How old is your dog, really? How big will they get? Built for curious owners, shelter volunteers, and anyone who loves a good dog mystery.
Teeth, weight, height — combined into one honest estimate.
The highest-confidence metric. Tooth eruption and wear follow precise timelines. Log individual teeth observations with dates for maximum accuracy.
Plot weight and height measurements over time. We overlay your data on breed-specific reference charts sourced from veterinary literature.
Mixed-breed dogs get weighted averages of each parent breed's growth model. Supports unlimited breed combinations with custom percentage sliders.
Early spay/neuter can affect how tall a dog grows. We account for this when projecting adult size.
Every breed's growth curve is sourced from AKC standards and published veterinary studies — not guesswork.
Your progress autosaves on your device while you work, and you can export the full record as CSV or PDF and re-import it later from any browser.
Ace came home from a shelter in early 2026 with more questions than answers. His birthday was only a best guess, and like a lot of rescue dogs, his early history was mostly blank space.
I wanted to know whether the shelter's estimated birthday was close, but that was only half of it. I was also trying to understand Ace's growth. Was he going to stay medium-sized, grow into those paws, or surprise everyone and become a full-sized couch horse? The only way to get closer was to start tracking the clues in front of me: teeth, weight, height, and breed mix.
So I started logging what I could. Each new entry sharpened the estimate, and over time, the data began to line up surprisingly close to the shelter's best guess.
That curiosity became PawSizer.
It's a simple tool for estimating your dog's age, projecting growth, and keeping their development data in one place. No account, no ads, no catch. Just a clearer picture of where your dog is in their story.
Takes about 5 minutes. Works with whatever data you have — even a single weight measurement helps.
No sign-up. No email. Just open it and go.
Returning user? to pick up where you left off.
How it works and why I built it.
PawSizer works by testing hundreds of candidate birth dates and scoring each one against your observations — dental stage, growth measurements, and any known date. Whichever date best fits everything you've entered wins. The more observations you add, the narrower the answer gets.
Standard MLE finds the most probable date given the data. PawSizer adds four layers on top of that:
PawSizer is a curiosity tool, not a veterinary diagnosis. Estimates are best guesses based on the data you enter — individual dogs vary, and nothing here replaces a conversation with your vet.
PawSizer is proprietary software, copyright © 2026–present, all rights reserved. Free for personal, rescue, and veterinary reference use. See the Terms of Service for full details on acceptable use, intellectual property, and liability.
What we collect, why, and what choices you have.
Last updated: 2026-05-09
PawSizer is a free tool for estimating a dog's age and adult size from observations you enter. Most of what you type stays on your device. We use Microsoft Clarity for usage analytics, but only if you grant consent. We never sell your data, run ads, or build a profile of you. If something here is unclear, email feedback@pawsizer.com.
PawSizer is operated by Daniel M. as a personal project. The site is hosted on Oracle Cloud infrastructure in the United States. PawSizer is currently in Public Beta.
Like every website, our server records standard access logs: IP address, timestamp, the page or endpoint requested, and your browser's user-agent string. These logs are used for security monitoring, debugging, and rate-limiting. They are retained for 14 days and then automatically deleted via standard log rotation. Request bodies (the data you submit when you click Calculate) are not logged.
After receiving an estimate, you can optionally submit feedback to help calibrate the algorithm. This is opt-in only — nothing is stored unless you click submit.
Feedback records are retained indefinitely. The dog data (breeds, weights, dental observations, height, body condition) directly improves the algorithm's accuracy for future users — this is the core reason PawSizer can get better over time.
If you opted into the 6-month follow-up, your email address is retained alongside your record until the follow-up is sent or you request deletion, whichever comes first.
We use Microsoft Clarity to understand how people navigate PawSizer — which steps they complete, where they get stuck, what's confusing. This helps us improve the tool.
Clarity is loaded only after you grant consent through the banner shown on your first visit. If you decline, Clarity is never loaded. Clarity automatically masks personal information and form input content by default — it does not record the breed, weights, or other data you enter.
Clarity collects anonymized session recordings (mouse movement, clicks, scroll depth), device class, country/city-level geography, and referrer information. Microsoft retains this data per their own policies (typically around 30 days for session recordings). See Microsoft's privacy statement for details.
If your browser sends a Do Not Track signal, we automatically decline analytics consent on your behalf — Clarity is never loaded, and the consent banner does not appear. You can still submit feedback if you choose; DNT only affects analytics.
PawSizer itself does not set any cookies. We use your browser's localStorage to save your assessment progress (so you can resume) and your analytics consent choice. If you grant analytics consent, Microsoft Clarity sets its own cookies; declining means none are set. Clearing your browser's site data for pawsizer.com removes everything.
A few external services are used to render the site and see your IP address as a normal part of HTTPS requests. They do not receive any of your assessment data:
PawSizer is not directed at children under 13 and we do not knowingly collect data from children. If you believe a child has submitted feedback through PawSizer, email feedback@pawsizer.com and we'll remove the entry.
Our server is located in the United States. If you are in the EU, UK, California, or another jurisdiction with data protection laws, your data is transferred to and stored in the US. You retain the rights granted under your local law (such as access, correction, and deletion); contact feedback@pawsizer.com to exercise them.
We may update this policy as PawSizer evolves. Material changes will be noted at the top of this page with a new "Last updated" date. For significant changes affecting existing feedback records, a notice will appear on the site for 30 days.
The rules for using PawSizer.
Last updated: 2026-05-09
PawSizer is a free web tool for estimating a dog's age and projected adult size from observations the user enters. It is operated by Daniel M. as a personal project and is currently in Public Beta — the algorithm is under active validation, and results are estimates only.
PawSizer's outputs are estimates produced by a statistical model, not medical or veterinary diagnoses. Do not use PawSizer to make health, breeding, or treatment decisions for your dog. For any health concern, consult a licensed veterinarian.
The algorithm is calibrated against published growth and dental literature, but individual dogs vary, and the tool cannot replace professional examination.
PawSizer — including its source code, MLE algorithm, breed reference data, dental staging model, and all design, copy, and visual assets — is proprietary intellectual property of Daniel M. All rights reserved.
Copyright © 2026–present PawSizer.
To request permission for any use not listed in the Acceptable Use section above, contact feedback@pawsizer.com.
See the Privacy Policy for what we collect and how it's handled. In short: data you enter into the tool stays on your device unless you click Calculate or submit feedback, and we do not sell or share your data.
You are responsible for the accuracy of data you enter — garbage in, garbage out. The algorithm cannot detect typos or fabricated observations and will produce estimates based on whatever you submit.
PawSizer is provided "as-is" with no warranty of any kind, express or implied. We do not guarantee accuracy, availability, or fitness for any particular purpose. Features may be added, removed, or changed at any time.
To the maximum extent permitted by law, the operator of PawSizer is not liable for any direct, indirect, incidental, or consequential damages arising from your use of PawSizer or reliance on its outputs. This includes but is not limited to: incorrect age estimates, incorrect size projections, decisions about adoption or care made based on PawSizer's output, or service downtime.
If you disagree with this limitation, your sole remedy is to stop using PawSizer.
PawSizer runs on a single server and may be unavailable for maintenance, updates, or unforeseen reasons. We do not commit to any uptime guarantee.
PawSizer does not require an account. There is no login, password, or profile. Your assessment data lives in your browser; closing the tab without exporting means losing it.
We may update these terms as PawSizer evolves. Material changes will be noted at the top of this page with a new "Last updated" date. Continued use after changes constitutes acceptance.
These terms are governed by the laws of the State of New York, United States. Any dispute arising out of or relating to PawSizer or these terms shall be resolved in the state or federal courts located in New York.