The **ceil()** is a built-in **math** module function in **Python** that **“rounds up a number to the nearest integer and returns the result”**. The **ceil()** method accepts only one input value, the numeric value, and returns the rounded-up value to the nearest integer.

To round up numbers in Python, you can use the **“math.ceil()”** function.

**What does it mean to round up?**

To **round** **up** means you round a number to **the closest integer**. This means if your given number is 5.1. it will round up to 6.

When you round up a number, **you round the number to the closest integer greater than the number**.

**The time complexity of ceil() function**

The **ceil()** function has a time complexity of **O(1)**, which means it takes a fixed amount of time to execute regardless of the size of an input value.

**How to use ceil() function?**

To use the **ceil()** **function** in **Python**, import the math module.

**Syntax**

`math.ceil(num)`

**Parameter values**

The **math.ceil()** function accepts a **num **as an argument.

**Return value**

The **ceil()** function returns an int value representing the rounded number.

**Example 1**

```
import math
print(math.ceil(1.9))
print(math.ceil(2.1))
print(math.ceil(11.1))
print(math.ceil(21.19))
```

**Output**

```
2
3
12
22
```

You can see that the **ceil()** function rounds up the **1.9 number to 2. **Then, **2.1 to 3, 11.1 to 12, **and **21.19 to 22.**

**How to round up to 2 decimal places using ceil()**

To **round** up **two** **decimal** **places** in **Python**, you can use the **“math.ceil()”** function.

```
import math
num = 0.222222222000
num = math.ceil(num * 100) / 100.0
print(num)
```

**Output**

`0.23`

You can see that we rounded up to two decimal places from 0.22222222000 to 0.23.

**What is the difference between Python floor() and ceil()?**

The **main** **difference** **between** the **“floor()”** and “**ceil()”** functions is that **floor()** function **rounds down** to its nearest integer value, and ceil() function rounds up to its nearest integer.

**Pros and Cons of ceil() function**

**Pros**

- It has a fast execution time.
- The
**math.ceil()**is a built-in function, so you don’t need to install other libraries. - The
**math.ceil()**is not a complex function with many arguments; it is an easy-to-use function that takes several arguments and returns the result.

**Cons**

- It rounds up to the nearest integer, which you can’t do with other types of rounding.
- You can use either the
**“floor()”**or**“round()”**function for other rounding tasks because ceil() is not useful for every scenario.

That’s it.