Triangular bandages are one of the most versatile pieces of first aid equipment. A single square of fabric, cut or folded diagonally into a triangle, can serve as a sling, a pressure pad, a wound covering, or a way to secure a splint. Standard versions measure roughly 90 by 90 by 120 centimeters and are made from calico or similar woven cotton, though disposable non-woven versions are common in modern first aid kits.
Arm Slings for Upper Body Injuries
The most recognizable use for a triangular bandage is the arm sling. There are two main types, and each one serves a different purpose depending on the injury and how much elevation the arm needs.
A broad arm sling supports the forearm roughly parallel to the ground. It works well for an injured upper arm, a hurt wrist or forearm, rib fractures, or any situation where the person can still bend their elbow comfortably. The wide base of the triangle cradles the forearm while the two ends tie behind the neck.
A high arm sling (sometimes called an elevation sling) raises the hand and forearm so the fingertips rest near the opposite shoulder. This elevated position helps control bleeding from hand or forearm wounds and reduces swelling after an injury or infection. If someone has a deep cut on their hand that’s actively bleeding, a high sling keeps the wound above heart level while you get them to medical care.
When tying either sling, position the knot to the side of the neck rather than directly over the spine. A knot sitting on bone creates a pressure point that becomes painful quickly. The reef knot is the standard choice because it lies flat against the skin and holds securely without slipping. To tie one, cross the left end over the right and tuck it under, then cross the right over the left and tuck again.
Folding Into Pads and Bandages
A triangular bandage doesn’t have to stay triangular. Folding it in half lengthwise creates what’s called a broad fold bandage, a wide strip useful for wrapping larger areas like the chest or thigh. Folding it in half once more produces a narrow fold bandage, a firmer strip that works well for securing dressings or binding smaller areas like a wrist or ankle.
These folded strips, often called cravat bandages, are the form you’ll use most outside of sling applications. A narrow fold can hold a gauze pad firmly over a wound, wrap around a head injury to keep a dressing in place, or bind a knee to limit movement. Because you’re working with multiple layers of fabric rather than a single sheet, the cravat provides more compression and stability than the open triangle.
Controlling Bleeding
For wounds that are bleeding heavily, a triangular bandage folded into a thick pad can serve as a pressure dressing. You place the pad directly over the wound and tie it tightly enough to maintain steady pressure. This is especially useful when you need both hands free, since a tied bandage applies constant force without someone standing there pressing on it.
Combining a high arm sling with direct pressure gives you two mechanisms working together: the elevation reduces blood flow to the area while the bandage compresses the wound itself. For hand and forearm injuries, this combination can significantly slow bleeding while waiting for professional help.
Securing Splints for Fractures
When someone breaks a bone and you need to immobilize the limb, triangular bandages folded into cravats are the traditional tool for holding a splint in place. For an upper arm fracture, padded boards or sticks are positioned along the arm and secured at multiple points with cravat ties. Forearm and wrist fractures use the same approach, with the splint material running along both sides of the injured area.
Leg fractures require more bandages. Military field manuals describe using five or more triangular bandages to secure a single leg splint, placed at intervals along the limb to keep everything stable. The key is padding the splint material first and tying the cravats firmly but not so tight that circulation gets cut off. You can check this by pressing on a toenail or fingernail beyond the bandage. If color returns within two seconds after you release, blood flow is adequate.
Even without a rigid splint, triangular bandages can immobilize a fractured leg by binding it to the uninjured leg, using the healthy limb as a natural splint. Cravats tied at the ankles, knees, and thighs hold both legs together and prevent the broken bone from shifting during transport.
Improvising in an Emergency
You won’t always have a proper triangular bandage on hand. The good news is that almost any large piece of fabric works as a substitute. You need a square roughly 5 feet (1.5 meters) across, folded or cut diagonally to form a triangle. A bedsheet, tablecloth, or large towel will do. For a child, a smaller piece works fine.
If you don’t have anything large enough to cut, you can improvise a sling from a belt, necktie, rope, or even a buttoned shirt. Pin the hem of a jacket to its chest to cradle an arm. These solutions aren’t as comfortable or adjustable as a proper triangular bandage, but they accomplish the core goal: keeping the injured limb still and supported until professional care is available.
Why First Aid Kits Include Them
Most commercial first aid kits contain at least two triangular bandages, and there’s a reason. A single bandage can only do one job at a time, and many injuries need more than one. A broken arm, for example, might require one bandage as a sling and another folded into a cravat to bind the upper arm against the chest for extra stability. A leg fracture could easily use four or five.
They’re also lightweight, pack flat, and don’t expire the way adhesive bandages or antiseptic wipes do. A calico triangular bandage stored in a sealed pouch stays usable for years. If you’re building or restocking a first aid kit for your home, car, or hiking pack, carrying three or four of them covers most realistic scenarios you might encounter.