Flash sales work because they create urgency that overrides the typical "I'll think about it" consumer response. The psychology is well-documented: scarcity and time limits drive faster decisions. SMS is the only marketing channel fast enough to deliver that urgency in real time.
Email flash sale campaigns often see the majority of their traffic arrive 2–6 hours after sending — by which time a 4-hour sale is over. SMS flash sale campaigns see 60–70% of clicks within the first 30 minutes.
Percentage discount: "25% off everything" — simple, easy to communicate, works for broad audiences.
Dollar amount off: "$20 off orders over $80" — works better for higher AOV stores; the dollar amount feels more concrete for mid-range purchases.
BOGO: "Buy one, get one 50% off" — strong for consumables, apparel, and gift-purchase occasions.
Category flash sale: "All outerwear 30% off for 6 hours" — easier to merchandise than sitewide, allows you to move specific inventory.
Exclusive SKU drop: "50 units only — [Product] just dropped at $79. First come, first served." — creates genuine scarcity rather than manufactured urgency.
Day of week: Tuesday, Wednesday, and Thursday consistently see the highest flash sale conversion rates. Monday feels too soon; Friday shoppers are distracted; weekends are busy.
Time of day: 10 AM–12 PM and 7 PM–9 PM are the two peak windows. Lunch hour (12–1 PM) performs well for impulse buys. Evening sends work well for leisure categories.
Sale duration: 4–8 hours for maximum urgency. Sales longer than 24 hours lose the "flash" element that drives immediate action. Sales shorter than 2 hours don't give enough purchase window.
Advance notice: Consider sending a teaser 24 hours before: "Tomorrow only: something big is happening. Stay tuned." This builds anticipation and sets up a two-message sequence.
The copy formula for flash sale SMS:
"[Brand] | [Sale Name]: [Offer] — [Time limit]. [CTA]: [link]"
Examples:
Message 1 (Launch): Sent when the sale goes live.
"Canon Co: Flash Sale is LIVE — 25% off everything for the next 5 hours. Shop now before it's gone: [link]"
Message 2 (Final reminder, 1 hour before end): Only to subscribers who didn't click Message 1.
"Last chance: Canon Co's Flash Sale ends in 60 minutes. 25% off everything: [link] — Reply STOP to opt out"
Don't send the final reminder to people who already clicked. They know the sale is on. Sending them a second message is annoying, not helpful.
Once per month is sustainable for most audiences. More than twice per month and you start training subscribers to wait for discounts, which erodes full-price purchasing behavior. Flash sales should feel like a special event, not a weekly occurrence.
Maria Jensen
SMS Marketing Strategist at Textcanon
Helping businesses reach their audience through effective, compliant SMS marketing. Writing about strategy, deliverability, and growth.