Our methodology

Facts come from official sources: government bodies, regulators, recognised professional bodies, or a maker's published sheet. Each planner lists its sources with the date they were last checked. Where a planner uses a rule of thumb, it says so.

If no official source gives a value, we do not guess one. If sources disagree, the planner is not published until the question is settled. We name diseases and types of product, never brands.

Week N means the birth date plus N times seven calendar days. Months are whole weeks divided by 4.33, rounded down. Dates are calculated as calendar days, so daylight saving changes never move a planned date. Today's date comes from your device.

Before a planner is published, its calculations are tested against a worked example with known answers, including dates and time zones where they matter. A passing test checks the arithmetic. It does not make a date right for every puppy, so check plans with your vet.

A page goes live only after it passes its checks. Pages with open source questions are left out of the site and its links. An article goes live only once the planner it supports is live.