This calculator is designed for input and output in inches with fractional parts down to 16ths of an inch. It is still a work in progress and there are no guarantees of its usefullness or accuracy. I developed this to make my life easier when framing my own pictures. It is designed for completely custom framing. If you are trying to print and matte to a standard frame size, it will take some trial and error with the dimensions to get it to come out right.
The "Input Data" section is where you enter the basic data for the width and height of the image that you are framing. The other needed information is the width of the frame material you will be using and the depth of the recess in the frame. You can clear all the fields to start over at any time by clicking on the "Clear" button.
In the "Default Data" section you can set the amount of overlap of the matte over the image. The default value is 1/8 in. That allows a little slop when aligning the matte over the picture when assembling the whole thing. You can make this bigger or smaller as needed. If you want to have exposed paper around the image, you will need to manually add that amount to the image size when entering that data. There are defaults for the matte border width around the image. This is set up so that the bottom width can be different than the top and sides. Generally, it is desirable to slightly enlarge the bottom matte area for esthetic reasons. This creates a more "balanced" look when the picture is on display. There are also provisions for double matting if so desired. If you are only using a single matte, you can ignore the second matte dimension. There is a setting for the recess between the top matte and the bottom matte. If you change the recess number, it will recalculate the second matte width when you click on the Apply button. If you change the primary matte Top/Side width, it will automatically recalculate the Bottom width at about 1.12 times the Top/Side value. If you change the Bottom matte width or secondary matte widths manually, the new values will override the calculations. You can get back to the defaults at any time by clicking on the "Defaults" button.
The suggested border button will calculate a matte border that is based on the picture dimensions. It strives to create a border that is designed to be esthetically pleasing ratio of 1.618 of total area to picture area. This also means that the picture area to matte area is the same ratio. It adds the Rabbet Recess value to the calculated border width so that the exposed matte area is what is used in the calculations. At this time it is just a suggestion and does not enter into any of the other calculations. If you want to use the suggested value, you will have to enter it manually. I may eventually make it use the calculated value as the default border width.
In the "Output Data" section when you click on the "Calculate" button, the program uses the above input and default data to calculate the overall matte and frame dimensions. It adds 1/8th inch around the matte(s) to the frame to allow ease of assembly. If you are using glass, the glass should be cut to the same size as the matte(s). The overall frame dimensions are the outside dimensions and are predicated on using 45° miter joints. The total frame size indicates how much framing material you will need not accounting for waste.
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