diff --git a/src/setup.jl b/src/setup.jl
index fdb45ac..13fc84a 100644
--- a/src/setup.jl
+++ b/src/setup.jl
@@ -88,7 +88,7 @@ function gen_sim_consts(
     n_particles = grid_n^2
 
     if half_box_len == 0.0
-        half_box_len = sqrt(n_particles * π / packing_fraction) * σ / 4
+        half_box_len = sqrt(n_particles * π / packing_fraction) * σ * 2^(-11 / 6)
     elseif packing_fraction != DEFAULT_PACKING_FRACTION
         error("You can not specify half_box_len and packing_fraction at the same time!")
     else