Step by step
Set up a flash sale countdown timer
Create a fixed timer for the sale's end
A flash sale ends at the same moment for everyone, so use a fixed timer. Set the end date, time and time zone, for example Sunday at 11:59pm Eastern. On Basic and up you can describe the sale to flashtimer's AI instead, “48-hour flash sale, 25% off, urgent”, and it drafts the countdown, style and copy into the editor. It counts the 48 hours from now, so set the exact end in the date picker.
Pick a style that reads at a glance
Choose from pill, boxes, circles, compact, minimal or rings. For a sale under 72 hours, show hours, minutes and seconds large and hide days if they would read zero. Apply your brand kit colors, and on paid plans use a transparent background so the timer sits on your email's own colors.
Set the expiry message or fallback image
Write what readers see after the deadline, such as “This sale has ended. Join the list for the next one.” On Basic and up, upload a fallback image that links visually to your next offer. Nobody who opens late sees a countdown to a deal they can no longer get.
Embed it in every email of the sale
Paste the image URL into an image block, or the HTML snippet into a code block, in your launch, reminder and last-chance emails. All of them use the same timer, so the time left is always right. On Pro and up, connected platforms such as Klaviyo or Mailchimp get the timer inserted into a draft campaign for you.
Test and schedule the sequence
Send yourself a test in Gmail, Apple Mail and Outlook. Check the deadline in your text, preheader and timer agree, and that the button lands on a page where the discount applies. Then schedule all sends at once so nothing depends on someone remembering on Sunday night.
How long a flash sale should run
Most flash sales run 24, 48 or 72 hours. 24 hours is the most urgent and suits a single headline product or a one-day event; you get one launch email and one reminder. 48 hours gives readers who check email once a day two chances to see it and is the safest default. 72 hours fits a weekend sale (Friday morning to Sunday night) and leaves room for a mid-sale email.
Whatever you pick, decide the end time before you write a word, and write it in your readers' time zone. “Ends Sunday at 11:59pm ET” is clear; “ends this weekend” is not. The timer then makes that one deadline visible in every email without you editing anything between sends.
A 48-hour flash sale email schedule
Here is a schedule you can copy for a 48-hour sale running Friday 9am to Sunday 9am. Every email embeds the same fixed timer:
- Optional teaser, Thursday afternoon. “Tomorrow, 9am: 25% off for 48 hours.” A separate fixed timer counts to the start.
- Launch, Friday 9am. “Our 48-hour sale is on: 25% off everything.” Timer shows 47 hours and change.
- Reminder, Saturday morning. Only to people who didn't click or buy. “24 hours left: 25% off ends Sunday at 9am.”
- Last chance, Sunday early morning or Saturday evening. “Final hours: 25% off ends at 9am.” Short email, timer at the top, one button.
Flash sale email subject lines that pair with a timer
The subject line gets the open; the timer does the rest. Name the offer and the deadline, keep it under about 50 characters so it isn't cut off on phones, and save capitals and alarm emoji for the last-chance email. A few patterns that work with a countdown inside:
Put the deadline in the preheader too, for example “Ends Sunday 9am ET, no code needed.” For more ideas by sale type, see our flash sale subject lines guide.
- “48 hours only: 25% off everything”
- “Your 25% off ends tomorrow at 9am”
- “12 hours left on the flash sale”
- “Last call: the sale ends at 9am”
The last-chance resend
The last-chance email is usually the strongest email of a short sale, and the timer is why it works: by then it shows hours, not days. Send it to everyone who hasn't bought, and consider a version to non-openers of the launch email with a new subject line. Because the timer renders on open, the same image shows the right time to someone who opens at 6am and someone who opens at 8:55am.
Make the email shorter than the launch: the timer, one sentence, one button. Send it with enough time left to act, usually 6–12 hours before the end, not 30 minutes. Readers who open after the deadline see your expiry message or fallback image instead of a stuck clock.
Store-synced flash sale timers
If your flash sale is a discount in Shopify or WooCommerce, connect your store on Pro and up. The discount becomes a timer, and the store's webhooks keep the end date in sync, so extending the sale by six hours in Shopify moves the countdown in every email already sent. See the Shopify email countdown timer setup and the WooCommerce countdown timer setup.
On Business, a timer for a Shopify, PrestaShop, Magento or Squarespace product can also expire when it sells out, which is the honest way to run a limited-quantity drop. Planning the rest of the sale, from list building to post-sale analysis? Read how to prepare for a flash sale.
Flash sale email countdowns in every inbox
The timer is an animated GIF rendered when the email is opened, so it works in any email platform that shows images: Gmail, Apple Mail, Yahoo and Outlook on the web, Mac and mobile. Classic Outlook for Windows (2007–2019, and newer versions with Windows animations turned off) shows only the first frame, which is the correct time left when opened but doesn't tick.
Apple Mail Privacy Protection pre-fetches images when the email arrives. By default those fetches get the live countdown as it stood then; on Pro and up you can set Apple Mail options to show them a message, your fallback image or nothing instead of a possibly stale countdown. In every case, the deadline written in the email text is your backup.
Questions
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Keep reading
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