🐾 Feline Maintenance Energy Requirement (MER) Calculator Simulator

Resting Energy Requirement — The Starting Point

RER is the calorie floor a cat burns at rest.

• 70·W^0.75: Formula (kcal/day, W in kg)
• ~200-280: Typical adult (kcal/day at 4kg)
• Metabolic mass: Basis (allometric scaling)
• Baseline only: Use (before multipliers)

Why RER matters

RER anchors every later multiplier in this calculator.

Life-Stage Multiplier — Kitten, Adult, Senior

Growth and aging shift energy needs up or down.

• 2.0-3.0x: Kitten (rapid growth phase)
• 1.2-1.6x: Adult (maintenance range)
• 1.0-1.4x: Senior (lower activity, mass)
• up to 3.0x: Pregnant/lactating (reproductive demand)

Choosing a multiplier

Pick the range matching the cat's current life stage.

Indoor vs Outdoor Activity Multiplier

Outdoor and active cats burn noticeably more calories.

• 1.0-1.2x: Indoor, inactive (low movement)
• 1.2-1.4x: Indoor, average (typical apartment cat)
• 1.4-1.8x: Outdoor access (roaming, hunting)
• up to 2.5x: Working/athletic (very high activity)

Activity adjustment

More movement raises the multiplier used in MER.

Neuter Status Adjustment

Neutered cats generally need slightly fewer calories.

• +10-20%: Intact (higher baseline need)
• -10%: Neutered/spayed (lower metabolic rate)
• 1.2 vs 1.4: Common factor (neutered vs intact adult)
• Obesity risk: Why it matters (post-surgery weight gain)

Adjusting for surgery status

Lower the multiplier slightly after spay or neuter.

Final Daily MER and Food Portion

All factors combine into calories and grams of food.

• RER × mult: Formula (= MER kcal/day)
• ~3.5 kcal/g: Dry food (typical energy density)
• MER ÷ 3.5: Portion (grams per day)
• 2-3 meals: Split (recommended feeding)

Reading the result

Use the portion estimate as a starting feeding guide.

Always confirm portions with a veterinarian for the individual cat.