Rule of Thirds Calculator
Grid lines and intersections in pixels for any frame, with the golden-ratio grid beside them and what a centred social crop leaves of your composition.
Frame 1,920 × 1,080 pixels
Aspect ratio 1.7778
Grid thirds, at 33.3% and 66.7%
Vertical lines, from the left
line 1 640.0 px
line 2 1,280.0 px
Horizontal lines, from the top
line 1 360.0 px
line 2 720.0 px
The four intersections
top left 640.0, 360.0
top right 1,280.0, 360.0
bottom left 640.0, 720.0
bottom right 1,280.0, 720.0
The other grid, for comparison
vertical 733.4 and 1,186.6
horizontal 412.5 and 667.5
the difference 93.4 px on the first vertical, 4.9% of the frame
Centre and diagonals
centre 960.0, 540.0
diagonal length 2,202.9 px
If this gets cropped
square, 1:1 1,080 × 1,080 from 420, 0
portrait, 4:5 864 × 1,080 from 528, 0
story, 9:16 608 × 1,080 from 656, 0
landscape, 16:9 1,920 × 1,080 from 0, 0
The rule of thirds is a convention rather than a law. It first appears
in John Thomas Smith's Remarks on Rural Scenery of 1797, as advice about
the proportion of light to dark in a landscape, and became a
compositional rule by repetition. It works because an off-centre subject
usually reads as more dynamic than a centred one.
The phi grid puts the lines at 38.2 and 61.8 percent instead of 33.3 and
66.7. On this frame that is a difference of 93.4 pixels, about 4.9
percent of the width, which is smaller than most people's placement
accuracy. Deciding to place the subject deliberately matters more than
which grid you use.
Centred composition is not a mistake. Symmetry, portraits looking
straight at the camera, and anything where the subject is the whole
point all work better centred, and a rule applied without looking is
worse than no rule.
Put the eyes on the top third line in a portrait, not the head. That is
the single most useful application of the grid, and it is what most
portrait crops get wrong.
For a landscape, the horizon goes on a third line rather than through
the middle. Which third depends on whether the sky or the ground is the
subject, and the answer is usually whichever has more going on in it.
The crop is what ruins the composition. A frame composed on thirds and
then cropped square for a social profile loses both vertical lines, so
compose for the crop you will actually publish, and the centred-crop
figures above show what survives.
These are pixel positions, not a guide layer. Most editors can show a
thirds overlay and a phi overlay directly, which is faster than
measuring, and the numbers here are for placing something exactly or for
writing a guide into a template.
Output is valid and updates as you type.
Fix the highlighted fields to update the output.
The rule of thirds is a convention, not a law. It first appears in John Thomas Smith’s Remarks on Rural Scenery of 1797, as advice about the proportion of light to dark in a landscape, and became a compositional rule by repetition. It works because an off-centre subject usually reads as more dynamic than a centred one, and it is wrong often enough that every good photographer breaks it deliberately.
The golden-ratio grid is the same idea with different numbers: lines at 38.2 and 61.8 percent instead of 33.3 and 66.7. On a 1920-pixel frame that is 93 pixels apart, about five percent of the width, which is smaller than most people’s placement accuracy.
Both are printed here, along with the centre, the diagonals, and what a centred social crop leaves of the composition, because the crop is usually what ruins it rather than the grid.
How to use
- Put in the frame size in pixels.
- Read the line positions and the four intersections.
- Check the crop section before you compose, not after.
Example
A 1920 × 1080 frame:
Vertical lines, from the left
line 1 640.0 px
line 2 1,280.0 px
Horizontal lines, from the top
line 1 360.0 px
line 2 720.0 px
The four intersections
top left 640.0, 360.0
top right 1,280.0, 360.0
bottom left 640.0, 720.0
bottom right 1,280.0, 720.0
The other grid, for comparison
vertical 733.4 and 1,186.6
the difference 93.4 px on the first vertical, 4.9% of the frame
If this gets cropped
square, 1:1 1,080 × 1,080 from 420, 0
portrait, 4:5 864 × 1,080 from 528, 0
story, 9:16 608 × 1,080 from 656, 0A square crop of that frame keeps pixels 420 to 1500, which throws away both vertical third lines. A composition built on them survives the crop only if the subject happens to be near the centre.
Pitfalls
Centred composition is not a mistake. Symmetry, a portrait looking straight at the camera, and anything where the subject is the whole point all work better centred. A rule applied without looking is worse than no rule.
Put the eyes on the top third line, not the head. That is the single most useful application of the grid, and it is what most automatic portrait crops get wrong.
The horizon goes on a third line, not through the middle. Which third depends on whether the sky or the ground is the subject, and the answer is usually whichever has more going on in it.
The crop decides the composition. A frame composed on thirds and then cropped square for a profile loses both vertical lines. Compose for the crop you will actually publish, and use the figures above to see what survives.
The difference between the two grids is smaller than your aim. Five percent of the frame is less than the variation in where anybody actually places a subject. Arguing about thirds versus phi is a way of avoiding the harder question of what the subject is.
These are positions, not a guide layer. Most editors show a thirds overlay and a phi overlay directly, which is faster than measuring. These numbers are for placing something exactly, or for writing guides into a template.
Compatibility
Arithmetic in the browser: nothing is uploaded and nothing is stored. No image is read, only the dimensions you type.
The thirds are exactly a third and two thirds of each dimension. The phi lines are at 1 − 1/φ and 1/φ, which is 0.381966 and 0.618034, and they are symmetric about the centre, which the test suite checks.
The crop figures are the largest centred crop of each ratio that fits inside the frame, given as size
and offset so they can be used directly in an editor or a CSS object-position. The ratios covered are
the common social ones: square, 4:5 portrait, 9:16 story and 16:9 landscape.
Frequently asked questions
Is the rule of thirds real?
Should I use the phi grid instead?
Where do I put the horizon?
How do I keep composition through social crops?
Does this work for web layout?
object-position takes percentages directly. For layout structure, a grid system is the better tool.