Flash sale

A flash sale is a deep discount that runs for a short time, usually counted in hours, to pull buyers in at the same moment. On e-commerce marketplaces, a flash sale is a time-slot promotion tool, such as Shopee’s Flash Sale or Shop Flash Sale.

What is a flash sale?

Cambridge Dictionary defines a flash sale as a very short period of time when a store sells products at much lower prices than usual (Cambridge Dictionary, flash sale, accessed November 2026). The difference from an ordinary discount is time pressure: shoppers know the deal is about to end, so they decide faster.

Flash sales on Shopee

Shopee has two kinds. For Shopee’s Flash Sale, sellers register products and wait for Shopee’s approval. Shop Flash Sale is a promotion tool sellers create themselves in Seller Centre: pick the products, date and time slot, with no need to wait for Shopee’s review. One product cannot run in both at the same time; if the slots overlap, the system prioritizes Shopee’s Flash Sale. The same product can have several Shop Flash Sale slots in one day (Shopee Seller Centre Vietnam, What is Shop Flash Sale, accessed November 2026).

Pricing a flash sale without losing money

Minimum flash sale price = (Cost of goods + Cost per order) / (1 – Platform fee rate)

Example (hypothetical): cost of goods VND 120,000, packing and handling VND 10,000 per order, assumed platform fees of 20% of the selling price. The minimum price is 130,000 / 0.8 = VND 162,500. With a list price of VND 250,000, a 35% discount is break-even, before ads. To earn VND 20,000 per order, the price must be at least VND 187,500, a discount of no more than 25%.

A deliberate loss-making flash sale can still make sense if the goal is new customers or product ranking. In that case, book the loss as a customer acquisition cost and compare it with what ads would cost for the same number of customers.

Flash sales and Vietnam’s promotion rules

Vietnam’s E-commerce Law No. 122/2025/QH15, in force since July 1, 2026, requires platforms with online ordering to clearly show the promotion that applies before the buyer places the order (Article 12), and to publish sales conditions and restrictions, including time limits (Article 11) (Vietnam Government Gazette, Law No. 122/2025/QH15, published January 2026).

On discount limits, Decree 239/2026/ND-CP of June 26, 2026, effective on signing, repealed Article 7 and Clause 5 of Article 10 of Decree 81/2018/ND-CP (Vietnam Government Portal, Decree No. 239/2026/ND-CP, accessed November 2026). Those were the rules on the maximum discount rate and the total number of discount days per year for one brand of goods (LuatVietnam, What is new in trade promotion under Decree 239/2026/ND-CP, August 2026). The decree also tasks the Ministry of Industry and Trade with setting the maximum discount rate, so many older guides on discount limits are out of date. Before a deep-discount campaign, check the Ministry’s current rules.

Measuring a flash sale

• Orders and GMV in the slot versus the same slot on a normal day.
• Share of new customers among flash sale buyers.
• Contribution profit after platform fees, vouchers and ads, not just sales.
• Cancellation and return rates for flash sale orders versus full-price orders.
• Sales over the next 7 days: do buyers come back at full price, or wait for the next sale?

Flash sales often run alongside mega sale days and livestreams. A preparation calendar is in our 11.11 sale plan: a 30-day checklist; how to work out the profit of a live session is in our guide to live selling on TikTok Shop and Shopee.

Frequently asked questions

How is a flash sale different from a voucher?

A flash sale cuts the product price directly during the slot, so anyone who arrives in time gets that price. A voucher is a code shoppers have to collect and apply, often with a minimum order value.

What is the best time slot for a flash sale?

There is no single best slot for every shop. Test a few slots and compare orders and profit per slot using your own shop’s sales data on the marketplace.

Adtek does not operate marketplace stores for clients. If you need an ad plan to run alongside marketplace flash sales, see our Brand Commerce page.