Quick Answer
A cat weight log is a simple record of your cat’s weight over time — the date, the number, and a quick note. Weighing on the same scale and writing it down turns a slow change that is easy to miss day to day into a clear trend you can see and share at a vet visit. A weight log cannot diagnose anything; it helps you notice changes early and describe them to your veterinarian, who decides what they mean.
Who This Log Is For
- Cat parents who want one steady number to check, instead of guessing whether their cat looks heavier or thinner.
- Anyone living with a kitten, a senior cat, or a cat whose vet has asked them to keep an eye on weight.
- People who like to walk into a vet visit with notes rather than a vague “I think she’s lost a little.”
Why a Cat Weight Log Helps
Weight is one of the few cat care numbers you can measure at home, and it changes slowly enough that your eyes are not a reliable guide. A cat who loses a little each week still looks like the same cat in the morning. Lined up on paper, the same change is obvious.
It matters more in cats than it looks, because cats are small. A 4 kg cat who drops 400 g has lost about 10% of its body weight — proportionally similar to a 70 kg person losing 7 kg. That is why a written trend is worth keeping: the change is easy to wave off on any single day and hard to ignore over a few weeks.
A log is also the kindest thing you can hand your vet. “She was 4.5 kg in March and 4.2 kg this week, eating a little less the last two weeks” is something a vet can work with. Weight tracking also shifts with your cat’s age — see Cat Life Stages Explained for what to start watching at each stage.
What to Record
Keep it short. Five things are plenty, and four of them barely change between entries.
| Item | What to Write Down | Why It Helps |
|---|---|---|
| Date | The day you weighed (the time, too, if you can) | Shows how fast a change is happening, not just that one happened |
| Weight | The number, in kg or lb — pick one and stick with it | A consistent unit keeps the trend readable at a glance |
| Scale used | Pet or baby scale, bathroom scale, or carrier method | Different scales read differently; note it if you switch |
| Conditions | Before or after a meal, and the time of day | A full stomach adds a little; same conditions means a fair comparison |
| Notes | Appetite, energy, or anything that seems different | Adds the context the number alone can’t show |
The notes column is where a log earns its keep. A number on its own says little; a number next to “eating less, sleeping more than usual” is the start of a story your vet can follow.
How to Weigh Your Cat at Home
You do not need special equipment, but the more precise your scale, the smaller the change you can catch.
- A baby or pet scale (most precise). These read in small increments — often 10 to 50 g — which is what you want for a cat. Set it on a hard, flat floor, let it settle to zero, and place your cat on it. If your cat won’t sit still, put a familiar towel, basket, or small box on the scale first, zero it out (tare), then add the cat.
- The bathroom scale method (free and good enough for big changes). Weigh yourself and note the number, then pick up your cat and weigh again. The difference is your cat’s weight. Most bathroom scales round to the nearest 100 to 200 g, so this is better for spotting a real trend than a 30 g wobble.
- The carrier method (easiest for nervous cats). Weigh the empty carrier, then the cat inside it, and subtract — or tare the carrier first on a pet scale. This also gets you a calm reading from a cat who hates being held still.
A few habits make every reading comparable:
- Same scale every time. Two scales rarely agree to the gram.
- Same time of day, ideally before a meal. A recent meal and a long drink can add noticeable weight.
- Write the date down immediately. A reading you can’t place in time can’t show a trend.
Simple Example
Here is what a few months of monthly weigh-ins might look like, with a closer check once something shifts:
| Date | Weight | Conditions | Notes |
|---|---|---|---|
| Mar 1 | 4.5 kg | Morning, before breakfast | Normal, playful |
| Apr 1 | 4.5 kg | Morning, before breakfast | Same as usual |
| May 1 | 4.4 kg | Morning, before breakfast | Eating normally |
| Jun 1 | 4.3 kg | Morning, before breakfast | A little less interested in food |
| Jun 8 | 4.2 kg | Morning, before breakfast | Booked a vet visit, brought these notes |
On any single morning, slipping from 4.5 to 4.4 kg is easy to dismiss. Lined up over a few months, a steady slide is hard to miss — and it is exactly the kind of pattern worth bringing to your vet, even if your cat seems fine otherwise.
How Often to Update It
For most cats, less often than you’d think. Weight moves slowly, and weighing too often mostly records the noise of a full bladder or a recent meal.
| Cat or situation | A common rhythm |
|---|---|
| Kittens | Often weekly while they are growing fast |
| Healthy adults | About once a month is plenty |
| Mature and senior cats | Monthly, or more often if your vet suggests |
| After a food or routine change | A few extra check-ins over the following weeks |
| If your vet is monitoring something | Exactly as often as they ask |
Weighing frequency tracks your cat’s age, too — our life-stage care guides cover what else is worth watching at each stage.
What Not to Do
A weight log is a record, not a referee. A few things to avoid:
- Don’t diagnose from the number. A single reading, or a small wobble between weeks, is not a verdict on your cat’s health. Watch the trend, and leave the interpreting to your vet.
- Don’t start a diet or change food portions on your own. Weight-loss and weight-gain plans for cats come from your veterinarian — restricting food to chase a number can do real harm.
- Don’t switch scales mid-trend. A new scale can shift every reading by a few hundred grams and make a steady weight look like a sudden change.
- Don’t panic over one reading — but don’t ignore a clear, sustained change either. If the trend keeps moving in one direction, that is your cue to call the vet, not to log it again next month.
When to Contact a Veterinarian
A weight log helps you notice change; it does not replace veterinary care. Contact your veterinarian if you notice any of the following:
- Weight loss or gain over a few weeks, even if your cat seems happy and normal otherwise.
- A sustained change of roughly 10% of body weight, or any change that feels sudden.
- Weight dropping while your cat is eating normally or even more than usual.
- Weight loss alongside reduced appetite, vomiting, or drinking and urinating more than before.
- A kitten who is not gaining weight, or is losing it.
- Weight change together with changes in breathing, energy, litter box habits, or mobility.
When something feels off, your written log — what changed, and when — helps your vet far more than trying to remember at the appointment.
Related Guides
- Cat Life Stages Explained: Kitten to Senior — how care, and what to track, shifts with age.
- Senior Cat Care Checklist: What to Observe and Record — weight is one of the most useful things to track for an older cat.
- Life Stage Cat Care guides — stage-by-stage checklists of what to observe and record.
- Cat Care Logs — more simple records that make vet visits easier.