Updated: 28 September 2026 · Applies to: GNU bc 1.07 on AlmaLinux and Rocky Linux 9 and 10, RHEL 9 and 10, Ubuntu 24.04 and 26.04, Debian 13
bc is a calculator for the command line with arbitrary precision. It is handy in shell scripts, which can only do whole-number arithmetic on their own, and for quick sums while you work on a server. We tested every example below with bc 1.07.1 on AlmaLinux 9.
Install
dnf install bc # AlmaLinux, Rocky Linux, RHEL apt install bc # Ubuntu, Debian
Quick calculations
echo "2^10" | bc # 1024 echo "scale=4; 10/3" | bc # 3.3333 echo "(512*1024)/60" | bc # whole-number result
By default bc divides without decimals. scale sets the number of decimal places.
The math library
echo "s(1)" | bc -l # sine of 1 radian: .84147098480789650665 echo "sqrt(2)" | bc -l echo "l(100)/l(10)" | bc -l # logarithm base 10 of 100
-l loads the math library (sine s, cosine c, arctangent a, natural logarithm l, exponent e) and sets scale=20.
Number bases
echo "obase=2; 42" | bc # 101010 (decimal to binary) echo "ibase=16; FF" | bc # 255 (hexadecimal to decimal) echo "obase=16; 255" | bc # FF
Hexadecimal digits must be upper case. Set obase before ibase when you use both, because values after ibase are read in the new base.
In scripts
used=$(df --output=used -k / | tail -1) total=$(df --output=size -k / | tail -1) echo "scale=1; $used*100/$total" | bc
This prints the percentage of the root file system in use, with one decimal.
Interactive use
Run bc -l without input to get a calculator prompt. Type expressions and press Enter; quit leaves. The variable last holds the previous result.
Official documentation: GNU bc manual.
