Round to the Nearest Thousandth Calculator

Created by Luis Hoyos
Reviewed by Davide Borchia
Last updated: Jan 26, 2023

If you're searching for how to round to the nearest thousandth, this calculator is the tool you need. Input the number to round, and the calculator will provide the result.

If you want to look at various examples of rounding to the nearest thousandth, look at the lowest part of the calculator. Additionally, in the following section, we present how to perform the rounding process manually, and in the FAQ section, an example of rounding 38.7165 to the nearest thousandth.

How to round to the nearest thousandth? (and examples)

Rounding to the nearest thousandth implies approximating to three decimals by following these steps:

  1. Identify the digit at the thousandth position (always the third digit after the decimal point);
  2. Identify the number to the right of the thousandth position; and
  3. Apply the following rules:
    • If the number to the right of the thousandth position is lower than 5, we leave the thousandth position as it is. E.g., -0.1233 ≈ -0.123
    • If the number to the right of the thousandth position is 5 or greater, we round up the thousandth digit. E.g., -0.1237 ≈ -0.124.
      • Additionally, if the number to round (the third decimal) is 9, we change it to zero and increase the second decimal by one unit. E.g., $3.0795 ≈ $3.080 and $2.719212 ≈ $2.720.
      • We do the same for the second and first decimals if they are 9. E.g., $3.0995 ≈ $3.100 and $2.999212 ≈ $3.000.

The rule in the third step is known as the half up rounding mode, the most common in math. Even so, there are other modes, which you can enable in the advanced mode of the calculator (learn more about them in our rounding calculator).

💡 If the number has fewer than three decimal digits, you don't need rounding, as there is no thousandth! However, you can pad the number with trailing zeros: even so, depending on the situation, those additional zeros could create false precision, as they could not represent true significant figures. Look at the significant figures Wikipedia article to learn how they relate to trailing zeros.

Number

Approximation

-0.13

≈ -0.13 or -0.130

-0.1

≈ -0.1 or 0.100

-0.12

≈ -0.12 or -0.120

0.46

≈ 0.46 or 0.460

0.4

≈ 0.4 or 0.400

0.45

≈ 0.45 or 0.450

7

≈ 7 or 7.000

9

≈ 9 or 9.000

10

≈ 10 or 10.000

FAQ

What is 38.7165 rounded to the nearest thousandth?

38.7165 rounded to the nearest thousandth is 38.717. To come to this answer:

  1. Identify the third digit after the decimal point (the thousand digit):
    • In this case, it's 6.
  2. Identify the number to the right of the thousandth digit:
    • In this case, it's 5
  3. As the number to the right of the hundredth digit is 5, we round up the hundredth digit from 6 to 7. The answer is 38.717.

How do I solve 4x - 3 = 18 and round it to the nearest thousandth?

To solve 4x - 3 = 18 and round it to the nearest thousandth:

  1. Add 3 to both sides of the equation:
    • 4x -3 + 3 = 18 + 3 ⇒ 4x = 21
  2. Divide both sides by 4:
    • 4x/4 = 21/4 ⇒ x = 21/4
  3. Express x as a decimal:
    • x = 21/4 = 5.25.
  4. Use our calculator to round to the nearest thousandth; in this example, the answer is x = 5.25 or x = 5.250.

What is 0.333 rounded to the nearest thousandth?

0.333 rounded to the nearest thousandth is 0.333 (the same number) because rounding to the nearest thousandth implies keeping a precision of three decimals, which already exists for 0.333.

Luis Hoyos
Number
Result
For non-standard rounding modes check out the advanced mode.
Example
NumberApproximation
-0.1237-0.124
-0.1235-0.124
-0.1233-0.123
0.45670.457
0.45650.457
0.45630.456
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