kqalc — Full qalculate power in KRunner

Features

Math

qc 2+2 qc sqrt(2) qc sin(pi/4) qc 2^64

Currency conversion

qc 5000 GEL to USD qc 100 EUR to KZT

Unit conversion

qc 100 km/h to mph qc 180 lbs to kg

Equations

qc x^2 = 9 qc solve(2x+5=15, x)

Exact & approximate

Both results shown side by side where useful

Clipboard

Select result to copy. Wayland & X11.

Install

Requires KDE Plasma 6, libqalculate (qalc CLI), and wl-copy (Wayland) or xclip (X11).

KDE Store

Open Discover, go to Krunner → System Runners and install kqalc.

On Arch, install packagekit-qt6 first — Plasma lists it as optional, but the tool that installs KRunner plugins is linked against it and will not start without it.

Debian / Ubuntu

Add the APT repository and install:

curl -fsSL https://noctuum.github.io/kqalc/gpg-key.asc \
  | sudo tee /usr/share/keyrings/kqalc.asc > /dev/null

echo "deb [signed-by=/usr/share/keyrings/kqalc.asc] https://noctuum.github.io/kqalc stable main" \
  | sudo tee /etc/apt/sources.list.d/kqalc.list

sudo apt update && sudo apt install kqalc

Arch Linux (AUR)

Install with your preferred AUR helper:

paru -S kqalc-bin

Nix

Run directly or add to your flake inputs:

nix run github:noctuum/kqalc

From source

Requires Go 1.22+:

git clone https://github.com/noctuum/kqalc.git
cd kqalc
./install.sh

After installing

kqalc runs as a D-Bus service, started on demand the first time you type qc. What it takes to get there depends on how you installed.

From source. Nothing — install.sh starts kqalc for you, so qc 2+2 works right away.

From a package — AUR, Debian/Ubuntu. Restart KRunner so it picks up the new plugin:

kquitapp6 krunner && kstart6 krunner

From the KDE Store. Usually nothing. If qc finds nothing at all, start kqalc by hand once — Discover unpacks the archive under ~/.local/share/krunner-sources/, and the kqalc file inside it is the one to run. This only happens on a machine that has never had a user D-Bus service before. From your next login on, it starts on demand like any other runner.

Nix. nix run builds and runs the binary without installing it, so KRunner never sees the plugin metadata. Add the package to a profile or to your system or home-manager configuration instead, then restart KRunner.

Usage

Open KRunner (Alt+Space) and type:

qc <expression>

The qc prefix triggers kqalc. Results appear instantly — select to copy to clipboard.