Dog Food Transition Calculator
Switching a dog to a new food too quickly is one of the most common causes of upset stomachs, loose stools and vomiting. The gut bacteria need time to adjust. This calculator builds a gradual 7-day or 10-day plan, showing exactly how much old and new food to give each day.
Build the transition schedule
Calories per kg are printed on the food bag as ME or metabolisable energy. If the label shows kcal per 100 g, multiply by 10. Typical dry dog food is 3,300 to 4,000 kcal per kg.
Estimated daily energy: 1059 kcal for a healthy adult dog at normal activity.
- Day 175% old / 25% newOld food: 220 g (110 g per meal)New food: 70 g (35 g per meal)
- Day 275% old / 25% newOld food: 220 g (110 g per meal)New food: 70 g (35 g per meal)
- Day 350% old / 50% newOld food: 145 g (73 g per meal)New food: 140 g (70 g per meal)
- Day 450% old / 50% newOld food: 145 g (73 g per meal)New food: 140 g (70 g per meal)
- Day 525% old / 75% newOld food: 74 g (37 g per meal)New food: 210 g (105 g per meal)
- Day 625% old / 75% newOld food: 74 g (37 g per meal)New food: 210 g (105 g per meal)
- Day 70% old / 100% newOld food: 0 gNew food: 280 g (140 g per meal)
How to switch your dog's food
- Mix the old and new food together in the same bowl at each meal.
- Weigh the food with a kitchen scale; cups can vary by 20% or more.
- Keep treats small and the same as usual so you can tell how the new food is going.
- Make sure fresh water is always available.
- If stools soften, go back one step and stay there for 2 to 3 days before moving on.
- Contact your veterinary clinic for vomiting, blood in the stool, refusal to eat, or diarrhoea lasting more than 48 hours.
How the calculation works
The schedule follows the stepped method used in veterinary practice: 75% old and 25% new, then 50/50, then 25% old and 75% new, and finally 100% new. Daily calories are estimated from the resting energy requirement, RER = 70 × (body weight in kg)0.75, multiplied by an adult maintenance factor. Each food's share is then converted to grams from its own calorie density, so total energy stays steady.
Are you a veterinary practice?
The Vet.Portions clinic workspace builds transition plans from a verified catalogue of real foods, covers puppies, seniors, weight change and slower 14 or 21-day plans, and prints a client handout in one click. Start a 7-day free trial.
Frequently asked questions
- How long should it take to switch my dog to a new food?
- Most dogs do well over 7 days: 75% old and 25% new, then 50/50, then 25% old and 75% new, then 100% new food. Dogs with a sensitive stomach, seniors and dogs moving onto a very different diet often do better over 10 days or longer.
- What should I do if my dog gets loose stools during the switch?
- Go back to the previous step that your dog tolerated and stay there for 2 to 3 days before moving forward again. Contact your veterinary clinic if there is vomiting, blood in the stool, lethargy, or diarrhoea lasting more than 48 hours.
- Why are the grams different for the old and new food?
- Foods carry different amounts of energy per kilogram. The calculator splits your dog's daily calories, not just the weight of food, so a richer food is fed in a smaller amount. That keeps the total daily calories steady throughout the switch.
- Can I switch from dry to wet food with this schedule?
- Yes. Enter the calories per kg from each label. Wet food usually has far fewer calories per kg than dry food, so the gram amounts of wet food will be much larger. A 10-day schedule is a good idea for big changes in food type.
- Does my dog always need a gradual transition?
- A gradual change is recommended for almost every food switch. Your veterinarian may advise an immediate change in some medical situations, for example when starting certain prescription diets. Always follow their instructions in that case.