Find the target
Get the recommended CG range from the manual — usually a % of wing chord or mm from the leading edge.
Measure
Fully assemble the plane (battery in), lift it at the wing root where the target CG sits. Nose drops = nose-heavy; tail drops = tail-heavy.
Compute
Use the CG Calculator to express where it balances as % of chord, then compare with the spec. See CG explained for why % matters.
Adjust
Move the battery forward/aft first, then add weight if needed. Re-check after every change.
Safety
Never maiden a plane outside the published CG range — a tail-heavy first flight is usually a short one.