Temperature Converter using HTML CSS and JavaScript

In this article, we will see Temperature Conversion between Celsius, Fahrenheit & Kelvin using HTML CSS & JavaScript. The Temperature is generally measured in terms of unit degree., i.e. in degree centigrade, in degrees, Fahrenheit & Kelvin.

• Celsius is a standard unit of temperature on the Celsius scale, & is represented by the °C symbol.
• Fahrenheit uses the degree Fahrenheit as the unit & is represented with the °F symbol.
• Kelvin is an internationally recognized standard for scientific temperature measurement. It is an absolute temperature scale that is obtained by shifting the Celsius scale by −273.15°, in order to coincide the absolute zero to 0K.

The following examples depict 0°C in Fahrenheit & Kelvin:

Input: 0 in Celsius
Output: 32 in Fahrenheit and 273.15 in Kelvin

Input: 0 in Fahrenheit
Output: -17.78 in Celsius and 255.37 in Kelvin

Input: 0 in Kelvin
Output: -273.15 in Celsius and -459.67 in Fahrenheit

The formula for converting Celsius scale to Fahrenheit scale and Kelvin scale:

T(°F) = (T(°C) * 9)/5 + 32
T(°K) = T(°C) + 273.15

The formula for converting Fahrenheit scale to Celsius scale and Kelvin scale:

T(°C) = ((T(°F) - 32) * 5) / 9
T(°K) = (T(°F)  - 32) * 5 / 9 + 273.15

The formula for converting Kelvin scale to Celsius scale and Fahrenheit scale:

T(°C) = (T(°K) - 273.15
T(°F) = (T(°K) - 273.15) * 9 / 5 + 32;

Approach:

• Create one container in which all the elements are present.
• Inside this container add 3 input fields in which one for Celsius and another for Fahrenheit and Kelvin.
• Now Style which you want I add this container in the center.
• Now added Javascript which converts the following Temperature(Fahrenheit, Celsius, Kelvin) to the corresponding Remaining Two Temperature prints results in the various input fields.

Example: This example illustrates the basic temperature Conversion between Celsius, Fahrenheit & Kelvin using HTML, CSS & JS.

HTML

<style>
    * {
        margin: 0;
        padding: 0;
        font-family: Verdana, Geneva, Tahoma, sans-serif;
    }

    .container {
        width: 100%;
        height: 100vh;
        background-image:
          linear-gradient(rgb(140, 219, 140), rgb(20, 141, 20));
        display: flex;
        flex-direction: column;
        justify-content: center;
        align-items: center;
    }

    .container h1 {
        color: green;
        font-weight: 700;
        font-size: 25px;
        text-align: center;
    }

    .converter-row {
        display: flex;
        width: 40%;
        justify-content: space-between;
        align-items: center;
        background: rgb(0, 56, 0);
        border-radius: 10px;
        padding: 50px 20px;
    }

    .col {
        flex-basis: 32%;
        text-align: center;
    }

    .col label {
        font-size: 15px;
        font-weight: 500;
        margin-bottom: 10px;
        color: #fff;
    }

    .col input {
        width: 150px;
        height: 30px;
        background: white;
        border-radius: 5px;
        text-align: center;
    }
</style>

<div class="container">
    <h1>GeeksforGeeks <br>
        Temperature Converter</h1>
    <div class="converter-row">
        <div class="col">
            <label>Fahrenheit</label>
            <input type="number" id="fahrenheit">
        </div>

        <div class="col">
            <label>Celsius</label>
            <input type="number" id="celsius">
        </div>

        <div class="col">
            <label>Kelvin</label>
            <input type="number" id="kelvin">
        </div>
    </div>
</div>

<script>
    let celsius = document.getElementById('celsius');
    let fahrenheit = document.getElementById('fahrenheit');
    let kelvin = document.getElementById('kelvin');
    celsius.oninput = function () {
        let f = (parseFloat(celsius.value) * 9) / 5 + 32;
        fahrenheit.value = parseFloat(f.toFixed(2));

        let k = (parseFloat(celsius.value) + 273.15);
        kelvin.value = parseFloat(k.toFixed(2));
    }
    fahrenheit.oninput = function () {
        let c = ((parseFloat(
            fahrenheit.value) - 32) * 5) / 9;
        celsius.value = parseFloat(c.toFixed(2));

        let k = (parseFloat(
            fahrenheit.value) - 32) * 5 / 9 + 273.15;
        kelvin.value = parseFloat(k.toFixed(2));
    }
    kelvin.oninput = function () {
        let f = (parseFloat(
            kelvin.value) - 273.15) * 9 / 5 + 32;
        fahrenheit.value = parseFloat(f.toFixed(2));

        let c = (parseFloat(kelvin.value) - 273.15);
        celsius.value = parseFloat(c.toFixed(2));
    }
</script>

Output: