react-test/docs/data/material/customization/spacing/spacing.md

Spacing

Use the theme.spacing() helper to create consistent spacing between the elements of your UI.

Material UI uses a recommended 8px scaling factor by default.

const theme = createTheme();

theme.spacing(2); // `${8 * 2}px` = '16px'

Custom spacing

You can change the spacing transformation by providing:

• a number

const theme = createTheme({
  spacing: 4,
});

theme.spacing(2); // `${4 * 2}px` = '8px'

• a function

const theme = createTheme({
  spacing: (factor) => `${0.25 * factor}rem`, // (Bootstrap strategy)
});

theme.spacing(2); // = 0.25 * 2rem = 0.5rem = 8px

• an array

const theme = createTheme({
  spacing: [0, 4, 8, 16, 32, 64],
});

theme.spacing(2); // = '8px'

:::warning Note that when spacing is defined as an array, it only works with positive integers that will be used as array indexes.
It doesn't support all possible signatures of the theme.spacing() helper, for example theme.spacing(0.5), theme.spacing(-1), or theme.spacing(1, 'auto').

If you must use spacing array, consider using a function signature that can handle all possible signatures of the theme.spacing() helper:

Spacing function example

const spacings = [0, 4, 8, 16, 32, 64];

const theme = createTheme({
  spacing: (factor: number | 'auto' = 1) => {
    if (factor === 'auto') {
      return 'auto';
    }
    const sign = factor >= 0 ? 1 : -1;
    const factorAbs = Math.min(Math.abs(factor), spacings.length - 1);
    if (Number.isInteger(factor)) {
      return spacings[factorAbs] * sign;
    }
    return interpolate(factorAbs, spacings) * sign;
  },
});

const interpolate = (value: number, array: readonly number[]) => {
  const floor = Math.floor(value);
  const ceil = Math.ceil(value);
  const diff = value - floor;
  return array[floor] + (array[ceil] - array[floor]) * diff;
};

:::

Multiple arity

The theme.spacing() helper accepts up to 4 arguments. You can use the arguments to reduce the boilerplate.

-padding: `${theme.spacing(1)} ${theme.spacing(2)}`, // '8px 16px'
+padding: theme.spacing(1, 2), // '8px 16px'

Mixing string values is also supported:

margin: theme.spacing(1, 'auto'), // '8px auto'