You can tell how bad a burn is by looking at three things: how deep the damage goes, how much skin is affected, and where on the body it’s located. Depth is the most important starting point, and you can assess it yourself by checking the color, texture, and pain level of the burned skin. Here’s how to read those signs and decide what to do next.
The Four Levels of Burn Depth
Burns are classified by how many layers of skin they destroy. Each level looks and feels distinctly different.
Superficial (first-degree): Only the outermost layer of skin is damaged. The burn looks pink to red, feels dry with no blisters, and is moderately painful. A typical sunburn falls into this category. These heal on their own within a week, and scarring is rare.
Superficial partial-thickness (second-degree, shallow): Damage reaches into the second layer of skin. Blisters are the hallmark sign. If a blister breaks open, the skin underneath looks evenly pink or red and turns white briefly when you press on it, then returns to pink. These burns are often quite painful because the nerve endings in that second skin layer are exposed but intact. Healing typically takes two to three weeks, and scarring is usually minimal.
Deep partial-thickness (second-degree, deep): This burn also blisters, which makes it easy to confuse with the shallower version. The key difference is what the skin looks like underneath. Instead of uniform pink, the wound bed looks mottled, with uneven patches of red and white. When you press on it, it turns white slowly and sluggishly returns to color. Pain can vary because some nerve endings are damaged. These burns often take more than three weeks to heal and carry a higher risk of significant scarring. Many require skin grafting.
Full-thickness (third-degree) and deeper: The entire thickness of skin is destroyed. The burned area looks leathery, stiff, and dry. It can be white, brown, or charred black. Pressing on it produces no color change at all because the blood supply in that area is gone. Here’s the counterintuitive part: these burns often feel painless at the site because the nerve endings have been destroyed along with the skin. If a burn looks severe but doesn’t hurt, that’s actually a worse sign, not a better one. Full-thickness burns always need professional treatment and typically require grafting. Fourth-degree burns extend beyond the skin into muscle, tendon, or bone and need specialized surgical care.
The Blanch Test
One of the simplest ways to gauge burn depth at home is the blanch test. Press a finger gently against the burned skin for a moment, then release. If the skin turns white under pressure and quickly returns to pink, blood flow is intact and the burn is likely superficial or shallow partial-thickness. If the skin barely changes color or returns to its resting shade very slowly, the burn is deeper. If pressing produces no color change at all, the full thickness of skin has been destroyed.
This test isn’t perfect, and burns can look different as they evolve over the first 48 to 72 hours. A burn that initially seems shallow can deepen. If you’re unsure, reassess the next day.
How Much Skin Is Burned
Depth tells you how bad the burn is at one spot. The total area of skin involved tells you how dangerous the burn is to your body overall. Medical teams estimate this as a percentage of total body surface area, and you can do a rough version yourself.
For adults, a system called the Rule of Nines breaks the body into sections. The entire head and neck account for 9% of body surface area. Each arm is 9%. The front of the torso is 18%, and the back is another 18%. Each leg is 18%. That adds up to 100% with the remaining 1% for the genitals. A quick shortcut: the palm of your hand (including your fingers) represents roughly 1% of your body surface area, so you can “measure” a burn by estimating how many palm-sized areas it covers.
These numbers shift for children. An infant’s head accounts for about 19% of body surface area, more than double the adult proportion, while their legs make up a smaller percentage. Children also have thinner skin, which means a burn from the same heat source tends to go deeper and cause more damage than it would in an adult.
Location Matters as Much as Size
A burn on your forearm and the same burn on your face are not equally serious. Burns on certain body parts carry extra risks regardless of their size. Burns on the face or neck can swell and threaten your airway. Burns on the hands or feet can damage the tendons and small joints you rely on for movement and grip. Burns over major joints like the elbows or knees can heal with tight scar tissue that limits your range of motion. Burns on the genitals are at high risk for infection and complications.
Any second- or third-degree burn involving the face, hands, feet, genitals, or major joints meets the criteria for referral to a specialized burn center, even if the burn area is small.
Electrical Burns Can Fool You
Most burns are straightforward to assess visually. Electrical burns are the major exception. When electrical current passes through the body, skin resistance determines where the damage shows up. If skin resistance is high, you may see obvious surface burns. But if resistance is low, the current passes through the skin with little visible trace and damages the muscles, nerves, and blood vessels underneath. The surface can look minor while the internal injury is severe. This is why any electrical burn, including lightning injuries, warrants medical evaluation regardless of how the skin looks.
When a Burn Needs Emergency Care
Certain burns require treatment at a specialized burn center. The referral criteria used by hospitals give you a useful framework for knowing when a burn has crossed the line from “treat at home” to “get help now”:
- Third-degree burns larger than 5% of body surface area (roughly five palm-sized patches) in anyone
- Second- or third-degree burns covering more than 10% of body surface area in children under 10 or adults over 50
- Second- or third-degree burns covering more than 20% of body surface area in other age groups
- Burns on the face, hands, feet, genitals, or major joints
- Electrical or chemical burns
- Burns with inhalation injury (from breathing in hot air, steam, or smoke)
- Burns in someone with existing health conditions that could slow healing, such as diabetes or immune disorders
Correct First Aid for a Fresh Burn
Run cool (not cold) water over the burn for at least five minutes. This is the single most evidence-supported first aid step. Do not use ice. Ice constricts blood vessels in the injured tissue and can worsen damage. Do not apply butter, cooking oil, or any greasy ointment. These trap heat in the skin and make the burn deeper than it would otherwise be. After cooling, you can loosely cover the area with a clean, non-stick bandage.
For superficial burns, over-the-counter pain relief and aloe vera or a simple moisturizer are typically enough. For anything with blisters or worse, avoid popping the blisters yourself. Intact blisters act as a natural sterile bandage over the healing skin beneath.
Signs a Burn Is Getting Infected
Any burn that breaks the skin is vulnerable to infection. Watch for increasing pain or tenderness around the wound after the first day or two, especially if the pain was previously stable or improving. A foul smell coming from the wound is a strong warning sign. Spreading redness beyond the edges of the burn suggests cellulitis, a bacterial skin infection that needs antibiotics. Pus or cloudy discharge, fever, or red streaks radiating outward from the wound all signal that infection has set in and needs treatment.
Infection risk rises with burn depth and size. Superficial burns rarely get infected. Deep partial-thickness and full-thickness burns, particularly those that are left open or improperly dressed, are at much higher risk.