diff --git a/qpms/lattices.h b/qpms/lattices.h
index 4c08ce4..30aae93 100644
--- a/qpms/lattices.h
+++ b/qpms/lattices.h
@@ -315,6 +315,7 @@ int l2d_cellCornersWS_arr(cart2_t i1, cart2_t i2,  cart2_t *oarr, double rtol);
 int l2d_reciprocalBasis1(cart2_t b1, cart2_t b2, cart2_t *rb1, cart2_t *rb2);
 int l2d_reciprocalBasis2pi(cart2_t b1, cart2_t b2, cart2_t *rb1, cart2_t *rb2);
 
+double l2d_unitcell_area(cart2_t b1, cart2_t b2);
 
 // returns the radius of inscribed circle of a hexagon (or rectangle/square if applicable) created by the shortest base triple
 double l2d_hexWebInCircleRadius(cart2_t b1, cart2_t b2);
diff --git a/qpms/lattices2d.c b/qpms/lattices2d.c
index 09475b4..d939471 100644
--- a/qpms/lattices2d.c
+++ b/qpms/lattices2d.c
@@ -827,5 +827,11 @@ double l2d_hexWebInCircleRadius(cart2_t i1, cart2_t i2) {
 }
 
 
+double l2d_unitcell_area(cart2_t b1, cart2_t b2) {
+  l2d_reduceBasis(b1, b2, &b1, &b2);
+  const double det = b1.x * b2.y - b1.y * b2.x;
+  return fabs(det);
+}
+