How To Start a Fire With a Magnifying Glass?

Burning a paper with a magnifying glass using under sun light

A magnifying glass isn’t always used just for magnification. One can simply start fire with a magnifying glass because of its unique properties which have long been known. It takes me back to the days of getting in big trouble in childhood for  inadvertently igniting important papers.

Starting a fire with nothing but a lens and the presence of Sun is pretty cool and can amaze your kids. There are also several advantages to having a magnifying glass. For starters, they don’t get used up, like matches or lighters, and they are extremely versatile.

 In the absence of matches or a lighter, it can be used in emergency survival situations to kindle a fire when needed. You don’t have to carry a magnifying glass in your bug-out bag specifically for survival situation, a pair of glasses will work just as well, or, if you have binoculars, you can use one of the lenses. You can add some water on it to enhance the effects.

Using eye glass as a magnifying glass to crate fire in survival situation
photo credit: wikihow

Many campers and people who live in a rural area know that a fire can be useful for cooking food, keeping warm, and providing light. If you have a magnifying glass with you, you can use it as a heat source to start a fire with small pieces of tinder.

Building a Fire With Magnifying Glass

Creating fire using magnifying glass is one of the easiest alternative methods to start fire once you understand it. You can easily make fire by following these instructions step by step. Let’s get down to details.

  • You need a safe location where the fire cannot spread to anything else since you need to perform the activity outdoor. 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 trees surrounding it.
  • Now hold the magnifying glass between your tinder and the sun. As soon as the magnifying glass is under the clear sky and sun focusing on the paper, it gives a bright dot on the paper. You can make the dot size bigger by tilting the lens back and forth. Keep in mind that keeping the dot size as small as possible will create the fire sooner.

  • You need to focus the dot in one place for 20-30 seconds. Hold the magnifying glass still until the tinder begins smoking. Starting 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.

    Remember, if you’re creating a fire on a day without strong, direct sunlight, it may take few more minutes for the tinder to catch on fire. First, you observe some smoke from the focused area. Then the fire comes slowly after smoke appears.
Create Fire With Magnifying Glass and Paper
Create Fire With Magnifying Glass and Paper
  • You have to put the fire out as soon as you don’t need that anymore. 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.

    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 bucket.

Types of Magnifying Glass You Can Use

Since it rules out what can and can’t start a fire, it’s important to know the different types of magnifying glasses you can use. Here are the most common materials that are used as a magnifying glass to start a fire optically:

  1. Glass
  2. Plastic
  3. Ice STEM

A big number of magnifying ‘glasses’ are actually made out of plastic. Plastic is usually cheaper to manufacture, but it usually also harder to break. There are different types of plastics you can use as magnifying lens.

Using plastic as magnifying lens has some drawbacks you need to count including optical impurities, easy to scratch and lower melting point than glass. Despite these drawbacks, a plastic lens is superior in a survival setting just because it is less likely to break.

 A scratched lens is much easier to work with than a broken one. Plastic magnifying glasses are usually lighter weight, which can help when packing a bug out bag since every ounce can matter.

Using plastic magnifying glass to create fire
photo credit: instructables

Types of Tinder You Can Use

As you can’t make fire in everything with the help of a magnifying lens, here are some tinder suggestions with short details that you can use to start fire easily.


Newspaper as tinder is the best ignitable material you can ask for if you have some of them nearby. Newspaper burns easily, and can use as a fire starter.

Take few sheets of newspaper, and tear them each into 2/3 pieces. Then crumple each of the newspaper pieces into a ball. Now you’re ready to light one of the newspaper balls on fire. 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.

Use paper as tinder to create fire
photo credit: wikihow

Char Cloth

Char cloth as a tinder is a very good 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. 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.

Use char cloth as tinder to create fire
photo credit: primalsurvivor

Coarse, Dry, Natural Tinder

Coarse, dry, natural tinder collections can be good flammable option if you want to make fire in a forest. Normally in survival setting in a forest, if you want to build a fire using magnifying glass, you need to collect leaves, grass or pine needles. Loose bark can also be a good option.

Use coarse, dry, natural tinder as tinder to create fire

Science Behind It

Photons are responsible for a magnifying glass to start fire. The photon particles carry or hold clear visible light coming to earth from the sun. These photons transmit energy and lights in the form of heat.

A magnifying glass sets fire by focusing all the photons through the small dot area created by the convex (curved outward) lens. The sunlight hit on the magnifying glass, appropriate focal strength of the photons passes through the lens and creates a small sized dot in the ignitable material like tinder. This generate a huge amount of high heat concentration at the dot area which will do the job and start a fire. As it will take a while to start a fire, you need to wait with patience until the sun catches the fire.

You can read our article How Does a Magnifying Glass Work? to find out more about the working principle of the magnifying glass.


In this part, we will answer some frequently asked questions on making fire with magnifying glass.

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

Yes but as you need a big amount of heat to start a fire, It will take longer time to catch fire if it’s cold outside.

How strong does the sun have to be for this to work in seconds?

A normal hot sunny day will work just fine, but the best time is between 12:00 to 14:00 because the sun will be directly overhead.

Can you make fire using this in your own house?

Yes you can but you need direct sunlight to enter your house. If you have an open window, you can do it easily inside of your house.

Can I do this in the evening?

To do this, you need full sunlight. So, 1 or 2 hours before sunset will do the job. After that it would be very difficult to make fire.

What is the best magnifying glass you can buy online for survival fire starting?

You can use glass and plastic both as a magnifying lens. But, for survival purpose it’s better to use plastic magnifying lens as it’s easy to carry, light weight, and less likely to break.

What is the fastest way to start a fire?

The fastest way to start fire with a magnifying glass is to use newspaper. The easiest part of a newspaper to start a fire is the part with blank ink, you can focus on the blank ink part of a newspaper to start you in the quickest way.

Is it possible to make fire with magnifying glass without sun?

The answer is yes. Since you need energy to focus on a magnifying glass to start fire, you can easily use laser light if there is no sun out there.

Does a magnifying glass works under water?

Since there is very little refraction under water, so a magnifying glass doesn’t work under water.

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