Skip to content

Instantly share code, notes, and snippets.

@f-steff

f-steff/excel formulas.md

Last active November 25, 2025 13:12
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save f-steff/d2ef30bed5328f0e417d635d3b46e256 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save f-steff/d2ef30bed5328f0e417d635d3b46e256 to your computer and use it in GitHub Desktop.
Download ZIP
Excel formulas to calculate IP values such as Netmask, IP range start, IP range end, Broadcast IP, Number of hosts.
Raw
excel formulas.md

Excel formulas to calculate IP values - Works in Excel and Google Sheet.

Updated 2023-12-11: Hosts calculation updated to support CIDR or 31 and 32.

Prerequisites:

  • A1 contains an IP address, such as 10.0.0.2
  • B1 contains the number of bits in the netmask (CIDR) such as 24

The below formulas then go into C1, D1 etc. to perform the various calculations. Some calculations depends on other calculations.

A Google Sheet with all the formulas can be accessed and copied here: https://docs.google.com/spreadsheets/d/1G-vStX0DRB7tq-wvbALnL4HeXYXXOkjh_GriTN-b6-o (Also updated 2023-12-11)

Note, the formulas below are written with the comma spreadsheet notation used in most countries globally. You may need to change the notation to semicolon notation, which is primearly used in the U.S. E.g. =ROUND(PI(),3) and =ROUND(PI();3) are identical but uses different formula notation.

Huge thanks to @6d6163 and @Baribf for pointing out a mistake when used in Excel (The instance_num in Substitute() must not be zero!) and for spotting that the StartIP in a range must be one higher than the range number. They also spotted a copy/paste error mixing up A1 and C1. Their work is what triggred the march 16. 2023 update of these formulas.

C1: Calculate netmask

=BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),1,8))
&"."&
BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),9,8))
&"."&
BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),17,8))
&"."&
BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),25,8))

D1: Calculate start of IP range

=BITAND( 
  (LEFT(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),1,8)))
)
&"."&
BITAND(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),9,8)))
)
&"."&
BITAND(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-1)),
  (BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),17,8)))
)
&"."&
BITAND(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))+1,FIND(CHAR(160),SUBSTITUTE(A1&".",".",CHAR(160),4))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-1)), 
  (BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),25,8)))
)+1

E1: Calculate end of IP range

=BITOR(
  (LEFT(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),1,8)))
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),9,8)) )
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),17,8)))
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))+1,FIND(CHAR(160),SUBSTITUTE(A1&".",".",CHAR(160),4))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),25,8)))
)-1

F1: Calculate Broadcast IP

=BITOR(
  (LEFT(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),1,8)))
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),1))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),9,8)))
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))+1,FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),2))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),17,8)))
)
&"."&
BITOR(
  (MID(A1, FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))+1,FIND(CHAR(160),SUBSTITUTE(A1&".",".",CHAR(160),4))-FIND(CHAR(160),SUBSTITUTE(A1,".",CHAR(160),3))-1)),
  (255-BIN2DEC(MID(REPT("1",B1)&REPT("0",32-B1),25,8)))
)

G1: Calculate number of hosts

Updated the method of calculating the number of hosts, to peoperly calculate the number of hosts when CIDR is set to 31 (peer-to-peer network) and 32 which is a single IP.

=switch(B1, 31,2, 32,1, (2^(32-B1)-2))

Example

For an IP setup such as 10.100.10.20/20 the following values will be calculated:

  • Netmask: 255.255.240.0
  • Start IP: 10.100.0.1
  • End IP: 10.100.15.254
  • Broadcast IP: 10.100.15.255
  • Number of hosts: 4094
@iainhu
Copy link

iainhu commented Nov 25, 2025

Another observation is after download of your sample spreadsheet in Excel .xlsx format, the formulae use @bitand and @bitor which Excel (365) reports as a #NAME! error. Allowing Excel to remove the ampersand to simply 'BITAND'/'BITOR' resolves the issue.

Looking at your formulae in Sheets, I see no @ and so I can only presume this is an artifact introduced by the Sheets save to .xlsx format, but it may trip some people up. It's not a fault on the same sheet, it appears to be an 'error' in the Shees save function. To resolve simply place your cursor in each field and hit enter. Excel will then suggest it updates the formula and all will work afterwards 🙂

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment