How the Cat Grimace Scale Works

The Cat Grimace Scale reduces a difficult question into five small comparisons. Instead of asking whether a cat looks painful, it asks how each part of the face compares with three reference states.

The scoring structure

The scale uses five facial features: ear position, orbital tightening, muzzle tension, whisker position, and head position. Each feature is scored from 0 to 2. A score of 0 means the sign appears absent, 1 means it is moderately present, and 2 means it is markedly present. The five individual scores are added together to give a total from 0 to 10.

This structure matters because it prevents a single dramatic feature from dominating the result. A cat with one markedly changed feature and no other signs scores 2 out of 10, while a cat with all five features moderately changed scores 5. The total and the individual scores together give a more complete description than either alone.

Step by step

1. Choose a clear photo.
2. Observe one facial feature at a time.
3. Compare the feature with the reference illustrations.
4. Review the individual scores.
5. Consider the overall context before acting.

1. Look at one feature at a time

Start with a single area, such as ear position. Ignore the rest of the face for that step. The goal is to describe one feature accurately rather than to reach an overall impression in the first few seconds.

2. Compare with reference illustrations

Match the cat against the three examples for that feature: absent, moderately present, and markedly present. The reference illustrations give each score a visual definition, which is more consistent than trying to remember what mild or marked looks like.

3. Score, then move on

Record a 0, 1, or 2 and move to the next feature. If a feature is hidden by fur, shadow, or camera angle, mark it as not visible rather than forcing a score. The assessment tool handles this step automatically and keeps a running total.

How the total is interpreted

A total close to 0 suggests the face looked relaxed at the moment of observation. A higher total suggests more of the five features appeared tense, narrowed, flattened, or lowered. Published owner-facing guidance for the Feline Grimace Scale uses a total of 4 or higher as a prompt to contact a veterinarian, as described on the official Feline Grimace Scale practice page. That number is a practical threshold, not a medical diagnosis.

The total should always be read with the cat's normal behaviour in mind. A cat that has always held its ears slightly low may score differently from a cat whose ears have only just changed. The most informative use of the scale is repeated observation over time, so that the owner is comparing the cat with itself. Read more in the guide to interpreting Cat Grimace Scale scores.

Taking a useful photo

The scale is designed for clear, front-facing photographs, and photo quality has a large effect on the result. A useful photo shows both ears, both eyes, the muzzle, and the whisker area with reasonable light. A straight-on or slightly side view works better than a photo taken from above, which can make the eyes look narrowed and the head look lowered.

• Use natural, even light that does not cast a hard shadow across the face.
• Keep the face large enough in the frame to see the eyes and muzzle clearly.
• Avoid extreme angles, heavy blur, and strong colour filters.
• Photograph the cat when it is awake and settled, rather than mid-groom or mid-meal.

Why the order matters

Moving through the features in a fixed order reduces two common errors. The first is halo bias, where an owner decides the cat is painful early and then scores every feature high. The second is over-reliance on the most obvious feature, usually the ears, while missing a subtle change in the eyes or muzzle. A checklist keeps attention on each action unit separately.

What affects the result

Stress, fear, sleep, and environment all change facial expression, and none of them is scored by the scale itself. A cat photographed in a carrier may show flattened ears and narrowed eyes because of fear rather than pain. A cat photographed while dozing may look squinted and relaxed at the same time. The scale does not cancel these effects out; it simply records what the face looked like in that image.

Because of these limitations, the result should be treated as one piece of information. If the score is high, contact a veterinarian and describe the observations you made. If the score is low but the cat's behaviour has changed, trust the behaviour and seek advice anyway.

Starting an assessment

The website tool follows the same process described above. It shows your photo beside the reference images, moves through the five features one at a time, allows you to skip features you cannot see, and explains the total at the end. The photo is processed locally in your browser and is not uploaded to a server. Start the assessment.

Sources and further reading

• Feline Grimace Scale official website — felinegrimacescale.com
• Evangelista MC, et al. Facial expressions of pain in cats: the development and validation of a Feline Grimace Scale. Scientific Reports. 2019. DOI 10.1038/s41598-019-55693-8