The Rule of Nines for Burn Injuries

TL;DR: 

The rule of nines is a quick way to estimate burn size and severity so healthcare providers can determine the right treatment. This guide explains how burn depth, location, and total body surface area affect burn treatment options.

• How the rule of nines divides the body into percentages to assess burn size
• Key differences between first-, second-, and third-degree burns
• What each degree of burn looks like and when it becomes serious
• Which burn locations are automatically considered critical
• When to seek urgent care or emergency medical treatment for burns

In evaluating burn severity, two factors matter most. These are the depth of the injury and how much of the body’s surface has effects. Because people differ in size and body shape, the medical community uses percentage-based tools to assess burn size. These estimates are from how much skin typically covers major body areas such as the arms, legs, and torso.

Understanding the Burns Rule of Nines

To standardize burn size estimation, clinicians use the rule of nines. This method divides the body into 11 sections:

• Head
• Right arm
• Left arm
• Chest
• Abdomen
• Upper back
• Lower back
• Right thigh
• Left thigh
• Right leg (below the knee)
• Left leg (below the knee)

Each section equals roughly 9% of total body surface area (TBSA), totaling 99%. The remaining 1% represents the genital area. This allows providers to quickly determine burn extent by adding the areas affected by second- or third-degree burns. For example, the face represents about 4.5%.

Because children have different proportions than adults, professionals use a pediatric rule of nines for kids to improve accuracy. The rule of nines for burns is primarily a rapid field assessment tool. It guides decisions about transfer to specialized burn centers, where more precise measurements are possible.

While burn size is important, the degree of the burn is also essential in determining severity and treatment needs.

Treatment Approaches for Varying Degrees of Burns

Professionals determine burn seriousness by depth and the percentage of the body with injuries. Below, we explain how we classify burns, when home care is appropriate, and when to seek urgent or emergency care.

Burn Degrees

Medical professionals categorize burns by depth. First-degree burns affect only the surface layer while second- and third-degree burns penetrate deeper.

First-Degree Burns

These burns damage the skin’s surface but leave the outer layer intact. This allows the skin to maintain temperature regulation and infection protection. Most first-degree burns are treatable at home.

Second-Degree Burns

Also called partial-thickness burns, these injuries extend into the dermis. Blistering is a hallmark sign as the epidermis separates from the dermis. Once this separation occurs, patients may experience fluid loss, reduced temperature control, and increased infection risk. These burns are usually quite painful because of exposed nerve endings.

Third-Degree Burns

Full-thickness burns affect both the epidermis and dermis. They cause similar complications to second-degree burns but destroy nerve endings, often resulting in reduced sensation. These burns can be difficult to distinguish from deep second-degree burns at first glance.

Recap

Burns are classified by depth:

• • First-degree burns can be treated at home.
• • Second-degree and third-degree burns require professional medical care, and third-degree burns often require emergency treatment.

What Does Each Degree of Burn Look Like?

• First-degree burns: Dry skin, redness, and mild swelling; no blisters.
• Second-degree burns: Blisters, visible layers of skin separation, or shiny red wounds.
• Third-degree burns: Dry, leathery skin that may appear white, black, or charred. Fatty tissue may be visible. These burns may not be painful because they include nerve damage.

Burn Surface Area and What It Means

Burn width is a percentage of body surface area and applies only to burns that are second-degree or worse. Burns covering more than 10% TBSA are generally serious.

Healthcare providers calculate TBSA using the burns rule of nines, which divides the body into:

• Head and neck
• Right arm
• Left arm
• Chest
• Abdomen
• Upper back
• Lower back
• Right thigh
• Left thigh
• Right lower leg
• Left lower leg

The genital area represents the final 1%.

When calling 911 for burn injuries, sharing the estimated TBSA is important. This helps first responders determine whether a burn unit is necessary.

Another quick method: the palm of the hand equals about 1% of TBSA. Burns larger than 3% in adults or 2% in children require immediate evaluation.

Specific Types of Critical Burns

Some burns are considered critical regardless of size if they affect:

• Hands or feet (especially circumferential burns)
• Face
• Genitals

These must be at least second-degree to receive a critical diagnosis.

How Medical Professionals Treat Burns

Treatment principles are similar for all burns, but more severe injuries require additional intervention.

Treating First-Degree Burns

Cool the burn with running water or a cool compress for at least 10 minutes—avoid ice. Clean with mild soap and apply petroleum jelly, aloe vera, or a topical antibiotic (if no allergies). Do not use butter, toothpaste, or oils. Cover with a sterile, nonstick bandage and use OTC pain relievers if needed.

Summary of First-Degree Burn Treatment

• • Use cool running water or a cold compress.
• • Apply petroleum jelly, aloe vera, or antibiotic ointment.
• • Cover with a nonstick bandage.
• • Take OTC pain relievers if needed.

Treating Second-Degree Burns

Follow first-degree burn steps but do not pop blisters. Use a cool compress while waiting for medical care if needed. Anti-inflammatory pain relievers (e.g., ibuprofen) can help with swelling. Elevate the burned area and follow healthcare provider instructions, which may include antibiotic creams like silver sulfadiazine.

Signs of Infection

Seek immediate care if you notice:

• • Pus or drainage
• • Fever
• • Increasing pain
• • Red streaks
• • Swollen lymph nodes

Treating Third-Degree Burns

These burns require emergency care. Patients may need IV fluids, treatment for shock, and, later, skin grafts. Severe burns often require extended hospital stays to monitor for complications. These may include infection, organ failure, pneumonia, or abnormal heart rhythms (in electrical burns).

When to Get Emergency Treatment

Seek urgent or emergency care if:

• Burns cover 3%+ TBSA in adults or 2%+ in children
• Burns occur in infants, elderly individuals, or people with diabetes or weakened immune systems
• Burns affect the face, hands, feet, genitals, or joints
• Burns completely encircle a limb
• Burns result from fire, chemicals, electricity, or inhalation

All third-degree burns and severe second-degree burns require prompt medical attention. Some second-degree burns are treatable at urgent care. Third-degree burns require emergency attention and burn units. 

What Should Not Be Done to Treat Burns

Avoid the following:

• Using household remedies (butter, oil, ice, eggs)
• Removing clothing stuck to the burn
• Popping blisters or removing dead skin
• Using cold water
• Blowing or breathing on the burn
• Allowing someone with airway burns to lie on a pillow
• Allowing food or drink after a severe burn

Insights from TGH Urgent Care powered by Fast Track: Expert Advice on Burns

Professionals classify burns as first-degree, second-degree, or third-degree from depth and extent. First-degree burns are minor while second- and third-degree burns need professional care. Third-degree burns are always an emergency. 

Burns commonly occur from hot liquids, steam, fire, electricity, and chemicals. Prevention, especially in the kitchen, is essential. If you or someone near you experiences a burn, quick action and prompt treatment helps ensure the best outcome. For serious burns, seek immediate treatment at your nearest TGH Urgent Care powered by Fast Track location.

We’re open every day from 8:00 a.m. to 8:00 p.m., with several convenient Greater Tampa Bay, Hillsborough, Pinellas, Pasco, Lee, and Charlotte county locations ready to serve you.

References & Sources

TGH Urgent Care powered by Fast Track uses only high-quality sources, including peer-reviewed studies. This is how we support the facts within our articles.

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• University of Rochester Medical Center. Classification of burns.
• American AED CPR Association. Online first aid class: How to use the rule of nines.
• American Academy of Dermatology Association. How to treat a first-degree, minor burn.
• Cleveland Clinic: healthessentials. Should you put ice on a burn (or not)?
• University of Michigan, Michigan Medicine. Home treatment for second-degree burns.