Is flat shipping fair when my products have different weights?
A single flat shipping fee overcharges light parcels and undercharges heavy ones, and the balance depends entirely on the mix of orders you actually receive.
If every product you sell weighs about the same, a flat shipping fee is easy and fair. Most catalogues are not like that. You might sell a 200 g pouch and a 1 kg jar side by side. One flat fee for both means one of them is subsidising the other.
A small example
Let us use illustrative costs. Say shipping a 200 g parcel costs you Rs 40, and shipping a 1 kg parcel costs Rs 100. You charge a flat Rs 60 for both.
- Light parcel: you collect Rs 60, pay Rs 40, and gain Rs 20.
- Heavy parcel: you collect Rs 60, pay Rs 100, and lose Rs 40.
Whether the flat fee works depends on how many of each you sell.
It all depends on the mix
If three of every four orders are light and one is heavy:
- Three light orders gain 3 times Rs 20, which is Rs 60.
- One heavy order loses Rs 40.
- Net: Rs 20 gained across four orders, or Rs 5 per order.
That is fine. The flat fee works out slightly ahead.
Now flip the mix so one order is light and three are heavy:
- One light order gains Rs 20.
- Three heavy orders lose 3 times Rs 40, which is Rs 120.
- Net: a loss of Rs 100 over four orders, or Rs 25 each.
Same prices, same fee, very different result. Your product mix is the hidden variable. It also shifts over time. A festive season that boosts a heavy gift item can turn a profitable flat fee into a loss quickly.
What fairness means here
A light-parcel customer who pays Rs 60 for a Rs 40 delivery may feel overcharged, especially if they compare with other sites. A heavy-parcel buyer gets a bargain you cannot sustain. For you, fairness mostly means not losing money on any large group of orders.
Your options
- Keep a flat fee and set it at your weighted average cost. Weigh your recent orders, work out the average shipping cost, and charge that.
- Split into two or three flat tiers by weight, such as light and heavy products.
- Use free shipping above a threshold so large baskets are covered by margin. See choosing a threshold from margin.
- Lower the weight of your heavy items through packaging. Read trimming packaging weight.
Start by knowing your numbers
Before you pick, list your top ten products with their packed weights and the shipping cost for each at your usual zone. Do this once and keep it in a sheet. Our note on writing product weight and dimensions covers how to capture it cleanly. Then count last month's orders by weight group to see your real mix.
Compare with the charge gap
If your flat fee is simply too low across the board, you have a different issue, covered in what happens when you charge Rs 49 but pay Rs 70.
Takeaway
A flat fee is not unfair by nature. It is risky when your products differ widely and your mix can swing. Run the small test above with your own costs. If a plausible change in mix would push you into loss, add tiers or a threshold. If your mix is steady and the average works out, keep the simple flat fee and revisit it each quarter.