Colony Population Projector

What's the long-term impact of your TNR efforts on your colony?

The purpose of the Colony Population Projector is to help colony caretakers, rescue organizations, and community advocates understand how a feral or community cat colony is likely to grow over time and what it takes to stabilize or reduce it. Like the Community Cat Calculator, this projection helps you put numbers into the reality of colony management and will provide you with a clearer picture of the long-term impact of your TNR efforts.

This is a quick way to model your colony's future without having to do complex calculations on your own. It is easy to adjust the parameters to reflect your specific situation — whether you're just getting started with TNR, managing an established colony, or making the case for increased resources in your community. Please check it out and see what you think.

The concept and calculations for this tool was created by Cory Piland, Grant Writer and Volunteer at Operation Catnip of Richmond, VA.

How does the Colony Population Projector work?

There are two ways to get your results. You can either download the spreadsheet, which includes detailed directions so you can work directly in excel. Just click the button below to start the download. Alternately, you can try out the handy app below and download your results. Start by naming your colony and entering the current number of cats — including how many are female and how many are male. In seconds, the projector will generate a 10-year population forecast based on national averages for reproduction, kitten survival, and attrition. Think those numbers don't match your colony's reality? Adjust the parameters to reflect your local conditions — your TNR rate, how many kittens are absorbed into homes, how often new cats join the colony, and more. The table updates automatically so you can see the long-term impact of your efforts in real time. Next, enter your email to have your results sent to you or download a spreadsheet to share with your team. Give it a try!

Download the Spreadsheet

Enter your colony's current population and adjust the parameters below to match your community's conditions. The projection table updates automatically to show estimated population year by year.

Estimated total, preferably via direct observation or caretaker input
Use 50% of total if unknown
Use 50% of total if unknown
Parameters & Assumptions (adjust to match your colony's conditions)

TNR & Adult Attrition

Rate at which adult cats undergo TNR and are returned to colony annually
%
Rate at which adult cats leave via rescue, adoption, relocation, or death annually
%
Rate at which new adult cats join the colony (lost, abandoned, or relocated) annually
%

Reproduction

Typically 2–3 per female per year
Average is 4 kittens per litter
Typically 50%; % male is calculated automatically
%
Automatically calculated as 100% minus % Kittens Female
50%

Kitten Survival

Kittens removed via adoption/rehab or lost to mortality before breeding age
%
Automatically calculated as 100% minus Humane Absorption & Mortality Rate
25%

Population Projection for My Colony

All figures rounded to the nearest whole number. Row totals may vary by ±1 due to rounding.

YearTotal CatsTotal FemalesTotal MalesFemales FixedMales FixedFemales IntactMales IntactTotal New KittensNew Kittens/yrNew Females/yrNew Males/yr

These projections are a general planning guide. Actual colony dynamics will vary based on local conditions, caretaker activity, and environmental factors.

Save or Share Your Projection

Download your inputs and projection table as a spreadsheet.

Email yourself a PDF summary of your projection.

Alright! What's next?

Sign up for a TNR Certification Workshop and learn to help manage out door cat populations or a Return to Home Certification Workshop and learn how to help more cats get back home!