Every figure on this page is a dimension from the floor, in millimetres. Where we quote published guidance we say whose it is.
The one rule worth memorising
A plinth is not sized to the room. It is sized to the object standing on it, and to the eyes of the person looking at it.
Plinth height + half the object's height = 1,200–1,400mm.
That puts the visual centre of the object in the band where almost everyone can see it comfortably. The Smithsonian's accessible exhibition guidelines put the preferred centreline for exhibit content at 1,370mm, inside a comfortable viewing range of 1,220–1,675mm. Aim at 1,370mm and you will rarely be wrong.
Worked example: a 280mm ceramic vessel. Half its height is 140mm. 1,370 − 140 = 1,230mm — which is taller than most people expect, and taller than we would actually recommend, for the reason in the next section. A 900mm or 1,000mm plinth is the honest answer.
Why we pull the number down
Because not everyone is standing. The same guidance gives the average eye level of a wheelchair user as 1,090–1,295mm. A plinth optimised purely for a standing adult puts a small object above that line, and the person seated in front of it sees the underside.
Two consequences worth designing around:
- Small objects that must be legible from a seated position should have their top surface no higher than 1,015mm.
- Anything laid flat — a manuscript, a coin tray, a plan — needs a deck at 915mm or lower, or it cannot be read at all from a chair.
If the display has to serve both, 900–1,000mm is the compromise that fails nobody badly. That is why the 900mm plinth outsells everything else we make, roughly three to one.
Heights, and what each one is actually for
| Height | Object height it suits | Use it when |
|---|---|---|
| 200–300mm | 900mm and over | A floor-standing sculpture that needs its footprint declared rather than its height raised. Also the right base under a tall vitrine. |
| 450mm | 700–1,200mm | Busts, torsos, large vessels. Reads as furniture at this height, so keep the top plate tight to the object. |
| 600mm | 600–900mm | Mid-size sculpture. A comfortable height to walk around. |
| 750mm | 450–750mm | Model architecture, groups of objects, anything meant to be looked down into. |
| 900mm | 250–500mm | The workhorse. Object centre lands at 1,050–1,150mm: standing viewers look slightly down, seated viewers still see the whole thing. |
| 1,000mm | 150–350mm | Jewellery, small bronzes, mineral specimens. The top is still at the seated limit. |
| 1,100–1,200mm | 100–300mm | Standing-first displays, retail, and objects inside a case where the deck sits below the glass line. Above comfortable seated eye level — a deliberate choice, not a default. |
| 1,400mm and over | Any | Objects intended to be read from below, and window displays seen by someone standing outside on a pavement 1,500mm away. |
Top plate: the margin nobody allows enough of
The most common specifying error we see is a plinth top cut to the object's footprint plus a few millimetres. It looks tight in a drawing and precarious in a room.
- Minimum 100mm of clear plate on every side of the object.
- 150–200mm if the object is tall relative to its base, or if visitors will lean in.
- Square the plate to the object, not to the room. A round vessel on a square top wants more margin than a rectangular box does.
Against that, don't overshoot: a top plate much wider than the object invites people to put things on it. Coffee cups end up on generous plinths.
Stability, and the numbers we build to
A freestanding plinth is a tall box with a small footprint, which is the definition of a tipping hazard if it is specified carelessly.
- We build to a base dimension of at least one third of the height in the narrower direction. A 1,200mm plinth therefore has a base no smaller than 400 × 400mm.
- Above 1,100mm with a base under that ratio, we ballast the plinth or supply floor fixings. Say so at quote stage and we will detail it.
- Every plinth we make carries a stated top-plate load in kilogrammes. It is a static figure for a centred load. An off-centre load, or a visitor leaning on the edge, is a different case — ask us.
Groups of plinths
Three plinths at 890, 900 and 910mm look like a mistake. Three at 600, 900 and 1,100mm look like a decision.
- Step heights by at least 150mm so the difference reads as intentional from across the room.
- Odd numbers group more easily than even ones, and a group of three needs no symmetry to look resolved.
- Keep top-plate sizes in a family — varying both height and footprint at once produces clutter.
Leave room to walk
The heights are wasted if people cannot get to them. The same accessibility guidance gives:
- 915mm minimum for a one-way route.
- 1,525mm minimum for two-way circulation, and the same figure for a wheelchair turning circle.
- 760 × 1,220mm of clear floor for one wheelchair to stand and look.
Measure those gaps between the widest points of the plinths, not between their centres. And watch projections: an object or shelf that sticks out more than 100mm into a route at between 685mm and 2,030mm above the floor is not detectable by a long cane, which makes it a hazard rather than a display.
Light, briefly
Height and light are the same decision. A plinth positioned under a spot that was aimed at a 600mm object will not light a 1,100mm one. Working figures: 100 lux minimum to see an object at all, 100–300 lux to read a label beside it, and 50 lux as the ceiling where conservation limits apply. Our guide to specifying a display case covers the conservation side properly.
If you are not a museum
Retail and shopfit
The buying eye works higher than the looking eye. Hero product sits at 1,400–1,600mm; below 900mm reads as clearance whether you mean it to or not. Window plinths are the exception — the viewer is outside, further away, and often slightly below the shop floor, so go taller than feels right indoors.
Collectors at home
Domestic ceilings and domestic furniture change the arithmetic. A plinth in a room with a sofa is read against the sofa back at roughly 800mm. A 900mm plinth beside it looks correct; a 1,200mm one looks like it wandered in from a gallery. If the piece is to be seen from a seated position most of the time, drop to 600–750mm and accept it.
Plant displays
Two constraints beat aesthetics here. You have to be able to water the top tier without a step — keep it under 1,500mm — and the lower tiers need clearance for the plant, not the pot, so measure the mature spread and add 100mm. Staging is also the one application where we recommend slatted tops as standard, for drainage and airflow.
Still unsure?
Send us the object's height, width and depth, its weight, and one sentence about who will be looking at it and from where. We will come back with a height and a top-plate size. There is no charge for that and you are not obliged to buy anything. Contact us.
Sources
Viewing heights, seated eye level, reach ranges, circulation widths and lux figures are taken from the Smithsonian Guidelines for Accessible Exhibition Design (Smithsonian Institution Accessibility Program). Everything about load, ratio and top-plate margin is our own workshop practice, not published standard.
This page is general guidance. It is not a structural calculation and it is not an access audit. Where public safety or statutory access compliance is in question, take advice from a qualified professional.