user@netcalc ~/calc $
ipv4_calculator
Calculate network, broadcast, mask, hosts, class and binary for any IPv4 address
ip:
mask:
✓ stdout — ipv4_calculator
NetCalc · project information
MTU & Tunnel Overhead Reference
Quick MTU and encapsulation overhead reference for PPPoE, GRE, WireGuard and variable IPsec stacks.
Enter runs the calculation · Shift+Enter inserts a new line
user@netcalc ~/calc $
ipv6_calculator
Calculate network info for IPv6 addresses in CIDR notation
ipv6:
pfx:
✓ stdout — ipv6_calculator
user@netcalc ~/calc $
vlsm_calculator
Variable Length Subnet Mask — assigns optimal blocks for each network segment
net:
pfx:
// Subnets required
name:
hosts:
name:
hosts:
name:
hosts:
✓ stdout — vlsm_calculator
| # | Name | Hosts Req | Hosts Avail | Prefix | Network | First Host | Last Host | Broadcast | Mask |
|---|
user@netcalc ~/calc $
usable_ip_range
Shows the exact usable host range for a given network
ip:
mask:
✓ stdout — usable_ip_range
user@netcalc ~/calc $
binary_ip_calc
Convert IP addresses to binary and vice versa, with per-octet visualization
dec:
bin:
✓ stdout — binary_ip_calc
user@netcalc ~/network $
cidr_converter
Convert between CIDR, decimal mask and wildcard. Includes full /1–/32 reference table.
in:
✓ stdout — cidr_converter
📋 CIDR Reference Table
| CIDR | Subnet Mask | Wildcard | Hosts | /24 subnets | Block |
|---|
user@netcalc ~/network $
wildcard_mask_calc
Calculate the wildcard (inverse) mask for Cisco ACLs, OSPF and firewall rules
mask:
✓ stdout — wildcard_mask_calc
user@netcalc ~/network $
supernet_calculator
Find the minimum supernet containing all specified networks (route summarization)
nets:
✓ stdout — supernet_calculator
user@netcalc ~/network $
subnet_splitter
Split a network into equal subnets by specifying a new prefix
net:
mask:
new:
✓ stdout — subnet_splitter
| # | Network | First Host | Last Host | Broadcast | Hosts | Mask |
|---|
user@netcalc ~/network $
range_to_cidr
Convert an IP range (start–end) to the minimum set of CIDR blocks
start:
end:
✓ stdout — range_to_cidr
| # | CIDR Block | Network | Broadcast | Hosts |
|---|
user@netcalc ~/network $
ip_to_integer
Convert IPv4/IPv6 addresses to integer and vice versa
ip:
int:
✓ stdout — ip_to_integer
user@netcalc ~/network $
ipv6_normalize
Expand and compress IPv6 addresses — normalize any valid format
ipv6:
✓ stdout — ipv6_normalize
user@netcalc ~/network $
hex_ip_converter
Convert between hexadecimal and IP address — useful for Windows route tables and Cisco logs
ip:
0x:
✓ stdout — hex_ip_converter
user@netcalc ~/network $
vlan_calculator
802.1Q VLAN info: tag encoding, PCP, DEI, VID, range and compatibility
vlan:
pcp:
dei:
✓ stdout — vlan_calculator
user@netcalc ~/dns $
reverse_dns_generator
Generate the PTR in-addr.arpa zone for an IPv4 network
net:
pfx:
dom:
✓ stdout — reverse_dns_generator
user@netcalc ~/dns $
ipv6_ptr_generator
Generate the PTR ip6.arpa record for an IPv6 address
ipv6:
host:
✓ stdout — ipv6_ptr_generator
user@netcalc ~/dns $
ip_geolocation
Locate a public IP or resolve a domain and geolocate its public address
Domains are resolved through DNS first; geolocation is based on the resulting public IP.
geo:
✓ stdout — ip_geolocation
user@netcalc ~/dns $
ip_address_planner
Interactive IP address space planner — click cells to edit, export to CSV
📋 IP Address Plan
| # | Name | Network | Mask/CIDR | Gateway | VLAN | Location | Notes |
|---|
user@netcalc ~/legal $
Privacy
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Calculations
Calculations are sent through this site's same-origin Worker proxy to the private calculation service.
Performance metrics
LCP, CLS and INP may be stored as aggregate performance measurements by tool and language. Calculation inputs and persistent user identifiers are not included.
GeoIP
Only GeoIP lookups are processed by an external provider. The requested IP address is sent for that lookup.
Issue reports via Telegram
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Cookies and advertising
Advertising is controlled by the production configuration. When Google AdSense is enabled, consent is handled through a certified CMP before personalized advertising is used where required.
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Use the button below to clear calculation history. To remove every local preference, clear this site's data in your browser settings.
This page provides operational information; it is not a legal-compliance certification.
Quick MTU and encapsulation matrix
Values are engineering references starting from a 1500-byte IP MTU. Real implementations may add options or extra layers: always confirm the actual stack and validate the path with PMTUD.
Typical overhead
| Encapsulation | Overhead (bytes) | Inner MTU from 1500 | Notes |
|---|---|---|---|
| Ethernet L3 | 0 | 1500 | Common IP MTU baseline |
| PPPoE | 8 | 1492 | PPPoE + PPP header |
| GRE / IPv4 | 24 minimum | 1476 | 20-byte outer IPv4 + 4-byte basic GRE |
| WireGuard / IPv4 | 60 | 1440 | IPv4 + UDP + WireGuard overhead |
| WireGuard / IPv6 | 80 | 1420 | IPv6 + UDP + WireGuard overhead |
| IPsec ESP | variable | — | Depends on mode, cipher, authentication, padding and NAT-T |
Useful formulas
inner_mtu = underlay_mtu - encapsulation_overhead tcp_mss_ipv4 ≈ inner_mtu - 40 tcp_mss_ipv6 ≈ inner_mtu - 60
MSS clamping only affects TCP. UDP, QUIC and other protocols still depend on a correct path MTU and on required ICMP messages not being blocked.
Primary sources
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