Memory Range Utility

Address Range Calculator

Calculate a memory range from start and end addresses, or enter a starting address and byte size to find the final inclusive address. Get exact hexadecimal and decimal boundaries with range size.

Start ↔ End Start + Size Exact BigInt math

Calculate Memory Address Range

Calculation

Address format

Start address First address

End address Inclusive last address

Inclusive size = end address − start address + 1.

Address Range 0x1000 – 0x10FF Inclusive start through end

Inclusive Range Size 256 bytes Number of addressable byte positions

Start Address 0x1000

End Address 0x10FF

Exclusive Span 255 bytes

Size in Hex 0x100

Calculation

0x10FF − 0x1000 + 1 = 0x100 = 256 bytes

Memory Boundaries

What Is an Address Range?

An address range describes a continuous interval of memory locations from a starting address to an ending address. Address ranges are widely used when working with buffers, memory maps, device registers, file mappings, firmware, operating systems, and low-level software.

For an inclusive byte-address range, both the first and last addresses belong to the range. That means the number of addressable byte positions is one greater than the simple difference between the endpoints.

Inclusive range size size = endAddress – startAddress + 1

Two Modes

Calculate a Range from End Address or Byte Size

The Address Range Calculator supports the two common directions of memory range calculation.

Start + End → Range Size Enter the first and last inclusive addresses. The calculator determines the total byte range and the numerical span between the endpoints.

Start + Size → End Address Enter the first address and the number of bytes in the range. The calculator determines the final inclusive address.

Worked Example

Address Range from 0x1000 to 0x10FF

Consider an inclusive memory range beginning at 0x1000 and ending at 0x10FF.

Inclusive address range calculation

Start = 0x1000 End = 0x10FF Exclusive span: 0x10FF – 0x1000 = 0xFF 0xFF = 255 decimal Inclusive size: 255 + 1 = 256 bytes Therefore: Range = 0x1000 through 0x10FF Size = 256 bytes = 0x100

Start + Size

Find an End Address from Start Address and Size

When you already know the number of bytes in a memory block, the last inclusive address is found by adding the size minus one to the starting address.

Inclusive end address endAddress = startAddress + size – 1

256-byte range starting at 0x8000

Start = 0x8000 Size = 256 bytes = 0x100 End: 0x8000 + 0x100 – 1 = 0x80FF Range: 0x8000 through 0x80FF

Off-by-One

Why Inclusive Address Ranges Add One

A common address-range mistake is to subtract the start from the end and assume the difference is the number of bytes. That calculation gives the distance between the two addresses, not the number of byte positions when both endpoints are included.

For example, the range from address 100 to address 100 contains one addressable byte position, even though 100 - 100 = 0.

Start	End	End − Start	Inclusive Size
0	0	0	1 byte
0	1	1	2 bytes
100	103	3	4 bytes
0x1000	0x10FF	0xFF	0x100 = 256 bytes

Inclusive vs Exclusive

Inclusive End Address vs Exclusive End Address

This calculator treats the displayed end address as the last included byte address. This convention is common in memory-map documentation where a region may be written as 0x1000–0x1FFF.

Some programming interfaces instead represent ranges using a start address and an exclusive end address. With that convention, the exclusive endpoint is the address immediately after the range.

Same 256-byte block, two conventions

Start address: 0x1000 Size: 256 bytes Inclusive last address: 0x10FF Exclusive end address: 0x1100 Inclusive notation: 0x1000 – 0x10FF Half-open notation: [0x1000, 0x1100)

The calculator’s main end-address result is inclusive. This avoids ambiguity when calculating the exact last byte contained in a memory region.

Hexadecimal

Calculating Hexadecimal Address Ranges

Hexadecimal is the standard visual format for many memory addresses because it represents binary values compactly. One hexadecimal digit corresponds to four binary bits.

Common power-of-two memory regions also produce easy-to-recognize hexadecimal boundaries. A 4 KiB block beginning at 0x4000, for example, has 4096 bytes or 0x1000 bytes.

4 KiB hexadecimal range

Start = 0x4000 Size = 4096 bytes = 0x1000 bytes Last address: 0x4000 + 0x1000 – 1 = 0x4FFF Range: 0x4000 – 0x4FFF

Reference

Address Range Examples

Start	End	Inclusive Size	Size Hex	Exclusive End
0x1000	0x10FF	256 bytes	0x100	0x1100
0x1000	0x1FFF	4096 bytes	0x1000	0x2000
0x8000	0x80FF	256 bytes	0x100	0x8100
0x0000	0xFFFF	65,536 bytes	0x10000	0x10000
4096	5119	1024 bytes	0x400	5120

Memory Maps

Address Ranges in Memory Maps

Memory maps divide an address space into regions assigned to RAM, ROM, flash memory, peripherals, device registers, shared buffers, or reserved areas. Each region is commonly described using a starting address and an ending address or a starting address and length.

The calculator can convert between these two representations. This is useful when documentation supplies boundaries but software expects a byte length, or when a memory allocator provides a base and size but you need the final address.

Buffers

Calculating Buffer Address Boundaries

Suppose a buffer starts at address 0x200000 and contains 1024 bytes. The last valid byte is not at 0x200000 + 1024. That value points immediately after the buffer.

1024-byte buffer

Start = 0x200000 Size = 1024 = 0x400 Exclusive end: 0x200000 + 0x400 = 0x200400 Inclusive last byte: 0x200400 – 1 = 0x2003FF Valid inclusive range: 0x200000 – 0x2003FF

Range Size

Bytes, KiB, MiB, and Address Range Size

Address arithmetic is performed in integer byte positions. Memory sizes are often also described using binary units such as KiB and MiB.

Unit	Bytes	Hexadecimal Size
1 KiB	1,024	0x400
4 KiB	4,096	0x1000
64 KiB	65,536	0x10000
1 MiB	1,048,576	0x100000
16 MiB	16,777,216	0x1000000

Applications

Where Address Range Calculations Are Useful

Memory Mapping

Calculate the exact boundaries and sizes of mapped memory regions.

Embedded Systems

Work with flash, RAM, peripheral, and memory-mapped register regions.

Buffer Analysis

Find the first and final byte addresses of buffers with known sizes.

Debugging

Check whether addresses fall near the expected boundaries of an object or memory block.

Binary Analysis

Translate start/end boundaries into exact region lengths while inspecting binary layouts.

Operating Systems

Reason about pages, virtual address regions, segments, and memory allocation boundaries.

Validation

Valid and Invalid Address Ranges

In Start + End mode, the end address must be greater than or equal to the start address for a forward inclusive range.

An end address below the start would describe reversed boundaries rather than the normal ascending range used by this calculator.

In Start + Size mode, the byte size must be at least one because an inclusive non-empty range needs at least one addressable position.

This calculator performs mathematical address-range calculations. It does not verify whether the resulting addresses exist in a real process, physical memory map, or virtual address space.

Large Addresses

Exact Address Range Arithmetic with BigInt

Memory addresses and range lengths are integers, so exact arithmetic is important. JavaScript’s ordinary Number type cannot represent every large integer exactly once values exceed its safe integer precision.

This calculator uses BigInt for addresses, sizes, spans, and range boundaries. It therefore avoids floating-point rounding during the calculation.

Hexadecimal results are generated directly from the exact integer values, making the tool useful for both ordinary machine-sized addresses and much larger theoretical integer ranges.

Common Mistakes

Common Address Range Calculation Mistakes

Forgetting the inclusive +1

For inclusive endpoints, end - start is the span, while end - start + 1 is the number of byte addresses.

Adding the full size to find the last byte

start + size gives the exclusive endpoint. The final included byte is start + size - 1.

Mixing decimal and hexadecimal

Select the correct address format before entering the values. A hexadecimal value such as 1000 does not represent the same integer as decimal 1000.

Using zero as a range size

A non-empty inclusive range requires at least one byte. A size of zero has no valid inclusive last byte under this calculator’s range convention.

Assuming calculated addresses are mapped

Numerical validity does not prove that a real system has usable memory at those addresses.

FAQ

Address Range Calculator FAQs

For an inclusive range, subtract the start address from the end address and add one: size = end – start + 1.

The inclusive range contains 0x100 bytes, which is 256 decimal bytes.

Use end = start + size – 1 when the end address is inclusive.

The starting address already represents the first byte. Adding the full size points one byte beyond the range, so subtract one to obtain the final included address.

An inclusive end is the last address inside the range. An exclusive end is the first address immediately after the range.

Yes. Select Hexadecimal and enter values such as 0x1000 and 0x1FFF.

The inclusive range contains exactly one byte address, so its size is one.

Not for the ascending inclusive range convention used here. The calculator reports an error if the end address is below the start.

It is end – start, which measures the numerical distance between the first and last addresses. The inclusive size is one greater.

4 KiB contains 4096 bytes, equal to hexadecimal 0x1000 byte positions.

No. It calculates numerical address boundaries only and does not inspect a computer’s physical or virtual memory map.

Yes. It uses JavaScript BigInt so integer addresses and range sizes are calculated exactly without ordinary floating-point precision loss.