Prime Day and Prime Big Deal Days

Table of Contents

  1. Definition
  2. Why Prime Day matters for marketing
  3. How it works
    1. Event structure
    2. Competing retailer events
    3. How to calculate Prime Day performance
  4. How to utilize Prime Day
  5. Prime Day compared with other sales events
  6. Best practices
  7. Future trends
  8. FAQs
  9. Related Terms
  10. Listen: The Agile Brand podcast
  11. Further reading on Agile Brand Guide
  12. Sources

Definition

Prime Day is Amazon’s annual members-only sales event, offering discounts to Amazon Prime subscribers across Amazon’s marketplaces. Amazon held the first Prime Day on July 15, 2015, in nine countries, timed to the company’s 20th anniversary, and pitched it as a deal event bigger than Black Friday. Despite the name, it hasn’t been a single day since 2016. It grew to 30 hours in 2017, 36 hours in 2018, 48 hours in 2019, and four days in 2025.

Prime Big Deal Days is Amazon’s second members-only sales event, held in October. It launched in 2022 as the Prime Early Access Sale (October 11–12, 2022) and was renamed Prime Big Deal Days in 2023. It’s often called “Prime Day 2” or “October Prime Day,” and it functions as an early start to holiday shopping.

2026 dates:

  • Prime Day 2026: June 23–26, in 22 countries including the U.S., the UK, Canada, and Mexico. It was the first June Prime Day since 2021 (June 21–22).
  • Prime Big Deal Days 2026: October 6–7.

Prime Day has become a retail event beyond Amazon. Walmart, Target, Best Buy, and other retailers schedule competing sales on the same dates. Adobe Analytics, which tracks U.S. online spending across retailers rather than Amazon’s sales alone, measured $26.4 billion in U.S. online spending during Prime Day 2026.

See also: Black Friday and Cyber Monday (BFCM) · Retail Media Network · Commerce Media Network (CMN) · Buy Now, Pay Later (BNPL)

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Why Prime Day matters for marketing

For brands that sell on Amazon, Prime Day is one of the biggest sales events of the year and often the most competitive advertising auction outside of Cyber Week. For brands that don’t sell on Amazon, it’s still a demand spike they have to plan around, because shoppers comparison-shop across retailers.

The numbers are large and growing. Adobe measured U.S. online spending across all retailers during each Prime Day:

YearEvent lengthU.S. online spend (Adobe)Average per day
20222 days$11.9 billion~$6.0 billion
20232 days$12.7 billion~$6.4 billion
20242 days$14.2 billion~$7.1 billion
20254 days$24.1 billion~$6.0 billion
20264 days$26.4 billion~$6.6 billion

The jump from 2024 to 2025 looks like 70% growth, but it mostly reflects the event doubling in length. On a per-day basis, average spending actually fell in 2025, then recovered in 2026. That’s worth remembering whenever Prime Day “record” headlines come out.

Prime Big Deal Days is smaller but growing steadily. U.S. online shoppers spent $9.86 billion across the two-day October 2026 event, up 8.5% from $9.09 billion in 2025, according to Adobe.

Amazon doesn’t publish dollar sales for either event. It reports units sold, Prime member savings, and seller records instead, and it has called third-party estimates of Prime Day sales often inaccurate. The Adobe figures are the most widely cited, but they measure the whole U.S. online market during the event, not Amazon alone.

Prime Day matters to marketers in several ways:

  • Retail media. Brands raise Amazon Ads budgets for sponsored products, sponsored brands, and display placements during the event. See Retail Media Network.
  • Customer acquisition. Prime Day deals introduce new customers to brands, which Amazon Ads measures with its new-to-brand metrics.
  • Halo effects. Spending rises at other retailers during Prime Day. Brands with their own DTC sites and wholesale partners often see lifts outside Amazon too.
  • Competitive response. Retailers that don’t participate still have to decide whether to match prices, run their own events, or hold firm.
  • Holiday pull-forward. Prime Big Deal Days pulls some holiday spending into early October, which changes how brands pace Q4 budgets.
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How it works

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Event structure

EventTypical timingLengthEligibility
Prime DayMid-summer (July in most years; June in 2021 and 2026; October in 2020)4 days since 2025Prime members; deals available across participating Amazon countries
Prime Big Deal DaysEarly October2 daysPrime members

Deal types include Lightning Deals (limited-time, limited-quantity offers), Prime Exclusive Discounts, coupons, and deals on Amazon devices. Sellers apply for deal placements months ahead, and Amazon sets eligibility requirements on price, ratings, and inventory.

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Competing retailer events

Other retailers now run events around Prime Day dates, usually open to all shoppers rather than members only. In 2026, Walmart ran its Walmart Deals event from June 22 to 28, starting a day before Prime Day and ending two days after. Target ran Circle Deal Days from June 23 to 26, matching Prime Day exactly. These events are a big reason Adobe’s Prime Day totals cover the whole online market rather than just Amazon.

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How to calculate Prime Day performance

1. Event sales lift

Sales lift (%) = (Average daily sales during event − Average daily sales in baseline period) ÷ Average daily sales in baseline period × 100

Use the 2–4 weeks before the event’s “lead-in” period as the baseline, since some shoppers hold purchases ahead of known deals.

2. Advertising cost of sales (ACoS) and ROAS

ACoS (%) = Ad spend ÷ Ad-attributed sales × 100
ROAS = Ad-attributed sales ÷ Ad spend

ACoS is Amazon’s standard ad efficiency metric. It’s the inverse of return on ad spend (ROAS). An ACoS of 25% equals a ROAS of 4.0.

3. Total advertising cost of sales (TACoS)

TACoS (%) = Ad spend ÷ Total sales (ad-attributed and organic) × 100

TACoS shows whether advertising is lifting total sales or just buying sales that would have happened anyway.

4. New-to-brand share

New-to-brand share (%) = Orders from first-time brand customers ÷ Total orders × 100

5. Off-Amazon halo

Halo lift (%) = (DTC or other-retailer sales during Prime Day − Baseline sales) ÷ Baseline sales × 100

A worked example (illustrative, not benchmark data): a kitchen-appliance brand averages $40,000 a day on Amazon. Over the four days of Prime Day, it sells $520,000, or $130,000 a day, for a sales lift of 225%. It spends $78,000 on Amazon Ads, which drive $312,000 in attributed sales. ACoS is 25%, ROAS is 4.0, and TACoS is 15%. If 1,800 of its 4,000 orders came from first-time customers, new-to-brand share is 45%.

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How to utilize Prime Day

Common use cases for brands selling on Amazon:

  • Product launches and ranking. Higher sales velocity during Prime Day can improve organic search ranking on Amazon after the event ends.
  • Customer acquisition. Discounts on entry-level products bring in first-time buyers, who can then be retargeted through Amazon Ads.
  • Inventory clearance. Older models and excess stock move faster with Lightning Deals and coupons.
  • Subscribe & Save sign-ups. Consumable brands use the event to start recurring orders.

Common use cases for brands and retailers not tied to Amazon:

  • Competing sales. Running a sale on or around the same dates captures shoppers who are already in a buying mood.
  • Value positioning. Retailers like Walmart and Target emphasize that their events don’t require a paid membership.
  • Counter-programming. Some DTC brands deliberately avoid discounting during Prime Day and promote full-price launches or loyalty perks instead.

For holiday planning:

  • Prime Big Deal Days as a test. Brands use the October event to test offers, creative, and audiences ahead of Cyber Week.
  • Early gifting. Toys, electronics, and seasonal categories see sharp spikes. During Prime Big Deal Days 2026, Adobe saw toys up 158% and headphones and speakers up 300% compared with average September spending.
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Prime Day compared with other sales events

EventOrganizerTimingMembership required?Length (2026)U.S. online spend (Adobe, latest)
Prime DayAmazonJune/JulyYes, Prime4 days$26.4B (2026)
Prime Big Deal DaysAmazonOctoberYes, Prime2 days$9.86B (2026)
Walmart DealsWalmartOverlaps Prime Day and OctoberNo7 days (June 2026)Not reported separately
Target Circle Deal Days / Circle WeekTargetOverlaps Prime Day and fallFree Target Circle membership for some deals4 days (June 2026)Not reported separately
Cyber WeekIndustry-wideThanksgiving through Cyber MondayNo5 days$44.2B (2025)
Singles’ Day (11.11)Alibaba and other Chinese retailersNovember 11NoVariesMostly outside the U.S.
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Best practices

  1. Apply for deals early. Amazon deal submissions close weeks to months before the event. Confirm eligibility on price history, ratings, and inventory.
  2. Plan inventory around Amazon’s deadlines. Running out of stock mid-event ends deals and can hurt organic ranking. Inbound shipments to Amazon fulfillment centers have cutoff dates well before the event.
  3. Run a lead-in, event, and lead-out. Build awareness and retargeting audiences in the weeks before Prime Day, push hardest during the event, then retarget shoppers who browsed but didn’t buy.
  4. Budget for higher ad costs. Competition raises cost-per-click during the event. Set daily budgets high enough that campaigns don’t run out early in the day.
  5. Watch TACoS, not just ACoS. High ad efficiency means little if total sales didn’t move.
  6. Protect margin. Model deal pricing, Amazon fees, ad spend, and fulfillment costs together. A deep discount plus a high ACoS can produce revenue with no profit.
  7. Coordinate pricing across channels. Prime Day deals are visible to every price-tracking tool and AI shopping assistant. Big gaps between Amazon and DTC prices create channel conflict and can confuse shoppers.
  8. Measure the halo. Track DTC site traffic, branded search, and other-retailer sales during the event to see the full effect.
  9. Treat Prime Big Deal Days as a holiday rehearsal. Test offers and creative in October, then scale what works for Cyber Week.
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AI-referred shopping. Generative AI traffic to U.S. retail sites rose 89% year over year during Prime Day 2026, and AI-referred visitors converted about 40% better than other traffic, according to Adobe. In 2025, the same traffic had converted 23% worse. That swing is one of the fastest changes Adobe has measured in a single year. Product data quality and machine-readable offers matter more as shopping agents compare deals across retailers.

Longer events, lower per-day intensity. The move to four days raised total spend but lowered the average per day. More retailers are also running week-long competing events. Prime Day increasingly behaves like a sales season rather than a single spike.

Shifting dates. Amazon moved Prime Day to June in 2026 after holding it in July in 2025, and it didn’t publicly explain why. Retailers and advertisers can’t assume a fixed July window when planning budgets.

Smaller baskets, more essentials. Numerator reported average Amazon household spending of $143 during Prime Day 2026, down 8.3% from 2025, with everyday items such as protein shakes and trash bags among the top sellers. Shoppers are using Prime Day to stock up on routine purchases, not just big-ticket items.

BNPL and mobile growth. Buy now, pay later accounted for $2.1 billion in Prime Day 2026 online spending, up 9.5%, and mobile devices drove 54.2% of sales, according to Adobe.

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FAQs

When is Prime Day 2026? Prime Day 2026 ran from June 23 to June 26 in the U.S. and 21 other countries. Some countries, including Australia, Brazil, India, and Japan, hold their Prime Day later in the summer.

When is Prime Big Deal Days 2026? Prime Big Deal Days 2026 ran October 6–7.

Is Prime Day only one day? No. It started as a 24-hour event in 2015, but it has run longer every year since 2017. It’s been four days since 2025.

Do you need Prime to shop Prime Day? Yes, for Amazon’s Prime Day deals. Competing events from Walmart, Target, and other retailers usually don’t require a paid membership.

How much do shoppers spend on Prime Day? U.S. shoppers spent $26.4 billion online across all retailers during Prime Day 2026, according to Adobe. Amazon doesn’t disclose its own Prime Day sales in dollars.

What’s the difference between Prime Day and Prime Big Deal Days? Prime Day is Amazon’s main summer event, now four days long. Prime Big Deal Days is a shorter, two-day October event aimed at early holiday shopping.

Why do other retailers run sales during Prime Day? Prime Day drives a surge in online shopping across the whole market. Competing retailers run their own events to capture shoppers who are already comparing prices.

What is ACoS? Advertising cost of sales is ad spend divided by ad-attributed sales. It’s Amazon’s standard ad efficiency metric and the inverse of ROAS.

Does Prime Day affect holiday sales? Prime Big Deal Days in particular pulls some holiday spending into October. Adobe and other analysts also treat it as an early read on holiday demand and discounting.

Should a brand participate in Prime Day? It depends on margins, inventory, and channel strategy. Brands that rely on Amazon for a large share of sales usually participate. DTC-focused brands sometimes run their own events or avoid discounting to protect pricing.

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  1. Black Friday and Cyber Monday (BFCM)
  2. Cyber Week
  3. Retail Media Network
  4. Commerce Media Network (CMN)
  5. Return on Ad Spend (ROAS)
  6. Incremental Return on Ad Spend (iROAS)
  7. Buy Now, Pay Later (BNPL)
  8. Share of Voice (SOV)
  9. Shopping Agent
  10. Peak Season Readiness
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Listen: The Agile Brand podcast

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Further reading on Agile Brand Guide

Statistics reflect Prime Day 2026 (June) and Prime Big Deal Days 2026 (October) results published as of October 2026. Figures are updated after each event.

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Sources

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