Plan a Raised Bed Before You Order Soil
Work out fill volume, allow for settling, and space plants for airflow rather than maximum count.
A raised bed is mostly a volume problem before it is a planting problem. Length, width, and fill depth give the number to order, and getting it wrong means either a second delivery charge or a pile of surplus mix.
Leave a lip and allow for settling
Filling to the rim makes watering messy and mulching impossible. Leave a few centimetres, then order five to ten percent extra, because fresh mixes compact noticeably through the first season.
Space for airflow, not for count
Tighter spacing raises plant count and lowers yield per plant, while restricting airflow in humid weather. Packet spacing reflects the mature width of that specific variety and should override any general grid.
Offset rows fit more at the same spacing
Triangular or offset planting fits roughly fifteen percent more plants than a square grid at identical spacing, because the gaps between rows do more work.