read: Fresnel Lens For Your Wallet ]


  1. When I was a kid, probably every boy knew how to start fires with a magnifying glass. My brother accidently set the neighbor’s hay field on fire with one…..Dad (not to mention the neighbor) were not impressed.

    While maybe not the best choice for starting fires, many map reading compasses have a built in compass. I have a couple of Silva compasses, both have the magnifier. Have tested to see if they will start a fire successfully. A compass like these kills two birds with one stone.

    1. I wasn’t going to bring that up, but, I do recall participating in that ‘kid sport’.

      1. Maybe when they ban gas stoves, we can use magnifying glasses to cook our insect meals.

        1. Old Alaskan, lmao! You vill eat zee bugs and you vill like it…

          This gives me a new business venture idea. A cricket cooker. ‘Green’ of course…utilizing rays from the sun via high-resolution magnifying glass technology (HRMGT). Gotta get the lawyers working on the trademark. Surely I could sell loads of them to the greenies.

        2. Grasshoppers on a stick … yum. Hey, save me a leg !

          Papa Smurf, I once used one of the SAK Explorer magnifying glass tool, but it took some effort. the lense is so small, getting that point of light requires both hands to steady. Had to hold the tool ‘just so’ and the wind kept blowing the tinder about (vasoline impregnated cotton ball – avoid the synthetic product, they don’t catch fire as quickly).

  2. – I know they are not the style anymore (everybody has to have a multitool in their pocket), but I have one on my SAK which works pretty well. For that matter, I also have a plastic Fresnel lens in my billfold that I know works for the same purpose.

    I once met a young fool who wondered why I would want to start a fire on a day when I had good sunlight; he missed out on hot coffee and fried fish at lunch. PBJ’s for him.

    – Papa S.

  3. Found a couple projector screen tv’s next to the dumpster at my apartment house. Got six mag. Lenses out of each one before the trash man came.

    1. Now that’s a find. Only thing I miss about being in the city, good dumpster diving.

  4. Diameter of the lens is important too. I once had a 150 mm (6”) dia. 10x magnification lens that would ignite dry wood (no tinder) into flame when the diameter of the focus point was around 12mm (1/2”), i,e. not focused to a point.

  5. I’ve even started fires using a clear plastic bottle filled with water.

    1. Also a ziplock bag filled with water with just the right technique can do this too.

  6. I got hold of a fresnel lens that’s about 3′ x 3.5′ from an old TV. They’re getting harder to come by. When I put a stick behind it smoke jumps off instantly. Great thing for someone who lives in the city. You can cook with it, or melt lead with it — or burn your house down with it. Oh, and you can burn ants with it too!

  7. We have what are called “transfer stations” for those who live out of town with no trash pickup. Usually about an acre fenced in, lined with dumpsters. Then they transfer the trash to a truck which takes it to the dump. There is a shelter with a roof to leave donated items. Some people don’t consider you to be an Alaskan until you take something home from the transfer station. I have brought lots home, and donated lots also. I think it adds a sense of community.

    1. Before our local transfer station outlawed pickers, we got the coolest retro chrome and yellow formica kitchen table and chair set. Best dump day ever!

  8. In town, a family owned wild bird seed and birding supply store had a fire in their business early one Sunday morning. Only minimal damage, fortunately. The fire inspector found the fire started when the bright morning sun was refracted and focused by the lovely crystal and glass garden decorations near the east facing front window. Who would have thought that could have been a fire hazard. It’s amazing to think that after traveling 93 million miles, a tiny ray of sunlight still carries so much energy.

  9. we had a yard sale last yerar and my wife had a make-up mirror for sale. the sun reflected off of it and started a fire of some of our yard sale items. that was one way to get rid of our junk.

  10. After cataract surgery I was unable to see the fine print. I got the Oirte lens in the two pack. Works great and can carry in my pocket. Dual purpose! I can recommend this one from personal use and yes it will start a fire.

  11. I remember starting fires (and frying ants) with a magnifying toy from a Cracker Jack box.

  12. Speaking of magnifying glasses, I keep a pair of magnifying reading glasses in my first aid kit. At my age, I use them when removing a splinter or threading a needle.

  13. as i have mentioned before, my magnifying glass on my swiss army knife works great. did not take too long to start with dried leaves.

  14. Find an old cheap binocular at a yard sale or such.
    Unscrew the front lenses.
    You have two very good lenses for the fire kit.
    Had mine for years

  15. Sorry but a magnifying glass is an extremely unreliable way to start a fire, and for me something I would not bother including in my preps (and yes I have started fires as a child with one, and burnt the face off of a star wars action figure). Life is too short to mess around with something that only works when the sun is high in the sky when there are so many other cheap, small, light, and most importantly reliable alternatives. Even in lower latitudes a magnifier only works during the day when the sun is higher in the sky, and in higher latitudes outside of summer months you have an extremely small window if any to start a fire using the sun. For the weight of a heavy glass magnifier you could easily carry a bic lighter a ferro rod, and a couple of cubes of wet fire tinder. With the ferro rod you can start thousands of fires night and day. I keep bic lighters, road flares, and storm matches in all my cars and have a bic lighter, ferro rods and wet fire tinder cubes in all my packs. When I go camping in the winter I include a road flare if you can’t start a fire with a road flare then God must want you to be cold.

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