Round any number to a whole number, a number of decimal places, a fraction, or significant figures. Choose from nine rounding modes — including the everyday "half up" and the statistician's "half even" — to control exactly how ties and negatives are handled.
The rounding calculator reduces the precision of a number to make it shorter, simpler, and easier to work with. Enter a value and choose how you want it rounded — to a whole number, to a set number of decimal places, to the nearest fraction, or to a chosen number of significant figures — and the calculator returns the rounded result. For full control, it also offers nine different rounding modes that decide exactly how "halfway" values and negative numbers are handled. Whether you are tidying up a measurement, preparing a figure for a report, or studying how rounding works, this tool does it precisely and instantly.
This page explains what rounding is, the different ways you can round a number, every rounding mode and what it does, worked examples you can reproduce, and answers to the questions people ask most. By the end you will know not just how to round, but which method and mode to choose for any situation.
Rounding means replacing a number with a nearby value that is simpler or has fewer digits. Real-world numbers are often more precise than we need — a measurement of 3324.238576 is unwieldy, and for most purposes 3324, 3324.24, or even 3300 conveys the important information without the clutter. Rounding trades a small amount of accuracy for a large gain in readability and convenience. The key decision in any rounding is the precision: how many digits, decimal places, or what unit you want to keep. Once that is fixed, the number is replaced by the nearest "allowed" value at that precision — and a rounding mode settles what to do when the original sits exactly halfway between two allowed values.
This calculator supports four different targets for rounding, because "round it" can mean different things:
A rounding mode decides how to handle a value that falls exactly between two candidates, and how to treat negative numbers. All examples below round to the nearest integer.
Take the number 3324.238576. Rounded to two decimal places with the default half-up mode, the result is 3324.24, because the third decimal (8) is 5 or more, so the hundredths digit rounds up from 3 to 4. Rounded to the nearest whole number it becomes 3324; rounded to the nearest hundred (digits to round = 2) it becomes 3300; and rounded to three significant figures it becomes 3320. Each of these keeps a different amount of the original information while making the number easier to read. The calculator's default is exactly this example rounded to 2 decimals, so you can press Calculate to see 3324.24 and then change the precision or mode.
Rounding modes matter most for negative numbers and exact halves. Consider −123.5 rounded to a whole number. With half up (the default) it becomes −124, because ties round away from zero. With half down it would be −123; with half even it becomes −124 (because −124 is even); with ceil it becomes −123 (toward +∞); and with floor it becomes −124 (toward −∞). The value 456.5 rounds to 457 under half up, half even, and half ceil, but to 456 under half down and half floor. Trying these on the calculator is the quickest way to build intuition for how each mode behaves.
Rounding to a fixed number of decimal places is the everyday kind of rounding you meet with money, measurements, and reports. To round to n decimal places, you look at the digit in the (n+1)th place: if it is 5 or more (under half up), the nth digit increases by one; otherwise it stays the same, and all later digits are dropped. Rounding 3.14159 to two decimals gives 3.14, to three gives 3.142, and to four gives 3.1416. Money is almost always rounded to two decimal places (cents), and choosing the right number of decimals is a balance between precision and readability. The calculator lets you pick any number of decimal places and any mode, so you can match the convention your task requires.
Significant figures count the meaningful digits in a number, starting from the first non-zero digit. Rounding to significant figures is the standard way scientists and engineers express the precision of a measurement, because it scales with the size of the number rather than fixing the decimal position. The number 3324.238576 rounded to two significant figures is 3300, to three is 3320, and to four is 3324. Note how trailing zeros act as placeholders: 3300 has two significant figures here even though it has four digits. Rounding to significant figures is especially useful for very large or very small numbers, where a fixed number of decimal places would be clumsy, and it is essential for reporting experimental results honestly — you should never present more significant figures than your measurement actually supports.
Ordinary half-up rounding has a subtle bias: because every exact half rounds up, a long list of rounded numbers tends to drift slightly higher than the true total. Banker's rounding, or "round half to even," fixes this by sending ties to the nearest even number instead — 2.5 rounds to 2, but 3.5 rounds to 4. Over many values, roughly half the ties go up and half go down, so the rounding errors cancel out and averages and sums stay closer to the truth. This is why banker's rounding is the default in many financial systems, spreadsheets, and programming languages, and why it is written into standards like IEEE 754 for floating-point arithmetic. If you are rounding many numbers that will be summed or averaged — especially money — half even is often the fairer choice.
Rounding is everywhere. Shops round prices to the nearest cent, and some countries round cash totals to the nearest five cents because they have retired small coins. Scientists round measurements to significant figures to reflect their instruments' precision. Engineers round dimensions to practical tolerances. Statisticians round results for reports while using banker's rounding to avoid bias. Software rounds constantly, and the choice of mode can cause subtle bugs if it does not match expectations. Even everyday estimation is a form of rounding — when you say a journey is "about 300 miles," you have rounded to the nearest hundred. Understanding the different targets and modes helps you round appropriately for each situation rather than reaching for the same method every time.
Not everything is measured in tenths and hundredths. Carpenters and machinists work in halves, quarters, eighths, and sixteenths of an inch; musicians divide beats into fractions; and recipes call for a third or a quarter of a cup. Rounding to a fraction snaps a value to the nearest multiple of the fraction you choose. To round to the nearest quarter, for instance, the calculator finds the closest multiple of 0.25 — so 3.3 becomes 3.25 and 3.4 becomes 3.5. You can enter the fraction directly (such as 1/4 or 1/16) or as a decimal (0.25), and the same rounding modes apply to decide how exact halfway values are handled. This makes the tool useful well beyond decimal rounding, matching the way measurements are actually expressed in workshops, kitchens, and sheet music.
Computers store most decimal numbers in binary, and many everyday decimals — like 0.1 or 2.675 — cannot be represented exactly. This is why naive rounding in code sometimes produces surprises, such as 2.675 rounding to 2.67 instead of 2.68, because the stored value is really 2.6749999…. A well-built rounding tool cleans up this tiny representational error before deciding which way a halfway value should go, so that exact halves behave the way people expect. It is also why banker's rounding is written into the IEEE 754 floating-point standard that virtually all computers follow: by sending ties to the nearest even digit, it keeps rounding errors from accumulating in the same direction across millions of operations. When you round here, the calculator accounts for this behavior so the results match hand calculation rather than the raw quirks of binary storage.
Decide the precision (decimal places, a whole-number place, a fraction, or significant figures), then replace the number with the nearest value at that precision. If it is exactly halfway, a rounding mode such as "half up" decides the direction.
The default is "half up": round to the nearest value, and if the number is exactly halfway, round away from zero. This is the rounding taught in most schools.
Banker's rounding, or "half even," sends exact halves to the nearest even number (2.5 → 2, 3.5 → 4). It reduces bias when many rounded numbers are summed or averaged.
Count meaningful digits from the first non-zero digit and keep only that many, rounding the rest. For example, 3324.24 to three significant figures is 3320.
"Up" always moves away from zero; "ceil" always moves toward positive infinity; "floor" always moves toward negative infinity. They differ only for negative numbers.
Choose "Whole number" and set "digits to round" to 1 for the nearest ten, 2 for the nearest hundred, or 3 for the nearest thousand.
This Rounding Calculator is provided for general educational purposes. It applies standard rounding rules and modes to the number and precision you enter. Because computers store decimals in binary, extremely long or extreme-magnitude inputs may show tiny representational differences.