Bit Shift Calculator
Calculate left and right bit shifts - clearly distinguishes arithmetic (sign-preserving) from logical (zero-fill) right shift.
Enter a number and a shift amount - this tool calculates left shift, arithmetic right shift, and logical right shift, showing how they differ.
Arithmetic right shift preserves the sign bit (fills with 1s for negative numbers) - logical/unsigned right shift always fills with 0s, treating the value as unsigned. Shift counts are limited to 0-31 since JavaScript's bitwise operators work on 32-bit integers.
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View all 19Arithmetic right shift preserves the sign bit (useful for signed integers); logical right shift always fills with zeros (used for unsigned values) - the difference only matters for negative numbers.
Arithmetic vs. Logical Right Shift
A left shift (<<) always fills vacated bits with zero. A right shift has two variants: arithmetic (>>) fills vacated bits with copies of the sign bit (preserving whether the number is negative), while logical (>>>) always fills with zeros regardless of sign.
How to Use It
- Enter an integer and a shift amount.
- View the left shift, arithmetic right shift, and logical right shift results side by side, with binary representations.
Limitations
Uses JavaScript's native 32-bit shift operators, matching standard integer shift behavior in most languages - shift amounts are taken modulo 32, and invalid (non-integer) shift counts are rejected rather than silently truncated.
Examples
| Expression | Binary | Result |
|---|---|---|
5 << 2 | 101 → 10100 | 20 (5 × 4) |
40 >> 3 | 101000 → 101 | 5 (40 ÷ 8) |
-16 >> 2 | sign bit copied | -4 |
-16 >>> 2 | zeros shifted in | 1073741820 |
Shifting left by n multiplies by 2n; an arithmetic right shift divides by 2n, rounding towards negative infinity.
Where Bit Shifts Are Used
- Flags:
1 << 3creates a mask with only bit 3 set, e.g. for permission or feature flags. - Packing values: combining RGB channels into one integer with
(r << 16) | (g << 8) | b. - Fast arithmetic in performance-critical or embedded code.
- Hash functions and checksums, which shift and mix bits.
Watch Out For
- Shifting a 32-bit value by 32 does not give 0 in JavaScript - the shift amount wraps to 0.
- Left-shifting into the sign bit turns a large positive number negative.
- Different languages define right shifts on negative numbers differently; check yours.
Combine shifted values with the Bitwise Calculator, and inspect them with Decimal to Binary.
Frequently Asked Questions
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