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Formulas

A Formula Property computes a value from your other fields — a BMI from height and weight, a countdown from two dates, a label from a number. Read-only, and it updates itself the instant a field it uses changes.

A Formula is a read-only Property that computes its value from your Entry's other Properties, Notion-style. Type an expression once — prop("Weight kg") / prop("Height m") — and every Entry shows its own answer, recalculated live whenever the fields it uses change.

It's the third Computed Property kind, alongside Rollup and Portion. Where a Rollup totals up an Entry's sub-entries, a Formula reads fields on the same Entry.

Add a Formula

  1. In the Collection builder, add a Property and pick Formula from the Computed group.
  2. Type your expression. Tap a sibling field's name-chip to insert prop("Field name") instead of typing it out.
  3. Choose the output — Number, Text, Checkbox, or Duration — so Kaizendex knows how to format the result.
  4. The editor shows a live preview as you type, so you can check the math before saving.

That field now shows its computed value, read-only, on the card, the Entry page, and the table — for every Entry of that Collection.

Writing an expression

Reference another field on the same Entry with prop("Its Name") — the name it shows in the builder. Combine fields with ordinary math (+ - * / %), comparisons (== != < <= > >=), and and / or / not.

A handful of functions cover the rest:

FunctionDoes
if(condition, then, else)Branches on a condition
round(x[, digits]), floor(x), ceil(x), abs(x)Rounding and absolute value
min(...), max(...)Smallest / largest of a list
dateBetween(later, earlier, "minutes"|"hours"|"days")The gap between two date/time fields
now()The current moment
empty(x)True if a field is blank
concat(...), length(text)Join text together, or measure it

Examples

BMI, from a Weight and Height field:

round(prop("Weight kg") / (prop("Height m") * prop("Height m")), 1)

Output: Number.

A label that reacts to a number:

if(prop("Reps") >= 10, "Strong set 💪", "Keep going")

Output: Text.

Sleep time, from a Bedtime and Wake time field:

dateBetween(prop("Wake time"), prop("Bedtime"), "minutes")

Output: Duration — renders as 7h 42m. This is exactly how the built-in Sleep time field works on a connected wearable's Sleep collection: subtract Bedtime from Wake time and show the gap.

A simple pass/fail check:

prop("Steps") > 10000

Output: Checkbox.

A blank or broken result

If a field a Formula depends on is empty, the Formula usually reads as blank rather than erroring — use empty(prop("Field")) to test for that explicitly and branch with if(...). A genuinely broken expression (a typo'd field name, mismatched types) shows a short error marker on the card and table, and the full message on the Entry page so you can fix it.

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