---
title: "Custom ad units and sizes"
description: "Admin → Custom ad units & sizes is the catalogue every size dropdown in the platform draws from — add a size, decide which placement types and which side (inventory, campaigns) see it, and know why a size you added is not offered where you expected."
type: "howto"
audience: [admin]
keywords: [custom ad size, ad unit, ad unit catalogue, size dropdown, inventory side, campaigns side, placement types, any size deprecated, custom unit, 728x90, 300x250, new size not offered]
ui_path: "Admin → Creatives & tags → Custom ad units & sizes"
---

Fetch the complete documentation index at: https://epom.com/ad-server/docs/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version.

# Custom ad units and sizes

An *ad unit* is a named creative size — *Leaderboard (728x90)*, *Medium Rectangle (300x250)*.
The catalogue under **Admin → Creatives & tags → Custom ad units & sizes** is what every size
dropdown in the product is drawn from: the placement's **Size** combo, the creative's **Ad unit**
combo, the header-bidding slot editor and the auto-placement template. Each unit says which
placement types it fits and whether the supply side, the demand side or both may pick it.

**Example.** A publisher wants a 970×250 billboard above the fold. Add a unit *Billboard
(970x250)*, width 970, height 250, **Site Placement** ticked, **Inventory side** and **Campaigns
side** on. From the next page load the network manager picks *Billboard (970x250)* on a new site
placement, and the advertiser's creative form offers it under **Ad unit**; a creative uploaded at
that size matches the placement.

## Typical scenarios

| You want | Set | Result |
|---|---|---|
| A new standard size on both sides | Title `Billboard (970x250)`, 970 × 250, Site Placement, Inventory side + Campaigns side | Offered on site placements and on creatives |
| A size publishers may sell but advertisers should not pick directly | Campaigns side off | Placements offer it; the creative **Ad unit** combo does not |
| A mobile-only size | Tick **Mobile Site Placement** only | Never offered on a desktop Site Placement |
| A "whatever fits" slot on video players | A unit with **Custom** on and 0 × 0, **Video Placement** ticked (the shipped *Custom Video Player*) | The placement form shows manual width/height inputs instead |
| Retire a size nobody should pick | Untick every placement type (or delete it, if no live placement uses it) | A unit with no placement type appears nowhere |

## Step by step

1. Open **Admin → Creatives & tags → Custom ad units & sizes**. The grid shows **Title**,
   **Placement types**, **Width**, **Height**, **Custom**, **Inventory side** and **Campaigns
   side** for every unit, the shipped catalogue included.

   ![Custom ad units and sizes grid showing the placement-types, Custom, Inventory side and Campaigns side columns](https://epom.com/docs-images/ad-server/admin-tools/custom-ad-sizes-grid.webp)

2. Click **Add** (or tick a row and **Edit**). Type the **Title** — the convention in the shipped
   catalogue is `Name (WxH)` — and the **Width** and **Height** in pixels.
3. Tick the **Placement types** the size fits, and leave **Inventory side** and **Campaigns side**
   ticked unless one side should not see it.
4. **Save**. The toast reads *Done*. The size is offered from the next page load wherever its
   placement types and sides say.
5. To remove a unit, tick it and click **Delete**. A size used by any non-deleted placement is
   refused — see the caveats.

## Caveats and exceptions

- **Who can do this.** An admin role with the **Custom Ad Units & Sizes** Admin UI permission.
  Opening the URL without it shows *Record not found.* Network managers, publishers and
  advertisers never see this page; they meet the result in their size dropdowns.
- **Where a size shows up is decided entirely here.** **Placement types** plus the two side flags
  are the *whole* answer — there is no per-role tick-list that also has to be satisfied before a
  new size appears:

  | Where | Needs |
  |---|---|
  | Placement **Size** combo | matching placement type **+ Inventory side** |
  | Creative **Ad unit** combo, advertiser grid size filter | matching placement type **+ Campaigns side** |
  | Header-bidding slot editor | **Inventory side** + a non-zero width and height, and a placement type that matches the slot's kind |
  | Template test page | **Inventory side** — and only for a Site-placement template; the page offers no size for any other type |
  | **Auto placements** *Size* combo | matching placement type, and the unit must **not** be *Custom* |

- **A size with no placement type ticked appears nowhere at all.** The lookup is driven entirely
  by the placement-type set, so an empty set matches no query.
- **Custom units are size-less placeholders.** Picking one on a placement or a creative reveals
  manual width/height inputs rather than fixing the size. Each placement type conventionally has
  one — *Custom*, *Custom Mobile*, *Custom Video Player*, *Custom Application*. A custom unit is
  deliberately excluded from the **Auto placements** *Size* combo — a size-less unit cannot be an
  auto-placement template, even though the same unit is selectable on a hand-made placement of
  that type. (The header-bidding slot editor drops it too, for the different reason that it
  requires a non-zero width and height.)
- **Deleting a size used by any non-deleted placement is refused** with *Cannot delete size, it is
  used by not deleted placements*. The check looks at placements only — a size used solely by
  creatives deletes without a warning, and those creatives lose their ad unit.
- ***Any size (deprecated)* is a legacy flag, not a convenience.** It describes a placement slot,
  so every creative-side list — the creative form, the mass banner upload and the REST banner
  ad-unit list — drops units carrying it, whatever their **Campaigns side** box says. A creative
  given such a unit would be stored at 0×0 and match no placement. Do not set it on new units.
  The **Auto placements** size list is the one exception: it keeps the *Any Size* unit — see
  [Other admin tools](https://epom.com/ad-server/docs/guides/admin/admin-tools.md#auto-placements).

## Not working?

| Symptom | Likely cause | Check |
|---|---|---|
| The new size is not in the placement's **Size** combo | The placement's type is not ticked, or **Inventory side** is off | Edit the unit → Placement types, Inventory side |
| The new size is not in the creative's **Ad unit** combo | **Campaigns side** is off, the placement type does not match, or *Any size (deprecated)* is on | Edit the unit |
| The size is missing from the header-bidding slot editor | Width or height is 0, or the unit is Custom | Give it real dimensions |
| The size is missing from **Auto placements** | The unit is Custom | Pick a sized unit for the template |
| **Delete** is refused | A non-deleted placement still uses the size | Change those placements' size first; a creative-only use does not block |
| A creative shows 0×0 | It was given a unit with *Any size (deprecated)* | Re-pick a real unit on the creative |

## Reference

| Field | What it does |
|---|---|
| **Title** | The label shown in every size dropdown. Required, max 255 characters. Convention in the shipped catalogue is `Name (WxH)`, e.g. *Leaderboard (728x90)*. |
| **Width** / **Height** | Pixel dimensions, 0–3000 each. Left at 0 for a *Custom* unit, whose dimensions are typed per placement instead. |
| **Custom** | Marks the unit as a size-less placeholder. Picking it on a placement or a creative reveals manual width/height inputs rather than fixing the size. |
| **Any size (deprecated)** | Legacy wildcard flag. Do not set it on new units. Creative-side lists skip units carrying it — see the caveats. |
| **Inventory side** | Offer this size on the supply side — placements, header-bidding slots, template test pages. Ticked on a new unit. |
| **Campaigns side** | Offer this size on the demand side — creative *Ad unit* combos and the advertiser grid filters. Ticked on a new unit. |
| **Placement types** | Eight checkboxes: *Site Placement*, *Mobile Site Placement*, *Non-standard Placement*, *Video Placement*, *Application Placement*, *Email Placement*, *Click-through Placement* and *Native Placement*. A size is only offered on a placement of a ticked type. |

| Permission | Lets you |
|---|---|
| **Custom Ad Units & Sizes** (Admin UI) | Open the page, add, edit and delete units. |

Over the API, `GET /rest-api/ad-units.do` lists the ad units of each placement type — the same
catalogue the placement and banner endpoints size an entity with; see
[Creative ad specs](https://epom.com/ad-server/docs/reference/creative-ad-specs.md) for the shipped catalogue.

## Related

- [Other admin tools](https://epom.com/ad-server/docs/guides/admin/admin-tools.md) — the other small admin pages and the shared routine
- [Create a placement](https://epom.com/ad-server/docs/guides/inventory/placements-create.md) — placement types and sizes
- [Creative ad specs](https://epom.com/ad-server/docs/reference/creative-ad-specs.md) — where the ad units in the Size combo come from
- [Header bidding](https://epom.com/ad-server/docs/guides/inventory/header-bidding.md) — the slot editor