Stop guessing how much to feed your cat. Calculate daily kcal with the vet-standard RER/MER formula, then convert the result into dry food, wet food, mixed feeding, treat budget, and a safe weight-loss plan.
Macronutrient Analysis
Based on cats' natural prey diet composition and NRC minimum nutrient requirements.
Life Stage Curve
For a typical 4.5kg neutered female domestic cat.
Calorie needs peak at 3-4 months during rapid growth, then decline after spay/neuter.
Most adult cats need 180-250 kcal/day, far less than many feeding guides suggest.
Some senior cats need more calories as digestive efficiency declines.
Science
RER = 70 x 4.5^0.75 = 216 kcal/day
RER represents the energy needed to sustain basic biological processes at rest: breathing, circulation, neural function, cellular repair, and organ maintenance. It is the floor, not the feeding target.
MER = 216 x 1.2 = 259 kcal/day
MER accounts for activity, thermoregulation, digestion, growth, reproduction, recovery, and lactation. The life stage factor explains why two cats of the same weight can need very different calories.
Obligate Carnivore Nutrition
5.2g/kg/day minimum
Cats use protein as a primary energy source and cannot down-regulate protein catabolism when dietary protein is low. Adequate animal protein protects lean mass.
1.3g/kg/day minimum
Fat provides energy density, palatability, fat-soluble vitamin absorption, and essential animal fatty acids such as arachidonic acid.
0% minimum requirement
Cats have no dietary carbohydrate requirement. Natural prey is usually 3-5% carbohydrate calories, while many dry foods are far higher.
Sources: NRC (2006), MSD Veterinary Manual, CatInfo.org, and AAFCO nutrient profiles.
Reference Table
Daily calorie targets for neutered indoor adult cats at different weights. Adjust +/-20% for activity and individual variation.
| Weight | RER | Typical Neutered x1.6 | Typical Intact x1.8 | Weight Loss x1.0 |
|---|---|---|---|---|
| 2.0 kg | 118 kcal | 189 kcal | 212 kcal | 118 kcal |
| 2.5 kg | 139 kcal | 222 kcal | 250 kcal | 139 kcal |
| 3.0 kg | 160 kcal | 256 kcal | 288 kcal | 160 kcal |
| 3.5 kg | 179 kcal | 286 kcal | 322 kcal | 179 kcal |
| 4.0 kg | 198 kcal | 317 kcal | 356 kcal | 198 kcal |
| 4.5 kg | 216 kcal | 346 kcal | 389 kcal | 216 kcal |
| 5.0 kg | 234 kcal | 374 kcal | 421 kcal | 234 kcal |
| 5.5 kg | 251 kcal | 402 kcal | 452 kcal | 251 kcal |
| 6.0 kg | 268 kcal | 429 kcal | 482 kcal | 268 kcal |
| 6.5 kg | 285 kcal | 456 kcal | 513 kcal | 285 kcal |
| 7.0 kg | 301 kcal | 482 kcal | 542 kcal | 301 kcal |
| 7.5 kg | 317 kcal | 507 kcal | 571 kcal | 317 kcal |
| 8.0 kg | 333 kcal | 533 kcal | 599 kcal | 333 kcal |
| 8.5 kg | 348 kcal | 557 kcal | 626 kcal | 348 kcal |
| 9.0 kg | 364 kcal | 582 kcal | 655 kcal | 364 kcal |
| 9.5 kg | 379 kcal | 606 kcal | 682 kcal | 379 kcal |
| 10.0 kg | 394 kcal | 630 kcal | 709 kcal | 394 kcal |
Food Labels
The numbers you need are on every bag and can. Use calories by weight, not cup estimates.
GUARANTEED ANALYSIS
Crude Protein ........ 30%
Crude Fat ............ 15%
Moisture ............. 10%
Ash .................. 7%
CALORIE CONTENT: 3,500 kcal/kg = 350 kcal/100g = 385 kcal/cup
Carbs are usually not listed. Estimate them as 100 - protein - fat - fiber - moisture - ash, then compare foods on a dry matter basis.
GUARANTEED ANALYSIS
Crude Protein ........ 9%
Crude Fat ............ 5%
Moisture ............. 78%
Ash .................. 7%
CALORIE CONTENT: 850 kcal/kg = 85 kcal/100g = 133 kcal/can
Carbs are usually not listed. Estimate them as 100 - protein - fat - fiber - moisture - ash, then compare foods on a dry matter basis.
Related Tools
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Calculate daily portions in grams and cups for dry, wet, or mixed diets adjusted for age, weight, and activity.
Compare your cat's weight against breed-specific healthy ranges and get a Body Condition Score interpretation.
Calorie science
The calorie calculator separates resting energy requirement from maintenance energy requirement. That distinction matters because a cat's body weight sets the baseline, while life stage, neuter status, activity, growth, lactation, and weight goals determine the real daily target.
RER is the resting baseline. MER is the practical daily target after the appropriate factor is applied. Macro targets then help evaluate whether the food label supports a cat's obligate-carnivore needs rather than only meeting a calorie number.
RER is the energy needed at rest. Most cats need a multiplier above RER unless the goal is carefully managed weight loss.
Spay and neuter status can lower energy needs and increase appetite, which is why intact and neutered adults should not always share the same calorie target.
Wet and dry foods can look very different on an as-fed label. Dry-matter analysis makes food comparisons more meaningful.
RER and MER are most valuable when they help you decide whether to maintain, reduce, increase, or investigate. The right response depends on whether the cat's body trend matches the calorie target.
Maintenance target
A maintenance result should keep weight and body condition steady over time. Short-term appetite changes should not automatically trigger a new target.
Keep the target stable and compare weight trend over the next two to four weeks.
Weight-loss target
The target should be based on a safe ideal-weight plan, not a severe cut from current intake. Cats need gradual change to reduce health risk.
Convert the calorie target into measured food grams and monitor weekly.
High-demand life stage
Kittens, pregnant queens, lactating cats, and underweight cats can need substantially different factors than a neutered adult.
Recalculate whenever life stage changes instead of reusing an adult maintenance number.
Review maintenance targets against real weight trend and body condition.
Check weekly during weight-loss, gain, pregnancy, or lactation planning.
Re-run the math when switching foods or changing treat routines.
Growth, pregnancy, lactation, adult maintenance, and weight goals use different factors, so the life-stage input should match the cat's current biology.
Use the food calculator next if you need grams, cans, cups, or mixed-feeding portions from the calorie number.
If body weight moves in the wrong direction for two to four weeks, adjust the target carefully instead of making daily reactive changes.
FAQ
Most adult cats need between 150-300 kcal per day, depending on weight, life stage, activity level, and whether they are spayed or neutered. The standard veterinary formula is RER = 70 x body weight in kg^0.75, then MER = RER x the right life-stage multiplier. A typical 4 kg neutered adult using a 1.6x multiplier needs about 317 kcal/day.
RER is the minimum calories needed to sustain life at rest. MER is the real daily need after multiplying RER by a life stage factor for activity, neuter status, growth, pregnancy, lactation, or weight goals.
For weight loss, calculate calories from the cat's ideal weight, not current weight, using a weight-loss multiplier of 1.0. Safe cat weight loss is about 0.5-1% of body weight per week. Never reduce calories by more than 20-25% at once because rapid restriction can trigger hepatic lipidosis.
Find kcal per cup on dry food or kcal per can on wet food, then divide the cat's daily meal calories by that food density. If mixing wet and dry food, allocate a percentage of daily calories to each food type and calculate each portion separately.
Treats should stay under 10% of total daily calories, and those calories should be subtracted from meals. For a cat that needs 250 kcal/day, treats should be limited to about 25 kcal/day.
Neutered cats usually have lower energy needs than intact cats. A typical neutered adult uses a 1.6x MER multiplier, while a typical intact adult uses about 1.8x. Monitoring food intake and body condition is especially important after neutering.
Kittens need much more energy per kg than adult cats. Kittens under 4 months use about 3.0 x RER, while kittens 4-12 months use about 2.0 x RER. They should eat kitten-specific food and transition gradually to measured adult meals as growth slows.