Print size

When you are looking at a 1:1 photo in lightroom, what size print would be equivalent?

Well, how many pixels in your image and then what is the dot spacing of your monitor? How many DPI are you going to print at?

My 22" diagonal monitor is 19" wide. At screen resolution of 1920, we have about 100 pixels per inch. A 6000 x 4000 (24mp) 80D photo would need to be printed 60"x40" to equal your 1:1 view.

eddieb1 wrote in post #18155139
When you are looking at a 1:1 photo in lightroom, what size print would be equivalent?

Your question has no meaningful answer because there is no relationship between viewing a digital file on a screen and the size of a physical print, no matter what zoom level you view at. It doesn't matter how many pixels your monitor has per inch of physical screen.... your printer doesn't know or care.

Digital pixels don't equal dots of ink. Physical print size is defined by the number of dots of ink per inch deposited by the printer onto a sheet of paper. This is controlled by the printer driver/software and is unrelated to the number of pixels on your monitor screen. If you have a digital image that is 3,000 pixels wide and you zoom in to 1:1 and then print the image at 1,000 dots per inch the print will be 3" wide. If you print it at 100 dots per inch it will be 30" wide.

Dan Marchant wrote in post #18155437
Your question has no meaningful answer because there is no relationship between viewing a digital file on a screen and the size of a physical print, no matter what zoom level you view at. It doesn't matter how many pixels your monitor has per inch of physical screen.... your printer doesn't know or care.

Digital pixels don't equal dots of ink. Physical print size is defined by the number of dots of ink per inch deposited by the printer onto a sheet of paper. This is controlled by the printer driver/software and is unrelated to the number of pixels on your monitor screen. If you have a digital image that is 3,000 pixels wide and you zoom in to 1:1 and then print the image at 1,000 dots per inch the print will be 3" wide. If you print it at 100 dots per inch it will be 30" wide.

Great, detailed answer, and true. But the OP is asking what size PRINT would be the same size as 1:1 on his screen. Post #3 provides one answer. The answer for the OP depends on: camera used, and screen size/resolution.

Even so I stand by my answer. Zooming in to 1:1 will tell the OP nothing meaningful about the physical print size of an image and their monitor is irrelevant/meaningless​. To explain.....

A full size (uncropped) Rebel T6 RAW file is 5184 x 3456 pixels.

The default DPI setting for printers varies a bit but is around 600 dots per inch.

A fairly high spec Dell 27" (wide viewable image size) monitor has an optimal resolution of 2560 x 1440 which is 94.8 pixels per inch.

If the OP zooms in to 1:1 the vast majority of the image will be off screen. All he will see is a 2560 x 1440 section of the image. The "size"of the digital image viewed in this way is approx 54" but how is that helping when the OP presses Print and the image comes out of the printer at 30" (or 3" or any other size depending on what number then select in the print driver).

The only info the OP needs to know to calculate the size of the print is the pixel dimensions of the image file and the DPI of the printer. The monitor is irrelevant and unnecessary.

5184 / 600 = 8.64"
3456 / 600 = 5.76"
It is a 9x6" print.

Change the DPI setting in the printer or the pixel size of the image file and the size will change regardless of what monitor you have or how you zoom into the image.

Dan Marchant wrote in post #18155437
Your question has no meaningful answer because there is no relationship between viewing a digital file on a screen and the size of a physical print, no matter what zoom level you view at. It doesn't matter how many pixels your monitor has per inch of physical screen.... your printer doesn't know or care.

...The only info the OP needs to know to calculate the size of the print is the pixel dimensions of the image file and the DPI of the printer. The monitor is irrelevant and unnecessary..

Since OP failed to mention his screen resolution and horizontal size, we'll have to speak hypothetically...I have a 2560 horizontal resolution screen across 23.25". Let us assume I use a 5DIII, which is 5760 pixels horizontal.
So at 1:1 (100%) I would be seeing 2560/5760 or 44.44% of the image fit into a 23.25" space. So if I extrapolate, 23.25"/0.4444 = 52.32" full image if he had a monitor with that many pixels at a comparable pixel pitch.

As for printing, a printer's DPI value is meaningless. The ONLY thing that matters is that the software says 'Spread 5760 pixels across a print which is X" horizontally.' And that print size you control, which then (indirectly) determines the PPI value of that particular print.

This is so easy to see approximately. All you need is a ruler and very minimal math. Photograph the ruler (0-12) so it just fills your frame horizontally. Display it at 1:1 (100%) and scroll to the left side. What number appears on the right side? Let's say 3. So you are looking at a quarter of the image's horizontal dimension.

Now take the ruler and measure your monitor. Let's say 20 inches. So you are looking at the rough equivalent of an 80 inch print. Get up out of your chair and back up to the far wall, because nobody (but Chauncey) looks at an 80 inch print from computer work distance.

I say "rough equivalent" because the digital image on its way to the print paper will very likely be resampled - by you, by the OS, by the driver or by the RIP - but an image displayed electronically at 1:1 is not resampled. At "across the room" print viewing distance, you will probably not see the artifacts left by the resampling.

To add to what others have already said:

I assume that in LR at 1:1 (100%) view LR displays 1 image pixel to 1 screen pixel.

Therefore the number of pixels displayed will depend on the size of the current window, if in Fullscreen Mode then the number of pixels displayed will be the same as the monitor. The physical size of the image will depend on the dimensions of the monitor.

When printing you can define how many pixels to use per inch and what size paper to use, the image is re-sampled as required.

To create a print that size for size is same size as displayed on the monitor I expect you would have to calculate the resolution of your monitor and then ensure you print at the same resolution - however, this will not produce a quality print as on average monitors are around 100ppi resolution and good prints are expected to be around 300ppi. Quality of print and print resolution depends on several factors such as paper type, dpi of printer etc.

From this I would deduce that if one prints the image cropped to match what is currently displayed on the screen and at the ideal printer resolution of say 300ppi the print would be approx. 1/3rd the physical size of what is displayed on the monitor.

In conclusion the relationship between a 1:1 monitor image and print size will depend on what resolution you send the image to the printer at. For print to be same size as physically displayed on the monitor you need to calculate your screen resolution in ppi and ensure that you send the image to the printer at the same ppi setting.

HTH