Weight Slabs: Why 20 Grams Can Cost ₹38

Nobody charges you per gram. Rate cards are staircases, and everything about shipping cost management follows from where the steps are.

How a card is written

A typical card:

Base: ₹42 up to 500 g. Additional: ₹38 per 500 g or part thereof.

“Or part thereof” is the important phrase. It means:

Parcel weight	Steps	Freight
480 g	base	₹42
500 g	base	₹42
505 g	base + 1	₹80
990 g	base + 1	₹80
1,010 g	base + 2	₹118

Five grams over 500 costs the same as 495 grams over 500. There is no proportionality anywhere on this card.

What that means in practice

Your median parcel weight should sit just under a boundary, not just over. If most of your parcels land at 520–560 g, you are paying ₹80 for something that would cost ₹42 at 490 g. Twenty to seventy grams of packaging change is worth ₹38 on every single order.

A bigger first slab beats a lower base rate. Compare two offers on a card where your median parcel is 700 g:

Card	Base	Your 700 g parcel
A: ₹38 up to 500 g, +₹36 per 500 g	₹38	₹74
B: ₹44 up to 1 kg, +₹34 per 500 g	₹44	₹44

Card A has the better headline rate and costs 68% more on the parcel you actually ship. This is the single most useful thing to know when comparing quotes.

The audit worth running

Export 90 days of shipments. Bucket the chargeable weights in 50 g bands. Look at where the mass of your volume sits relative to your card’s boundaries.

Two things usually fall out: a cluster sitting just above a boundary that packaging can fix, and a boundary in the wrong place that a renegotiated card can fix.

Frequently asked questions

Why is my 505 g parcel charged like a 1 kg parcel?

Because the card charges per 500 g “or part thereof”. Five grams into the second step is a full step.

Should I optimise for the base slab or the additional slab?

Whichever your median parcel sits in. Look at your actual distribution rather than the headline number.

Do all carriers use 500 g slabs?

Common, but not universal. 250 g, 500 g and 1 kg first slabs all exist, and the first slab size matters more than the rate attached to it.