A paper parachute takes about 10 minutes to build and requires just a sheet of paper, string, tape, and a small weight. The key to one that actually floats slowly instead of tumbling is getting three things right: canopy shape, string length, and a small vent hole at the top. Here’s how to build one that works well, along with the science behind each step.
What You Need
- Paper: A standard sheet of printer paper, tissue paper, or a lightweight paper grocery bag. Tissue paper works best because it’s lighter, but regular paper is fine for a first build.
- String or thread: Lightweight string, kite string, or sewing thread. You’ll need four pieces.
- Tape: Clear tape or masking tape for reinforcing attachment points.
- Scissors
- A small weight: A paper clip, binder clip, small toy figure, or washer to act as the payload.
Cut the Canopy
Cut your paper into a circle roughly 10 to 14 inches across. The simplest method: fold your sheet of paper in half, then in half again, so you have a quarter-pie shape. Measure the radius you want from the folded corner, mark an arc, and cut along it. When you unfold, you’ll have a circle.
Circular canopies produce the longest descent times compared to square, triangular, or star shapes. Testing at the California State Science Fair confirmed that circles generate the most drag and the best stability during flight. A square works too if you’d rather skip the folding and cutting, but expect a slightly faster drop.
Add a Vent Hole
This step is optional but makes a noticeable difference. Cut a small hole in the very center of your canopy. For a 12-inch parachute, that means a hole roughly half an inch to just over an inch across (about 5 to 10 percent of the total diameter).
The vent hole lets trapped air escape through the top instead of swirling around inside the canopy. Without it, air pressure builds unevenly, causing the parachute to rock side to side or even flip over. The hole reduces that turbulence and keeps the descent smooth and straight. A vented circular parachute outperforms every other shape and configuration in both flight time and stability.
Reinforce the String Attachment Points
Paper tears easily where the strings connect, so this step prevents your parachute from ripping apart on its first flight. Mark four evenly spaced points around the edge of the circle, like the corners of a square. Place a small piece of tape over each mark on both sides of the paper, creating a reinforced patch. Then use a hole punch or the tip of your scissors to poke a small hole through each taped spot.
Attach the Strings
Cut four equal lengths of string. The ideal length is roughly twice the diameter of your canopy. For a 12-inch parachute, cut each string to about 24 inches. This ratio gives the canopy enough room to open fully and catch air while keeping the payload stable below it. Strings that are too short pull the edges down and prevent the canopy from inflating. Strings that are too long let the payload swing wildly.
Thread one string through each reinforced hole and tie a knot. Add a small piece of tape over each knot for extra security. Gather all four loose ends together, make sure they’re even, and tie them in a single knot. Attach your weight to this bottom knot by tying it on or clipping it with a paper clip.
Why It Works
A parachute slows things down by creating drag, the same force you feel when you hold your hand out of a car window. As the parachute falls, air pushes up against the underside of the canopy. The larger the surface area catching air, the more drag force is generated and the slower the descent. This is why a bigger canopy falls more slowly than a smaller one made from the same material.
The drag force increases with the square of the falling speed, meaning even small changes in speed produce big changes in resistance. As soon as your parachute begins to drop, air resistance climbs rapidly until it balances out the pull of gravity. At that point, the parachute reaches a steady falling speed instead of accelerating.
Test and Adjust
Drop your parachute from the highest safe point you can find: a staircase landing, a balcony, or just standing on a chair. Hold it by the canopy so it hangs naturally, then release it. Watch how it falls. A good parachute opens quickly, drifts down steadily, and doesn’t spin or flip.
If the parachute flips upside down or oscillates wildly, your vent hole may be too small or missing entirely. Try widening it slightly. If it falls too fast, the canopy might be too small relative to the weight, so try a lighter payload or a larger sheet of paper. If it drifts sideways, check that your strings are all the same length and evenly spaced around the edge.
Variations to Try
Once your basic design works, experimenting is where it gets interesting. Try building three parachutes of different sizes using the same weight, and time their drops from the same height. You’ll see a clear relationship between canopy area and descent time. You can also test different materials: tissue paper, coffee filters, newspaper, or plastic wrap each have different weights and air permeability, which changes how they perform.
For a more advanced build, try cutting a hexagon or octagon canopy with six or eight strings instead of four. More attachment points distribute the load more evenly and help the canopy hold a rounder shape in the air. You can also experiment with vent hole sizes. A hole at 5 percent of the canopy diameter improves stability with minimal drag loss, while a 10 percent hole makes the descent even smoother but slightly faster.