Rounding Calculator
Enter a number and the calculator rounds it to decimal places, significant figures and common nearest values all at once.
Precision & Significant Figures Rounder
Rounded Values
How rounding works
Rounding replaces a number with a nearby value that is simpler but close in size. The usual rule is to look at the digit just after the rounding position: if it is 5 or more, round up; otherwise round down.
For example 1234.5678 rounded to 2 decimal places becomes 1234.57, and to the nearest ten it becomes 1230. The calculator applies this rule consistently to every rounding target.
Decimal places vs significant figures
Decimal places count digits after the decimal point. Significant figures count all meaningful digits from the first non-zero digit. The number 0.0045 has two significant figures but four decimal places.
Significant figures matter in science and engineering because they reflect measurement precision: 12.30 implies more precision than 12.3. The calculator shows both styles side by side.
How to use this calculator
- Enter the number you want to round.
- Set the number of decimal places and significant figures.
- Press Round to see both, plus common nearest-value results.
- Use the result that fits your context (money, measurement, statistics).
Pro tips
- For money, round to 2 decimal places.
- For statistics, report significant figures based on instrument precision.
- Rounding to the nearest 0.5 is handy for half-point grades and measurements.
Advantages & considerations
✅ Advantages
- Shows many rounding targets at once
- Supports significant figures
- Round-half-up rule matches everyday expectations
⚠️ Considerations
- Uses the standard half-up convention only
- Rounding can accumulate error in long computations