Rounding calculator
How can this rounding numbers calculator help you?
Rounding values to the nearest significant figure may seem as a simple task. In many cases it is. Approximating a fractional decimal number to the nearest natural number is simple even for kids.
If you try rounding up 8957303479453 to the nearest billion then using our tool will be helpful.
Our website will help you with:
Rounding whole numbers
This tool will help you approximate natural numbers to the nearest hundreds, thousands, million or billion.
Rounding decimals
Our rounding decimals calculator will not only allow you to perform standard rounding, but also:

Rounding up

Rounding down

Rounding towards zero

Rounding away from zero

Rounding mixed numbers
This type of computation may be tricky, but you can simply convert a mixed number to decimal and round it using the form above.
Useful calculator for rounding decimals to the nearest whole numbers, tenth, hundredth or a thousandth.
Rounding Methods
There are many different rounding modes and you should be aware of them to properly choose your approximation technique.
Half up
This is the most common form of approximating values and the way you were used to round at school. This method rounds the decimal number to the nearest natural number. If the fraction part is equal or greater than .5 then the value goes up. Otherwise the value goes down. Let’s see examples:

1,5 => 2

1,51 => 2

1,49 => 1
Half down
This is a close variation of the previous method. The only difference is that the fraction part must be greater than .5 in order to be able to increase the value. Check the examples:

1,5 => 1 (opposite behavior)

1,51 => 2

1,49 => 1
Round up (ceiling)
This is a very convenient method when you want to approximate a decimal to the next closest natural number.

1,5 => 2

1,51 => 2

1,49 => 2

1,01 => 2
Round down (floor)
There is an opposite method to the previous one. When you want to approximate decimal to the previous closest natural number. In other words, you simply want to cut off fractional parts by removing numbers after the decimal point.

1,99 => 1

1,51 => 1

1,49 => 1

1,01 => 1
Round half to even
This is the less common method, when the value is approximated not to the nearest integer but to the nearest even number. Let’s see some examples:

1,99 => 2

2,51 => 4

2,49 => 2

3,49 => 2
Round half to odd
Very similar to the rule described before, with a distinction that values are rounded to the nearest odd integer.

1,99 => 3

2,51 => 3

2,49 => 1

3,49 => 3
This and previous procedure is also known as tie breaking rules.
Round half toward zeros
This method approximates positive and negative symmetrically, with zero as a bias. For example 2.1 gets rounded to 2 and 2.1 is rounded to 2.
This method is also called round half away from infinity.
Round half away from zero
This is the opposite behavior to the previous one. The positive and negative numbers are rounded symmetrically with zero as a bias. This method is also called round half toward infinity. For a given number:

2.1 => 3

 2.1 => 3
You may be surprised by the fact that it is actually a very popular method for rounding prices and in currency conversion thus it’s also known as commercial rounding.
Sig Fig Rounding Calculator
Rounding to the nearest significant figure is very useful in real life as in some situations we care about the most important figures when comparing numbers.
For example when comparing maximum ship payload we care about the number of tons not kilograms, therefore you need to round to max ship capacity to the nearest thousand.

Round to the Nearest Whole

Round to the Nearest Ten

Round to the Nearest Hundred

Round to the Nearest Thousand

Round to the Nearest Million
Digits after decimal point
Often not all decimal places are important. In order to simplify the comparison it is common practice to just cut off not necessary digits, after the comma.
The most common cases are:

Round to the Nearest Hundredth

Round to the Nearest Thousandth
The plentiness of use cases makes it one most common method, not only for approximating traditional money amounts, but for cryptocurrencies as well where even digits to the right of hundred thousandths are important.
Summary
Now one you are familiar with different ways of comparing numbers, you can select the desired rounding procedure in our free online tool and perform your own calculations.
This may seem as a boring topic, but understanding it properly will prevent you from making many mistakes when comparing numbers and help you with data analysis. If you need to dive in to this topic we recommend you reading this Wikipedia article.
Authors
Created by Lucas Krysiak on 20220321 16:53:53  Last review by Mike Kozminsky on 20220917 16:44:48