Your bias's birthday is coming up, and you've decided: "Okay, I'm putting up a support ad in Korea." Then, for a lot of first-timers, the next thought is where everything stalls — "…wait, how many days should it actually run?"
Just one day? A week? A whole month? You look it up and all you get is "it depends on the media," which somehow leaves you more confused than before. So let's sort it out. This is a plain-English guide to choosing the display period for a K-pop support ad (a birthday ad) in Seoul, Korea — no jargon, just how to pick a length you won't regret.
💡 The short answer, first
You don't get to pick "any number of days" freely. Instead, you choose from the fixed sales units each medium offers (1 day / 7 days / 15 days / 1 month…). If it's your first time, solo or a small group, starting your thinking around "about one week" is the safest bet. Here's why.
A display period isn't "free days" — it's the medium's sales unit
The most important thing to know up front: a support ad usually can't be booked for one exact day of your choosing, like "just November 20th." A subway light box, a street digital signage screen — each one has its own minimum sales unit, and you build your schedule so your bias's special day falls inside that unit.
So "choosing a display period" is really almost the same as "choosing which sales unit — meaning which medium — you want." Here are the typical units to keep in your head.
| Typical sales unit | Where you'll see it | Best when |
|---|---|---|
| 1 day – a few days | Some street video walls / building LED boards | You want the birthday itself, pinpoint, on a smaller budget |
| 1 week (7 days) | Station digital signage / some video walls | You want fans to have a few relaxed days to come by |
| 15 days | Digital boards and similar | A bit longer than a week, but a month feels like too much |
| 1 month (30 days) | Subway light boxes (printed posters) and similar | A debut anniversary or milestone you want to keep up longer |
*Units shift by medium, location, and season. Treat the table as a rough guide, not a fixed rulebook.
By medium: how few days can you actually book?
Let's get a little more specific. Even within "subway advertising," the minimum unit changes between the printed-poster type and the digital type. Roughly, it breaks down like this.
| Media type | Typical minimum | How it shows | Cost feel |
|---|---|---|---|
| Station light box (printed poster) | From 1 month | Lit and up the whole period — fans can linger over it | From the low hundreds of thousands of KRW |
| Digital board | From 15 days | Video or still images shown on rotation | From the low hundreds of thousands of KRW |
| Station digital signage / video wall | From 7 days (1 week) | Loops in turn with other ads, over and over | From the low hundreds of thousands of KRW |
| Some building LED boards | 1 day is possible | Short and concentrated — good for the day itself | Varies a lot by location |
⚠️ Only some digital media can actually do "just the birthday, one day." That dream station light box usually runs by the month, so "put it in the station for one day's cost" generally isn't a thing. Knowing that early makes planning so much easier.
1 day, 1 week, 1 month: how to choose by your goal
Once you know the units, the rest is simple: pick by what matters most to you. Choose by goal and the hesitation just melts away.
1 – a few days
You want day-of impact
Keep the budget lean and make the birthday itself shine. Short and intense — just note that only certain media allow it.
1 week
You want fans to come by, unhurried
It catches at least one weekend, so fans who travel or work can still make it. The "hard-to-get-wrong" line we'd recommend to first-timers.
1 month
You want it to last
Great for a debut anniversary or milestone you want to celebrate for a while. Costs more, so choose it when your goal and budget genuinely call for it.
A quick "which one's me?" table
| Your situation | Period to aim for |
|---|---|
| Modest budget + day-of impact above all | 1 – a few days (on a short-run medium) |
| First time + you want fans to visit too | 1 week (catching a weekend) |
| Celebrating a debut anniversary or milestone, longer | 15 days – 1 month |
| Running it from overseas for the first time | About 1 week, on a medium that sends confirmation photos |
Three checks so you don't regret the length
People who get the period wrong tend to make the same few mistakes. Flip that around, and nailing just these three will head off almost any regret.
Put the birthday in the middle of the run, not at the edge
Booking the exact day only is riskier than it sounds. The first morning can still be install time, so your real "lit" hours on day one may only be half a day. Instead of "the day only," go for "a few days around the day" and give yourself breathing room.
Catch at least one weekend
Support ads live on a culture of "fans come see it, take photos, and share it." A weekday-only run means fans with school, work, or a long trip can miss it entirely. Even one Saturday–Sunday in the window widens who can actually show up.
Work backward from your budget — book only what you need
A classic regret: assuming "longer is always better," booking a full month, and ending up covering the gap out of pocket. Decide your budget first, then pick a period that fits inside it. Often "a great spot and a great medium, for just as long as you need" beats sheer length.
✅ A mini checklist before you lock in the period
- Is the goal "day-of impact" or "keep it up a while"?
- What's your realistic budget — does the cost fit inside it?
- Is the birthday on a weekday? Can you catch a weekend?
- If you can't be there, does the medium send confirmation photos?
- What's the minimum unit for the medium you're eyeing?
Once the period's set: book 2–3 months ahead, relax with confirmation photos
Here's something just as important as "how many days" — "when you book." Popular stations and slots fill up early, so if you want to lock in your ideal period plus location, it's realistic to start moving roughly 2–3 months before the run. Design submissions have deadlines too, so the sooner you decide the period, the more options stay open.
And the worry that lingers when you're running it from overseas: "If it's only up a short time, will it just end without me ever knowing it really ran?" That one's solved by confirmation photos from local staff. Even if you can't fly over, you get real photos of your ad while it's up — so whether it's a week or a single day, you still get proof. No need to stretch the run "just in case, to feel safe."
💡 Because it's operated locally and directly in Korea, there's no middleman markup — so the same period on the same medium tends to cost less, which makes "just what you need" easy to choose. Even solo or in a small group, individuals can apply, and you can start small with a shorter run.
Start by browsing the actual periods and media
Don't overthink the display period. Go in the order "goal → budget → the medium's minimum unit," and the right length for your bias falls into place on its own. The quickest way there is simply to see which media are out there and what period each one starts from.
Your bias's day — how many days will you run it?
Check display periods and costs by medium, right now.
See support ad media & periods →*Display periods, minimum units, and costs vary by medium and season — check the latest terms on each medium's page. For the photos and design in your support ad, please follow the guidelines of the celebrity's agency or official channels.
