How to Create Fire With a Magnifying Glass

Co-authored by wikiHow Staff

Last Updated: March 9, 2023 References Tested

Creating fire with a magnifying glass is a fun grade-school science experiment. It can also be used in emergency survival situations to kindle a fire without matches or a lighter. You’ll need to collect flammable tinder, and then use the magnifying glass to concentrate the sun’s heat onto the tinder, which will soon spark a fire. As always, be careful with fire, and be sure to make the fire far from any trees, grass, or structures that could catch fire.

Method 1

Method 1 of 3:

Selecting a Tinder

1
Use a few sheets of newspaper as tinder if you have some nearby. Newspaper burns easily, and makes a great fire starter. Choose 2-3 sheets of newspaper, and tear them each into 3-4 pieces. Then crumple each of the newspaper pieces into a ball. At this point, you’re ready to light one of the newspaper balls on fire.
- Or, if you prefer, you could place all of the newspaper balls together and use them to light a large piece of wood on fire.
- If you don’t have newspaper, you can use paper towels as tinder instead. They’ll burn in practically the same way.^{[1]
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2
Choose a piece of char cloth for tinder for a very flammable option. Char cloth is made from fabric that has already been charred. Consequently, it ignites at low temperatures compared to other types of tinder. This makes char cloth an ideal type of tinder to use when starting a fire with a magnifying glass.^{[2]
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Research source} You can use char cloth as a tinder, or pair it with another tinder (e.g., newspaper or pine needles) to ensure that the second tinder catches fire.
- If you have a “bug out” bag or a survival kit, add a few pieces of char cloth so that you won’t be without it in a survival situation.
- You can purchase char cloth at a local hardware store. You could also make your own char cloth using a metal tin, a heat source, and white fabric.
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3
Collect coarse, dry, natural tinder if you’re building a fire in the forest. If you’re building an impromptu fire in a rural or secluded area, you can use leaves, grass, or pine needles to start a fire. Bark can also burn well. Find a tree with loose, fibrous bark, and tear 2 or 3 handfuls off. Before starting your fire, shred the leaves or bark with your hands so that the tinder will catch fire more easily.^{[3]
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- Make sure that natural substances are dry before you attempt to light them on fire. Wet leaves or pine needles will smolder and smoke, but never actually burn.

Method 2

Method 2 of 3:

Igniting the Tinder

1
Choose a safe location to light a fire. Make a fire with your magnifying glass in a location where the fire cannot burn anything else but tinder. Suitable places include a cement sidewalk, an area of dirt with no vegetation surrounding it, or a bricked in fire hole.^{[4]
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- If you are in the forest don’t have a clear area nearby, you can use the side of your foot to sweep leaves and pine needles off of a patch of soil, and then light the fire on the dirt.
2
Hold the magnifying glass between the sun and the tinder. You’ll notice that a small, bright dot appears on the newspaper. Tilt the magnifying glass back and forth as needed to change the dot’s size. In order to create enough heat to start a flame, the circle must be as small as possible.^{[5]
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- Aim to focus the circle until it’s only about ¹⁄₄ inch (0.64 cm) across.
3
Focus the dot in one place for 20-30 seconds. Hold the magnifying glass still until the tinder begins smoking. Lighting a fire with a magnifying glass takes much more time than using a lighter or a match. Keep the circle of concentrated sunlight as still as possible in order to build up heat on the tinder. If you move the circle around on the tinder, the heat will not start a fire.
- If you’re creating a fire on a day without strong, direct sunlight, it may take more than 5 minutes for the tinder to catch on fire.
4
Put the fire out as soon as it’s served its purpose. If you’re simply experimenting with the power of the magnifying lens, you can extinguish the fire as soon as the tinder has started to flame. Or, if you’re building a fire in a survival setting, extinguish the fire once you’ve finished cooking your meal or heating your campsite. To extinguish the fire, use a shovel to place 4-5 shovelfuls of dirt on the fire. Then douse it with water from a hose or bucket.
- Once the fire is out, use your shovel to turn over any smoldering coals and douse them again with water. Make sure that the fire is fully extinguished.

Method 3

Method 3 of 3:

Experimenting with Different Types of Lenses

1
Create a fire with a lightweight, flat magnifying lens for a portable option. A flat magnifying lens is square and roughly 2 inches (5.1 cm) on each side. While flat page magnifiers don’t have as much magnification power as a magnifying glass, they still have enough power and surface area to channel the sun’s heat and catch tinder on fire.^{[6]
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- You can find small magnifying lenses at a local hardware store, or at a pharmacy or grocery store.
- You can also start a fire by using a page-sized flat magnifying lens. Note that one side of a flat magnifier is ridged and the other side is smooth. It will work a little better if you hold it so that the smooth side faces the tinder.
2
Use a lens from eyeglasses to start a fire if you have one handy. Glasses are a great survival tool, which you may already be wearing. If you have a strong prescription—and especially if the prescription corrects for far-sighted vision—the lenses will be shaped in a way that can concentrate the sun’s heat, just like a magnifying glass.^{[7]
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- Eyeglasses aren’t as powerful at focusing the sun’s rays as a magnifying glass, since glasses are only convex one 1 side, while the magnifying glass is convex on both sides.
- Compensate for this by placing 1 drop of clear water on the inside surface of the eyeglasses. This will give the lens 2 convex surfaces, and make it channel more heat onto your tinder.
3
Focus the circle of heat from your lens until it’s as small as possible. Different types of lenses will produce different sizes and shapes of heat circles. So, focus as best you can to make the focal point small. Bring the lens as close to the paper as necessary, and angle it towards the sun.^{[8]
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- Be aware that, if you’re using a flat page magnifier, the concentrated image will be rectangular and not round.
4
Do not look directly at the hot circle if using a large focusing device. Large lenses—for example, a flat page magnifier—will make an extremely bright area, much more so then a standard round 2–3 inches (5.1–7.6 cm) round glass. Do not stare at the point of light, or you may seriously damage your eyes.
- Consider wearing sunglasses if you’re using a large focusing device. The glasses will protect your eyes from potential damage.

Community Q&A

Question

What is the fastest way to burn something with a magnifying glass?

Community Answer

The fastest way to burn something with a magnifying glass is to use newspaper. The easiest part to start a fire on a newspaper is an area on which there is a lot of black ink, like in the black and white photos, etc.
Question

How hot does the temperature have to be to burn the paper?

Community Answer

Paper burns at 451 degrees Fahrenheit, or 233 degrees Celsius.
Question

Will this work if it is cold but there is sun?

Community Answer

Yes. It may just take longer.

Warnings

Make sure you do not burn yourself when using the magnifying glass. Never direct the heat from the magnifying glass onto your skin.

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Do not look directly at the sun when trying to locate it in the sky. Also, never look at the sun through your magnifying glass.

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Do not hold the tinder while you’re lighting it on fire with a magnifying glass. If it catches flame more quickly than you anticipate, you could burn your hand.

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Have water nearby in case of an emergency.

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