Flash sales move units fast. The problem is that many shop owners run the sale first and do the math afterward, only to find they spent several hours selling at a loss. This is about setting the discount floor from the real landed cost of 1688 goods, so a flash sale drives orders without destroying margin.
Why flash sales lose money more often than expected
Goods imported from 1688 arrive carrying several cost layers: the product price, domestic China shipping to a consolidation warehouse, international freight to Vietnam, customs and import fees, and the order-service fee if you use an agent. When you set the normal selling price, you priced all of that in and left a margin on top. When you run a flash sale, the percentage you see on screen is a discount off the listed price, not off the real landed cost.
A concrete example. Listed price: 180,000 VND. Real landed cost (all fees included): 140,000 VND. You run a 30% flash sale, landing at 126,000 VND. Result: you lose 14,000 VND per unit before platform fees and ads. A 30% discount does not sound extreme, but when your starting margin is only 20 to 25 percent, a 30% cut off the listed price wipes out the entire margin and eats into principal.
Build the real landed cost first
The first step is not deciding how many percent to cut. The first step is knowing the exact figure: how much real money does it take to get one unit into your warehouse.
The components of real landed cost for 1688 goods:
- The 1688 product price converted to dong at the current rate. The yuan-to-dong rate moves, currently around VND 3,600 per yuan (check it at calculation time rather than locking in a fixed number).
- Domestic China shipping from the factory to the consolidation warehouse. Usually small, but easy to miss.
- International freight to Vietnam. Sea freight typically takes 18 to 30 days. Air is faster but considerably more expensive. Heavy or bulky goods carry a much bigger freight bill.
- Customs fees and import duties. The rate depends on the product type and HS code. Confirm the correct number for your specific category.
- Order-service fees if you use a sourcing agent. Typically a few percent of the order value.
- Defect shrinkage. Not every batch arrives intact. If your average defect rate runs 3 to 5 percent, spread that cost across the units you actually sell.
Add everything up: that total is the real landed cost per unit. This is the absolute floor. No flash-sale price should touch or fall below this number.
Set a target margin for the flash sale
A flash sale is not supposed to lose money, and it does not need to earn as much as a normal day. The realistic goal is to accept a lower margin in exchange for higher volume over a short window, while staying in the black.
Before picking a discount, answer one question: what is the minimum acceptable margin for this sale? That decision belongs to each operator based on their goal, but a few practical frames:
- Clearing old stock. A thin but positive margin is fine. You are not trying to win on profit here. You are recovering cash to reinvest in something that moves faster.
- Driving orders in a campaign (11.11, shop anniversary, pushing platform rank). You can accept a tighter margin, but check whether total revenue from the campaign covers your campaign ad spend.
- Attracting new customers to upsell later. The flash-sale item is the hook, and the margin comes from the follow-up order. This only makes sense if you actually have a follow-up plan for those buyers.
The formula for a safe discount ceiling
Once you have real landed cost and a minimum margin target, the safe discount ceiling is straightforward:
Flash-sale floor price = Real landed cost + Platform fee + Minimum target margin
Where:
- Platform fee is the cut the platform takes per order. The rate varies by platform (TikTok Shop, Shopee, Lazada) and product category, so confirm the specific number for your listing.
- Minimum target margin is whatever amount you decided above: 5%, 8%, 10% on landed cost, depending on your objective.
An illustrative example (reference figures, not universal):
Real landed cost per unit: 120,000 VND. Platform fee: 12,000 VND. Minimum margin target: 8,000 VND per unit. Floor price = 120,000 + 12,000 + 8,000 = 140,000 VND. Normal listed price: 175,000 VND. A flash sale can go as low as 140,000 VND, which is a 20% discount. If you push to 25% off and land at 131,000 VND, you are now below the floor and losing money on every order.
Do not forget ad spend inside the flash sale
Many flash sales run alongside paid traffic. If you are spending on ads to push visitors into the sale, that spend is also part of the cost per order sold.
Simple approach: divide total ad spend for the event by the number of orders it generates. That is the allocated ad cost per order. Add it to landed cost before you calculate the floor.
The difficulty is that before the event you do not know how many orders you will get. A practical way to handle this: set a minimum order target for the ad spend to make sense. If you spend 500,000 VND on ads and need at least 50 orders, ad cost per order is 10,000 VND. If only 20 orders come in, ad cost per unit jumps to 25,000 VND and the whole margin plan collapses.
This is why a flash sale with no ads is generally safer on margin, while a flash sale with ad spend needs a unit-volume target and a fallback plan if volume falls short.
When it makes sense to cut deeper for dead stock
There is one reasonable case for a steeper discount: stock that has been sitting too long and is at risk of dying completely. In that situation, selling slightly below landed cost is better than holding inventory until no one will buy it at any price.
Even then, know the exact number. If a 40% discount off the listed price means losing 15,000 VND per unit, and you have 200 units left, the total loss is 3 million VND. Compare that to the cost of holding the stock longer and the probability that it never sells. This is a calculated business decision, not a panic discount.
Calculated price-cutting is different from gut-feel price-cutting. The second kind is what actually loses money.
Common mistakes when setting flash-sale prices
A few errors worth avoiding:
- Discounting by percentage off the listed price without looking at real margin. "25% off" sounds controlled, but if your starting margin is only 20%, you are selling at a loss.
- Copying the discount level of a competitor. A competitor may have a different landed cost (larger volumes, a better factory relationship, or frankly they may not know they are losing money either). Their price is not your benchmark.
- Leaving the platform fee out of the floor calculation. Platform fees are charged on the selling price, not on profit. Miss this and the whole calculation is wrong.
- Running the same discount percentage across multiple platforms at once. Platform fees differ, which means the real per-order cost differs. A discount that works on one platform can be a loss on another.
Bottom line
Flash sales perform best when you know exactly how far you can go. The discount floor is not a feeling, not what the competitor did, but a specific number: landed cost plus platform fee plus the minimum margin you are willing to accept. Knowing that number before you set the sale price is the difference between a shop owner who makes money from the busiest hours of the week and one who works for free during them.