Memory Address Tool

Pointer Arithmetic Calculator

Calculate pointer addition or subtraction using a base memory address, element size, and signed element offset. Get the resulting address, exact byte displacement, hexadecimal form, and calculation breakdown.

Pointer + n Element-size scaling Decimal & hex

Calculate Pointer Address Movement

Base address Nonnegative integer

Address format

Element size Bytes

Element offset Signed integer: +5 or -3

Formula: new pointer = base address + (element offset × element size).

Result Address 0x1014 Hexadecimal

Result Address 4116 Decimal

Byte Displacement 20 bytes

Element Offset +5

Element Size 4 bytes

Direction Forward

Pointer arithmetic

0x1000 + (5 × 4 bytes) = 0x1014

Pointer Math

What Is Pointer Arithmetic?

Pointer arithmetic is address calculation in which an integer offset is scaled by the size of the pointed-to element rather than treated directly as a raw byte count.

In C and C++, adding 1 to a pointer does not normally increase the address by one byte. Instead, it advances to the next object of the pointer’s pointed-to type.

If an int occupies 4 bytes, adding 1 to an int* advances the address by 4 bytes. Adding 5 advances it by 20 bytes.

Pointer addition newAddress = baseAddress + (elementOffset × elementSize)

How to Use

How to Use the Pointer Arithmetic Calculator

Enter the base pointer address Use a decimal address such as 4096 or a hexadecimal address such as 0x1000.

Enter the element size Specify the number of bytes occupied by one pointed-to element.

Enter the element offset Use a positive value to move forward or a negative value to move backward.

Calculate the result The calculator scales the element offset by the element size and applies the resulting byte displacement to the base address.

Worked Example

Pointer Arithmetic Example: 0x1000 + 5 int Elements

Suppose an int* points to address 0x1000 and one integer occupies 4 bytes. Advancing by five elements means moving 20 bytes forward.

Example calculation

Base address = 0x1000 Element size = 4 bytes Element offset = +5 Byte displacement: 5 × 4 = 20 bytes 20 decimal = 0x14 New address: 0x1000 + 0x14 = 0x1014 Result = 0x1014

Subtraction

Pointer Subtraction by an Element Offset

A negative element offset moves the pointer backward. The element count is still multiplied by the size of one element before being applied to the address.

Move backward by three 8-byte elements

Base address = 0x2000 Element size = 8 bytes Element offset = -3 Byte displacement: -3 × 8 = -24 bytes 24 decimal = 0x18 New address: 0x2000 – 0x18 = 0x1FE8

Element Scaling

Why Pointer Arithmetic Depends on Element Size

Pointer arithmetic is designed to move between elements of a particular type. This means the same element offset can produce different byte movements depending on the pointed-to object size.

Element Size	Offset	Byte Movement	Meaning
1 byte	+5	+5 bytes	Five 1-byte elements
2 bytes	+5	+10 bytes	Five 2-byte elements
4 bytes	+5	+20 bytes	Five 4-byte elements
8 bytes	+5	+40 bytes	Five 8-byte elements
16 bytes	+5	+80 bytes	Five 16-byte elements

Array Indexing

Pointer Arithmetic and Array Indexing

Array indexing is closely related to pointer arithmetic. Conceptually, accessing element i of a contiguous array corresponds to an address based on the array’s starting address plus i times the size of one element.

Element address address(i) = base + i × elementSize

If an array begins at address 1000 and each element is 8 bytes, element 7 begins 56 bytes after the base, at address 1056.

The arithmetic result does not prove that a resulting address is valid to dereference. Actual language rules and object bounds still matter.

Byte Offset

Element Offset vs Byte Offset

An element offset counts objects. A byte offset counts raw bytes. Pointer arithmetic converts the element offset into a byte offset using the size of one object.

Conversion byteOffset = elementOffset × elementSize

For an element size of 4 bytes, pointer offset +10 corresponds to +40 bytes. For an element size of 8 bytes, the same +10 corresponds to +80 bytes.

Hexadecimal

Pointer Arithmetic with Hexadecimal Addresses

Memory addresses are frequently represented in hexadecimal because each hexadecimal digit maps neatly to four binary bits.

The calculator accepts hexadecimal base addresses directly, including an optional 0x prefix, and shows the resulting pointer in both hexadecimal and decimal.

Hexadecimal address movement

Base = 0x4000 Element size = 16 bytes Offset = +3 3 × 16 = 48 decimal 48 decimal = 0x30 0x4000 + 0x30 = 0x4030

Reference

Pointer Arithmetic Examples

Base Address	Element Size	Offset	Byte Movement	Result
0x1000	4	+1	+4	0x1004
0x1000	4	+5	+20	0x1014
0x1000	8	+5	+40	0x1028
0x2000	8	-3	-24	0x1FE8
4096	4	+10	+40	4136
0x100	1	+16	+16	0x110

Pointer Difference

How Pointer Difference Relates to Element Size

When two compatible pointers refer into the same array object, the conceptual element distance between them corresponds to the byte address difference divided by the size of one element.

Element distance elementDifference = addressDifference / elementSize

For example, if two addresses differ by 40 bytes and each element is 8 bytes, they are five element positions apart.

This calculator focuses on pointer plus or minus an integer offset rather than validating language-level pointer subtraction between arbitrary objects.

Type Examples

Pointer Arithmetic for Different Element Sizes

Byte / char-like data

With 1-byte elements, an element offset and byte offset have the same numeric magnitude.

16-bit values

For 2-byte elements, every pointer step changes the address by two bytes.

32-bit values

A common 4-byte element size produces four bytes of address movement per step.

64-bit values

An 8-byte element moves the address by eight bytes for every element offset.

Struct pointers

A pointer to a structure advances by the complete size of one structure object.

Custom records

Use the actual object size when modeling pointer movement across custom elements.

Struct Pointers

Pointer Arithmetic with Structures

When a pointer refers to a structure type, one pointer step advances by the complete structure size, including any padding that contributes to sizeof(struct).

Suppose a structure occupies 24 bytes. If a pointer to that structure begins at address 0x1000, then adding 3 moves the pointer by 72 bytes.

Struct pointer example

Base = 0x1000 sizeof(struct) = 24 bytes Offset = +3 Byte movement: 3 × 24 = 72 72 decimal = 0x48 New address: 0x1000 + 0x48 = 0x1048

Validity

Address Calculation Does Not Guarantee a Valid Pointer

This calculator performs numerical address arithmetic. Programming languages impose additional rules on whether a pointer operation itself is valid and whether the resulting pointer may be dereferenced.

In C and C++, for example, pointer arithmetic is generally meaningful within an array object and one position past its end. Arbitrary numerical addresses should not automatically be treated as valid objects.

Use this calculator for arithmetic, memory-layout reasoning, debugging, reverse engineering, and educational calculations—not as proof that a particular memory access is legal or safe.

Large Addresses

Exact Arithmetic for Large Pointer Values

JavaScript’s ordinary Number type cannot represent every large integer exactly. Pointer and address calculations are integer operations, so losing precision could produce incorrect results at large magnitudes.

This calculator uses BigInt for the base address, element size, signed element offset, displacement, and resulting address.

This avoids ordinary floating-point integer precision loss and also avoids the 32-bit truncation associated with standard JavaScript Number bitwise operators.

Common Mistakes

Common Pointer Arithmetic Mistakes

Treating the offset as bytes

In typed pointer arithmetic, the integer offset is scaled by the pointed-to element size.

Forgetting structure padding

Pointer arithmetic on a structure pointer uses the complete structure size, not merely the sum of visible member data bytes.

Using the wrong element size

If the object is 8 bytes but you enter 4, every resulting address will be calculated using the wrong stride.

Ignoring negative offsets

Pointer subtraction by an integer can be represented by a negative element offset, which produces a negative byte displacement.

Assuming any calculated address can be dereferenced

Numerical arithmetic and valid program pointer semantics are not the same thing.

FAQ

Pointer Arithmetic Calculator FAQs

Pointer arithmetic changes a pointer address by an integer number of elements. The element count is multiplied by the size of the pointed-to type.

Multiply 5 by the element size and add that byte displacement to the base address.

It moves the numerical address forward by 4 bytes.

Numerically, it moves backward by three elements, or three times the element size in bytes.

Yes. Choose Hexadecimal and enter an address such as 0x1000.

Element offset counts objects. Byte offset is the actual address movement: element offset multiplied by element size.

Each pointer step moves by the complete sizeof the structure, including padding included in that structure size.

Yes. A negative offset produces backward numerical address movement.

This calculator rejects calculations that would produce a negative numerical address because ordinary memory addresses are modeled here as nonnegative integers.

Not exactly. The address ultimately uses integer addition, but the pointer offset is first scaled by the element size.

No. The tool performs address arithmetic only. Object bounds, lifetime, permissions, language rules, and actual memory mapping determine validity.

Yes. It uses JavaScript BigInt for exact integer address calculations.