> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/obsidianmd/obsidian-help/llms.txt
> Use this file to discover all available pages before exploring further.

# Formulas

> Formulas are computed columns in Bases. Use them to calculate values, combine fields, work with dates, and apply conditional logic — all from your note properties.

Formulas let you create calculated properties in Bases using data from other properties. A formula property doesn't exist in your notes' frontmatter — it's computed on the fly from values that do.

## What formulas can do

* **Calculate values** — add prices, compute totals, perform math operations.
* **Manipulate text** — combine strings, change case, extract substrings.
* **Work with dates** — calculate time differences, format dates, determine deadlines.
* **Apply logic** — use conditional statements to display different values.
* **Process lists** — filter, sort, map, or aggregate list data.

## Create a formula property

<Steps>
  <Step title="Open the Properties menu">
    In your base, click **Properties** in the toolbar.
  </Step>

  <Step title="Add a formula">
    Click **Add formula** at the bottom of the menu.
  </Step>

  <Step title="Name and define the formula">
    Enter a name for the formula property and type your formula expression in the **Formula** field.
  </Step>

  <Step title="Save">
    Close the dialog. A green checkmark confirms the formula is valid.
  </Step>
</Steps>

Once created, a formula property works like any other property: add it to views, filter by it, sort by it, and more.

## Write a formula

A formula is an expression that combines properties, operators, and functions.

### Reference properties

You can reference three types of properties:

| Type                        | Syntax                                  | Example                  |
| --------------------------- | --------------------------------------- | ------------------------ |
| Note property (frontmatter) | `property_name` or `note.property_name` | `price`, `note.price`    |
| File property               | `file.name`, `file.size`, `file.mtime`  | `file.mtime`             |
| Another formula             | `formula.formula_name`                  | `formula.price_per_unit` |

**Examples:**

```js theme={null}
price * quantity
file.name + " - " + description
formula.price_per_unit * 1.1
```

### Operators

**Arithmetic:**

```js theme={null}
price + tax
price - discount
price * quantity
price / quantity
(part / whole) * 100
```

**Comparison** (return `true` or `false`):

```js theme={null}
price > 100
age < 18
status == "Done"
status != "Done"
file.mtime > now() - '7d'
```

**Boolean:**

```js theme={null}
!completed
price > 0 && quantity > 0
urgent || important
```

### Functions

Functions perform operations on values. The available functions depend on the value type. See the full function list in [Bases syntax](/bases/syntax).

| Category | Examples                                                         |
| -------- | ---------------------------------------------------------------- |
| Global   | `if()`, `now()`, `today()`, `date()`, `link()`, `max()`, `min()` |
| String   | `contains()`, `replace()`, `split()`, `lower()`, `title()`       |
| Number   | `round()`, `ceil()`, `floor()`, `abs()`, `toFixed()`             |
| Date     | `format()`, `relative()`, `date()`, `time()`                     |
| List     | `filter()`, `map()`, `sort()`, `join()`, `unique()`              |

## Formula examples

<AccordionGroup>
  <Accordion title="Calculate a deadline">
    Set a project's due date to 2 weeks after the start date:

    ```js theme={null}
    start_date + "2w"
    ```
  </Accordion>

  <Accordion title="Display overdue status">
    Show "Overdue" if the due date has passed and the task isn't done:

    ```js theme={null}
    if(due_date < now() && status != "Done", "Overdue", "")
    ```
  </Accordion>

  <Accordion title="Format currency">
    Display a price with two decimal places and a currency symbol:

    ```js theme={null}
    if(price, "$" + price.toFixed(2), "")
    ```
  </Accordion>

  <Accordion title="Count list items">
    Count the number of items in a list property:

    ```js theme={null}
    tasks.length
    ```
  </Accordion>

  <Accordion title="Calculate a priority score">
    Combine multiple factors into a single score:

    ```js theme={null}
    (impact * urgency) / effort
    ```
  </Accordion>

  <Accordion title="Combine text fields">
    Create a full name from first and last name properties:

    ```js theme={null}
    first_name + " " + last_name
    ```
  </Accordion>

  <Accordion title="Calculate total cost">
    Multiply a monthly cost by the number of months, using another formula:

    ```js theme={null}
    monthlyUses * formula.Owned.round()
    ```
  </Accordion>
</AccordionGroup>

## Data types

Formulas work with these data types:

| Type    | Description        | Examples                                     |
| ------- | ------------------ | -------------------------------------------- |
| String  | Text in quotes     | `"hello"`, `'world'`                         |
| Number  | Numeric values     | `42`, `3.14`                                 |
| Boolean | True or false      | `true`, `false`                              |
| Date    | Date or datetime   | Created with `date()`, `today()`, or `now()` |
| List    | Ordered collection | `[1, 2, 3]`                                  |
| Object  | Key-value pairs    | `{"name": "value"}`                          |

The output type of a formula is determined by the data and functions used.

## Reference other formulas

Formulas can reference other formula properties to build derived calculations:

```js theme={null}
// Formula: price_per_unit
price / quantity

// Formula: total_with_markup — references price_per_unit
formula.price_per_unit * 1.1
```

<Warning>
  A formula cannot reference itself directly or indirectly through other formulas. Circular references will produce an error.
</Warning>