Port Range
Calculate the number of ports and validate ranges within TCP/UDP port allocations.
About Port Range
The 16-bit TCP/UDP port number space (0-65535) is divided by IANA into three categories: well-known ports (0-1023), reserved for system/standard services like HTTP (80) and SSH (22) and traditionally requiring elevated privileges to bind; registered ports (1024-49151), which applications and services can register with IANA for specific use (e.g. many database and application server defaults); and dynamic/private ports (49152-65535), used for ephemeral, temporary connections such as a client's outbound source port for a new connection. A port range can span one or more of these categories depending on where its start and end fall.
Formula
Total ports in range
total_ports = end_port − start_port + 1
Worked example
With the default values below, Port Range returns Total Ports in Range of 101. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Start Portaccepts 0–65,535
- 8,000
- End Portaccepts 0–65,535
- 8,100
Results
- Total Ports in Range
- 101
- Categories Spanned
- Registered (1024-49151)
- Well-Known Ports (0-1023)
- 0
- Registered Ports (1024-49151)
- 101
- Dynamic/Private Ports (49152-65535)
- 0
Step by step
- 1Values used
- 2Total ports in range
- 3Total Ports in Range= 101
- 4Categories Spanned= Registered (1024-49151)
- 5Well-Known Ports (0-1023)= 0
- 6Registered Ports (1024-49151)= 101
- 7Dynamic/Private Ports (49152-65535)= 0
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why do well-known ports traditionally require elevated privileges?
On Unix-like systems, binding to ports below 1024 has historically required root/administrator privileges, a security convention meant to ensure that only trusted, system-level processes can claim these reserved 'standard service' ports (e.g. so a regular user process can't impersonate a web server on port 80).
What are dynamic/private ports typically used for?
Operating systems automatically assign a port from the dynamic/private range (49152-65535, sometimes called ephemeral ports) as the temporary source port for outbound client connections — for example, when your browser connects to a web server, it uses a random port from this range as its own source port for that connection.
Can an application use a registered port without formally registering it with IANA?
Yes — while IANA maintains an official registry mapping many registered ports to specific well-known applications (e.g. 3306 for MySQL, 5432 for PostgreSQL) as a convention to avoid conflicts, nothing technically prevents any application from using an unregistered port in that range; it's a convention, not an enforced restriction.
Why might a firewall rule span multiple port categories?
Some legacy applications or custom services intentionally use wide port ranges that straddle category boundaries (e.g. an FTP passive-mode range spanning into both registered and dynamic ports), which is why understanding what categories a given range covers matters for both security review and troubleshooting connectivity issues.