Round to the Nearest Thousandth Calculator

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.

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. For example, -0.1233 ≈ -0.123.

   • If the number to the right of the thousandth position is 5 or greater, we round up the thousandth digit. For example, -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. For example, $3.0795 ≈ $3.080 and $2.719212 ≈ $2.720.

     • We do the same for the second and first decimals if they are 9. For example, $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 by ticking the "Show advanced rounding modes" option in the 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.

Now that you know how to round to the nearest thousandth, these calculators may also interest you:

• Round to the nearest hundred calculator;
• Round to the nearest hundredth calculator;
• Round to the nearest ten calculator;
• Round to the nearest tenth calculator;
• Round to the nearest cent calculator;
• Round to the nearest dollar calculator;
• Round to the nearest penny calculator; and
• Round to the nearest integer calculator.