Your parcel weighs 510 grams and you just paid 1kg rates — courier billing isn't linear, it's a staircase. The slabs are the reason tiny packaging decisions have outsized cost consequences.
The staircase
Couriers bill at weight breaks: 500g, 1kg, 1.5kg, 2kg and so on. 500g pays the 500g rate; 501g pays the 1kg rate — the extra gram costs as much as the first 500. It's not a scam, it's stair pricing; it's also why your rate card's '₹60' applies to a weight band, not a weight.
The packaging implication
Every gram of packaging counts — the poly mailer that saves 40g over a box keeps you under the slab edge. Sellers fighting to keep parcels at 'under 500g' are fighting the staircase, not the scale. Volumetric stacks on top: whichever of actual-or-volumetric is higher gets slab-priced.
Where it bites hardest
Products near slab edges: the 480g SKU is fine, the 520g version pays double. The fix is spec-level: lighter mailer, trimmer box, remove the insert if it's the gram that crosses.
The multi-slab discount illusion
Heavier parcels cost less per-kg — the 2kg slab's per-500g price beats the 500g slab's. Combined shipments (3 items in one parcel) exploit this: one 1.4kg parcel ships cheaper than three 500g ones. Bundles aren't just AOV — they're freight math.
Pakka Parcel runs the whole stack described here — one place for every carrier.
See how →The playbook
Know your products' slab positions
Weigh packed — not product, parcel.
Pack to stay under the edge
The 20g of excess packaging is a ₹60 bill.
Bundle to fill slabs
1.4kg single beats 3× 500g parcels.
Remember volumetric stacks
The higher of the two weights slabs it.
