Free tool · nothing is uploaded
LUT resizer
Resample a 3D LUT onto a different grid — and find out what the resample actually cost, measured on your file rather than assumed.
Drop a .cube LUT here
Resampled in your browser. Nothing is uploaded.
What the number after the cube means
A 3D LUT does not store an answer for every possible colour — there are 16.7 million of those in 8-bit alone. It stores answers on a regular lattice and interpolates between them. The size is how many steps that lattice has along each axis, so a 33³ LUT holds 33 × 33 × 33 = 35,937 sampled colours and a 65³ one holds 274,625.
| Grid | Entries | Where you meet it |
|---|---|---|
| 17³ | 4,913 | LUT boxes, on-camera monitors, game engines |
| 33³ | 35,937 | The default nearly everywhere |
| 65³ | 274,625 | Conversion LUTs, hard hue keys, mastering |
Why the error figure is worth reading
Resampling downward throws away lattice points, and how much that hurts depends on what sits between them. A film emulation that is essentially a smooth curve survives 65³ → 17³ with a shift too small to see. A LUT with a hard key — one that pulls a specific hue and leaves its neighbours alone — has detail between the points, and losing them softens exactly the edge that made the look work.
The percentage shown is the worst single-channel disagreement between the original and the resample, sampled across the whole colour space. It is a measurement of your file, not an average over LUTs in general, and it is the reason to trust or distrust a particular conversion.
Frequently asked questions
What does the size of a LUT actually mean?
It is the resolution of a three-dimensional lookup grid. A 33³ LUT stores 35,937 sampled colours; anything falling between them is interpolated. A larger grid samples the transform more finely, which matters when the LUT does something abrupt, and matters not at all when it does something smooth.
Which size should I use?
33³ is the default nearly everywhere and the right answer unless something tells you otherwise. Use 65³ when a LUT has hard hue keys or steep contrast that visibly bands at 33³. Use 17³ only when a target demands it — some hardware LUT boxes, older camera monitors and a few game engines cap there.
Does making a LUT bigger improve it?
No. Interpolating up to 65³ produces a larger file describing exactly the transform the smaller grid already described — the extra points are computed from the existing ones, not recovered from anywhere. It is worth doing only to satisfy software that refuses the size you have.
How much does downsizing cost?
It depends entirely on the LUT, which is why this tool measures it rather than generalising. Both versions are sampled on a common grid and the largest single-channel disagreement is reported as a percentage. Under about 0.5% is invisible. Above 1% will show on smooth gradients — skies and skin especially — and the preview is there to confirm it.
Why is 33³ so common?
It is the size Adobe's .cube documentation uses in its examples and what most export dialogs default to, so it propagated. It is also a genuinely sensible compromise: fine enough for almost every creative look, small enough that the file stays under a megabyte and a GPU can hold it comfortably.
Is my LUT uploaded?
No. The file is parsed locally, resampled on your CPU and previewed on your own GPU. Nothing leaves your machine.