A stable home reference saves repeated compass checks. Establish it carefully before adding a permanent floor line or changing a shared prayer space.
Use the address location
Calculate the bearing using the coordinates of your home or prayer room rather than a distant city center. Record the location and displayed angle so another person can reproduce the result. Do not infer direction from the building entrance.
Establish a reliable north reference
Check a north-aligned map against identifiable building edges or outdoor landmarks. If using a physical magnetic compass, account for local magnetic declination. A phone may already apply a correction; check its north reference before adding one yourself.
Try a temporary marker
Use removable tape to mark the direction, then check again away from nearby metal or electronics. Compare with an independent map-based method, not just a second app reading the same phone sensor. Avoid presenting small differences between unstable readings as meaningful precision.
Review shared spaces with others
For a mosque or shared prayer room, involve the responsible people and a knowledgeable local adviser before making permanent changes. This guide is for measurement, not deciding whether earlier prayers were valid or what tolerances apply. Take those questions to a qualified scholar.
Common questions
Should a prayer mat follow the room walls?
Only if the walls happen to align with the calculated direction. Building edges are not automatically Qibla references.
Do I need to measure before every prayer?
A fixed location has a stable calculated bearing. Recheck if the original measurement or marker is in doubt; religious requirements are a question for a scholar.
Are two apps an independent check?
Not if both rely on the same disturbed compass sensor. A map or another reliable reference is a better independent check.