# Typing values
> Type sums, units and variables into any number field, nudge with the arrow keys, or drag a field's icon to change its value.
Source: https://uxdeck.app/guide/typing-values (checked against uxdeck on 16 October 2026)
Every number field in the Design and Prototype tabs does more than take a number. You can type a small sum, write a value in another unit, pick a variable, nudge it with the arrow keys or drag it. This page covers how.
## Do the maths in the field
Type a sum and the field keeps the answer. `8*2` becomes 16, `24 + 4` becomes 28, `(1440 - 48) / 3` becomes 464.
- You can use `+`, `-`, `*`, `/` and brackets. `x`, `×` and `÷` work too.
- A comma is read as a decimal point, so `1,5` is 1.5.
- A sum that does not make sense (or divides by zero) is ignored, and the field goes back to its value.
## Enter, Tab and Escape
- ↩ applies the value and keeps the field selected, so you can type again or move on.
- ⇥ goes on to the next field.
- Esc forgets what you typed and leaves the field.
## Arrow keys
In a field, ↑ and ↓ change the value by 1, and with ⇧ by 10. Each press applies at once. In a field shown in rem or em, the steps are 0.1 and 1.
## Drag to change a value
Drag the icon or letter at the start of a field (the **W**, the **X**, the radius icon) left or right to change the value. Hold ⇧ while you drag for steps of 10. The whole drag is one undo.
## Units for type
**Font size**, **Line height** and **Letter spacing** show a unit at the end of the field. Press it to switch:
| Field | Units |
|---|---|
| Font size | px, rem, em |
| Line height | px, %, em |
| Letter spacing | %, px, em, rem |
You can also type the unit with the number. In a field that offers it, the field switches to that unit (`-1px` in letter spacing shows -1 px). A unit the field does not offer is converted into the field's own unit. rem and em are measured against 16 px.
Units change only how the value reads: the layer keeps the same size whichever you look at, and your choice of unit stays for the next layers you select. Line height also takes the word `auto`.
## Use a variable
Type = in a number field to open the variables that fit it, or press the hexagon button (**Apply variable**) at the end of the field. From the picker you can:
- pick a variable, and the field follows it from then on;
- **Search variables** by name;
- **Create variable** from the value the field shows now;
- **Detach variable**, keeping its current value.
A field that follows a variable shows its name. The button only appears where the file has variables that fit, or where one can be made. See [Variables and modes](/guide/variables).
## Several layers at once
With several layers selected, a field whose value differs between them reads **Mixed**. Type a number and every layer takes it. See [Edit several layers at once](/guide/edit-several).
## Catches
- **Sums use the field's unit.** A plain number in a sum is read in the unit the field shows, so in a font size shown in rem, `1.5*2` gives 3 rem.
- **Two units in one sum** (`1rem + 4px`) keep the field's unit and convert both.
- **Only numbers and the signs above.** Words, percentages of a parent or CSS functions are not understood; the field goes back to its value.
- **The unit you choose belongs to this browser.** On another computer, the fields start in px (or % for letter spacing).