How to use the pet weight goal date calculator
- Enter the current and goal weights.
- Choose the weekly loss your vet recommends.
- Press Calculate.
Worked example
A dog at 30 kg with a goal of 25 kg, losing 1.5% a week from 18 October 2026.
- Current weight
- 30 kg
- Goal weight
- 25 kg
- Weekly loss
- 1.5% of body weight a week
- Starting date (leave empty for today)
- 2026-10-18
- Weeks
- 13
- To lose
- 5 kg (11 lb)
- Weekly loss
- 1.5% of body weight
An estimate at a steady pace. Weight rarely falls in a straight line, so weigh every two to four weeks and follow your vet's plan.
Example values are illustrative; this result is produced by the same calculator above.
How we calculate it
Sources: AAHA · Pure arithmetic / unit conversion on user inputs (no external constant)
Understanding your result
If your vet has set a goal weight, this calculator estimates when it could be reached at a steady weekly loss. AAHA guidance for dogs is about 1 to 2% of body weight a week, so you choose 1%, 1.5% or 2%.
It uses weeks = ln(goal ÷ current) ÷ ln(1 − weekly loss), rounded up, because each week's loss is a share of a smaller weight. A dog going from 30 kg to 25 kg at 1.5% a week takes 13 weeks, so around 17 January 2027 if it starts on 18 October 2026.
Real weight loss is rarely steady and can plateau. Weigh every two to four weeks and adjust with your vet. Cats must lose weight especially slowly, so ask your vet before using any date.
Common mistakes
- Choosing a faster rate than your vet suggested.
- Treating the date as a deadline.
- Not accounting for treats and extras.
- Using the goal of a different dog or a breed standard.
- Giving up when weight plateaus instead of asking the vet.
Good to know
- Use the Dog Weight Loss Calculator for the calorie target.
- Track progress with the Pet Weight Change Calculator.
- Increase exercise gradually; ask your vet.
When to talk to your vet
- Before starting any diet
- Weight loss faster than about 2% a week
- No change after four weeks
Frequently asked questions
Which weekly loss should I pick?
Your vet sets the plan. AAHA guidance for dogs is about 1–2% of body weight a week; the calculator lets you choose 1%, 1.5% or 2%.
Why is it only an estimate?
Weight loss is rarely perfectly steady, and weight can plateau. Weigh every two to four weeks and adjust with your vet.
Does it work for cats?
Cats must lose weight especially slowly, so ask your vet before using any target date.
Why does the calculation use a logarithm?
Each week's loss is a share of a smaller weight, so the weight falls a little more slowly over time.
What if the date passes and I am not there?
Weight loss plateaus. Ask your vet to review the plan.
Can I enter pounds?
Yes. Switch the unit toggle to imperial and enter both weights in pounds.
Sources
- AAHA (2014) Weight Management Guidelines for Dogs and Cats
- Pure arithmetic / unit conversion on user inputs (no external constant)
Related calculators
- Dog Weight Loss CalculatorPlan a safe weight-loss target: daily calories and how many weeks it should take.
- Pet Weight Change CalculatorTrack a weight change over time: percent change, percent per week and whether the pace is inside 1–2% a week.
- Dog Overweight Percentage CalculatorSee how far above its ideal weight your dog is, in percent and in kilograms.
- Dog Body Condition Score & Ideal Weight CalculatorScore your dog's body condition on the 9-point scale and estimate its ideal weight.
Estimates only. Every pet is different — confirm with your veterinarian. If your pet may have eaten something harmful, contact your vet or an animal poison helpline now.