How to adjust MUI Tooltip font size?

Question

I implemented a tooltip with MUI but the fontSize is too small. And I can't change it with a .scss.

import React from "react";
import "./InfoTooltip.scss";
import InfoIcon from '@material-ui/icons/Info';
import Tooltip from '@material-ui/core/Tooltip';

const InfoTooltip: React.FC<{ children?: any }> = ({ children }) => {
  const [label, ...rest] = children;
  return (
    <div className="info-tooltip-container">
      <div className="label-container">
        <Tooltip title={label}>
          <InfoIcon style={{ fontSize: '24px' }} />
        </Tooltip>
      </div>
      {rest}
    </div>
  );
};

export default InfoTooltip;

.info-tooltip-container {
  .label-container {
    font-size: 18px;
  }
  label {
    font-size: 18px;
  }
}

https://mui.com/components/tooltips/#main-content

Answer 1

You can add a customized component directly to props title.

If needed, you can add whatever inline-styles to the component you just added.

Include the font-size

<Tooltip title={<h1 style={{ color: "lightblue" }}>title</h1>}>
  <InfoIcon />
</Tooltip>

---

Refer: MUI tooltip document: customized-tooltips

Answer 2

You can do that at global level or at component level.

Global level

This way all the Tooltips in the application will get the style.

First you need to create a theme.js file:

'use strict';

import { createMuiTheme } from '@material-ui/core/styles';

const theme = createMuiTheme({
    overrides: {
        MuiTooltip: {
            tooltip: {
                fontSize: "1em",
            },
        },
    },
});

export default theme;

Then import it in your main application component, so it will be applied to all the application components:

'use strict';

import React from "react";
import { ThemeProvider } from '@material-ui/styles';
import CssBaseline from '@material-ui/core/CssBaseline';
import theme from 'theme.js';

export default class App extends React.Component {

    render() {
        return (
            <ThemeProvider theme={theme}>
                <CssBaseline />
                    {/* Your app content */}
            </ThemeProvider>
        );
    }
}

Component level

With this approach you can define a different style for each component.

'use strict';

import React from "react";
import { makeStyles } from '@material-ui/core/styles';
import Tooltip from "@material-ui/core/Tooltip";

const useStyles = makeStyles({
    tooltip: {
      fontSize: "1em",
    },
});

export default class MyComponent extends React.Component {

    const classes = useStyles();

    render() {
        return (
            <Tooltip classes={{tooltip: classes.tooltip}} />
        );
    }

}

Answer 3

You can also use Typography and set the fontSize directly. Some components like Box or Typography inherit system props which allow you to change the styling using the top-level props:

<Tooltip title={<Typography fontSize={30}>title</Typography>}>
  <IconButton>
    <DeleteIcon />
  </IconButton>
</Tooltip>

Live Demo

Answer 4

Using MUI v5

This will change the font size for all tooltips within <ThemeProvider>

import React from "react";
import { createTheme, CssBaseline, ThemeProvider } from '@mui/material';

const theme = createTheme({
    components: {
        MuiTooltip: {
            styleOverrides: {
                tooltip: {
                    fontSize: '1em'
                }
            }
        }
    }
});

export default function App() {
    return <ThemeProvider theme={theme}>
        {/* Your app content */}
        <CssBaseline />
    </ThemeProvider>;
}