What Size Softbox Do I Need?

The short answer: a 24-inch box is the right default for faces, a 16-inch box is right for a desk or a tabletop product setup, and half-body or full-body portraits want something larger or two boxes working together. But the number on the box is only half the story, because softness is not a property of the softbox — it is a relationship between the box, the subject and the distance between them.

The one rule that decides everything

Light is soft when the source is large relative to the subject. That is the entire mechanism. A large source sends light at a face from many slightly different angles, so the edges of shadows are gradual and the dark side fills in gently. A small source sends light from effectively one angle, so shadow edges are abrupt — the hard, unflattering look of a bare bulb or midday sun.

Two consequences follow, and they are the two things people miss. First, distance changes softness. What matters is how big the box appears from where the subject is standing, so moving a box closer makes it effectively larger and softer, and pulling it back makes it smaller and harder. A 16-inch box a foot away can be softer than a 36-inch box across the room.

Second, the right size depends on the subject. A 24-inch box is huge next to a coffee mug, comfortably large next to a face, and quite small next to a standing adult. The same box is a soft light and a hard light depending on what you point it at, which is why “what size softbox” has no single answer.

Sizes by what you are shooting

Head-and-shoulders video and portraits. A 24-inch box at roughly three to four feet is the practical sweet spot, and it is why most two-light kits are built around that size. It is bigger than a face, so the light is genuinely soft; it is small enough to place in a normal room without choreography; and it is easy to keep out of a tight frame. If you want softer, move it closer before you buy bigger.

Half-body and seated two-person shots. Now your subject is three or four feet of frame, and a 24-inch box starts behaving like a harder source with visible falloff from the near shoulder to the far one. Go larger, or place two boxes side by side and feather them so their coverage overlaps. This is the point where a single lamp on a Bowens mount with a bigger modifier beats a kit.

Full-body portraits.Six feet of subject needs a very large source to stay soft top to bottom, which in a home studio usually means two boxes stacked or a large box placed further back and accepted as somewhat harder. A strip box — long and narrow — is the specialist tool here, because it matches the shape of a standing figure and spills less onto the background.

Tabletop and product work. The easy case. Your subject is a few inches tall, so even a 16-inch box placed close is an enormous source, and you get the smooth gradients that make a product look three-dimensional. Cheap compact kits do genuinely professional work here, which is the single best-value fact in lighting. More detail in lights for product photography.

Why bigger is not automatically better

It is tempting to buy the largest box available and consider the problem solved. Three reasons not to. A big box in a small room cannot be placed properly — if you cannot get it close and at the right angle, its size is wasted. A big box is hard to keep out of a wide frame, and the moment you push it back out of shot you have reduced its apparent size anyway. And a big box spills: light goes everywhere, including onto the background you were trying to keep dark or a different colour.

The useful formulation is this: buy the largest box you can comfortably place close to your subject in the room you actually have. In most homes that is a 24-inch box, not a 36-inch one, and the people who end up happiest with their lighting are usually the ones who bought a modest box and learned to move it.

Shape, and whether it matters

Less than size, but not nothing. An octagonal box leaves a round catchlight in the eyes, which many photographers prefer for portraits because it resembles a daylight source. A rectangular box leaves a window-shaped catchlight, which looks natural for the same reason. A strip box is long and narrow, which makes it excellent for edge-lighting a figure and for keeping light off a nearby wall.

What does matter is whether the box takes a grid. A grid is a honeycomb fabric that clips to the front and narrows the beam, so the light still arrives soft but stops spreading across the room. On a small set, that one accessory does more for control than going up a box size — it is how you light a face without lighting the wall behind it. If you are weighing a box against the cheaper alternative, our softbox vs umbrella comparison covers where each one ends up.

Which of these fits your situation

If you are shooting talking-head video or portraits, the 24-inch Neewer pair is the straightforward answer: the right default size, two of them, with stands, for very little. The compromise is fixed-output bulbs, so you set brightness by moving the light — which, as above, also changes softness.

If you are working at a desk or on a table, the 16-inch EMART kit is the better buy and the adjustable 3000-6000K colour is a real advantage in a room that has its own warm lighting. Small boxes are not a compromise for small subjects; they are the correct tool, and they do not dominate a room you also have to live in.

If you would rather buy the light and choose the box separately, do that. A COB light on a Bowens mount like the Amaran 100x S accepts any modifier the standard fits, so you can run a 24-inch box for faces and a larger one for half-body work from the same lamp, and dim it smoothly rather than walking it backwards. It costs more and arrives in more pieces, and nothing in it becomes disposable. The full comparison lives in our softbox lighting kit roundup.