The drawing system
Every answer, read off an instrument.
Each calculator ends in a drawing made from your numbers — a growth chart, a bowl filled to the real amount, a ruler of days. Here is how to read them, and the rules we hold them to.
Drawn to scale, from your numbers
Nothing here is a picture scaled down to fit. Each drawing is laid out from the numbers at the real width of your screen, one unit to one pixel, every time the page changes size or you change a number. A bowl that holds 1.40 cups is filled to where 1.40 cups would sit in that bowl; a day on the calendar is a real day; the dose ruler’s marks sit at the published thresholds.
Darker ink means surer
Every drawing uses the same five marks, with the same meaning on every page:
- A solid ink line or dot — what you measured, or the most likely value.
- A soft clay field — the middle half: where half of pets like yours end up, or a guideline range.
- A hatched field — 8 in 10, the published spread, or a window of days.
- A moss dashed line — time: today, or the days to take a temperature.
- An oat field or fine line — a reference you can compare with, such as the centile lines on a growth chart.
- most likely
- middle half
- 8 in 10
- today
- most likely day
- the window
- today, temperature checks
Never colour alone — and no colour means “good”
Every mark also has a position, a pattern and a word, so the drawings read in black and white, on paper and for people who see colour differently. There is no green zone anywhere on this site and no colour that means “fine”: moss means time, never health. On the chocolate dose ruler the part below the first published mark is labeled “still call”, because no amount of chocolate is a reason not to call.
- a numbered flag where something happened (a line crossed on the growth chart)
Labels never cross
Every label is measured before it is placed. When two would touch, they move apart and a thin leader line points back to the true spot; tiny amounts get a minimum visible size while the label keeps the true value. An automated test lays out every drawing with extreme numbers at widths from a small phone to a wide desktop, and at larger text sizes, and fails if any label is crossed, clipped or overlapped.
Our own drawings
The drawings are our own design, built from openly licensed data and published figures. They are not traced from, and do not copy the layout of, any published growth chart, body-condition chart or age chart. The data behind each one is listed with its licence on Data and sources.