Frame sizes from the artwork out, gallery spacing from the wall in
Framing is a chain of sizes, each one derived from the last, and an error at any link shows at the glass. Mode 1 walks the chain: artwork, mat opening and board, glass, frame outside, and the moulding cut list, with the overlap that holds the artwork under the mat stated as an input rather than hidden in the math. Mode 2 does the wall: given a span and a row of equal frames, it computes the equal gaps and prints the mounting coordinates, where each frame’s left edge and centre fall, plus the top and bottom marks when you give a hanging centre height, so the level and the tape measure agree before any hole is drilled.
Mode 1: the frame build
Mode 2: spacing a row on a wall
Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. Sizes assume square, true materials; check moulding and board stock against the cut list before cutting, and mark walls from the coordinates before drilling.
What this calculator does
Mode 1 derives the full size chain of a framed piece from the artwork outward. The mat opening is the artwork shrunk by the overlap on every side, because the mat must grip the edges it hides. The mat board’s outside is the artwork grown by the border on every side (with no mat, the board step drops away and the artwork itself is what the frame holds). Glass is cut to the board’s size, which is also the frame’s inside (rabbet-to-rabbet) size. The frame’s outside adds the moulding width on every side, and the cut list gives the four moulding pieces by their long-point (outside) lengths, two of each dimension, to be mitred at 45 degrees. Mode 2 divides a wall span by the equal-gap rule: the leftover after the frames is shared by one more gap than there are frames, counting the ends, and every frame’s left edge and centre are listed as distances from the left of the span, with top and bottom heights from the centre height when the frame height is given.
How to use it
- Measure the artwork, not its packaging. Prints ship with white borders that may or may not be part of the piece. Decide what is image and measure that; a border kept is part of the artwork, a border trimmed is not, and the mat opening follows the decision, not the shipping tube.
- The overlap is small and structural. Too little and the artwork slips or shows its edge against the opening; too much and it eats composition. A quarter inch per side is the standard for a reason, and works of value on paper are usually hinged so the overlap never touches image.
- Order the chain in the shop’s order. Cut list first (moulding by long point), then board and glass to the inside size, then assemble. The mode prints all three sizes because each is a separate purchase or cut, and a framer’s counter runs on exactly these three numbers plus the opening.
- Frame width in Mode 2 is the outside. Spacing works on the physical object, frame edge to frame edge, so use Mode 1’s outside width for the frames being hung, not the artwork size. Gaps measured between artworks while frames vary is how gallery walls drift out of rhythm.
- Mark centres, hang by them. The coordinates give centres because hanging hardware works from the centre (wire apex or D-ring midpoint rarely sits at the frame’s top). Measure the hardware’s drop from the top of each frame, apply it to the top mark, and the centres stay true even when hardware differs per frame.
How it is calculated
- Mat opening = artwork – 2 x overlap, per dimension. Mat board / glass / frame inside = artwork + 2 x mat border (or the artwork itself when the border is 0). Frame outside = inside + 2 x moulding width. Cut list: two pieces at the outside width and two at the outside height, mitred, lengths measured at the long point.
- Equal gaps: gap = (wall span – number of frames x frame width) / (frames + 1). Frame k’s left edge = gap x k + frame width x (k – 1); its centre adds half the frame width. Heights: top = centre height + frame height / 2; bottom = centre height – frame height / 2.
Worked examples
An 8 x 10 print, matted and framed. Mat border 2 inches, overlap a quarter inch, moulding 1.5 inches. The mat opening is 7.50 x 9.50, the board and glass are 12.00 x 14.00, the frame outside is 15.00 x 17.00, and the saw list is two pieces at 17.00 and two at 15.00, long point. Every number a frame shop would quote is on that line, each one a single stated step from the last.
Three frames on a 10 foot wall. Span 120 inches, three frames of 20 inches outside width. Leftover: 60 inches over four gaps: 15.00 inches each. Left edges fall at 15.00, 50.00 and 85.00; centres at 25.00, 60.00 and 95.00, the middle frame centred on the wall’s own centre, as even spacing guarantees. At the standard 57 inch centre height with 24 inch frames, the tops mark at 69.00 and the bottoms at 45.00 inches from the floor.
Reading your results
In Mode 1, sanity-check the chain by its growth: opening smaller than artwork, board larger, frame larger again; any step out of order means an input is wrong, most often a border entered where an overlap was meant. In Mode 2, check that the last frame’s right edge plus one gap lands exactly on the span’s end; the list is built so it must, and a tape measure on the wall should reproduce the centres to the pencil line’s width. If it does not, the span was measured to a different edge than the row will use.
Limitations
- Moulding profiles vary in what “width” means. The cut list uses face width and outside dimensions; deep or scooped profiles are measured at their widest point for the outside size, and the rabbet depth (which governs how thick a package the frame accepts) is a separate specification this page does not model. Stack thickness (glass, mat, artwork, backing) must fit the frame’s rabbet; check the moulding’s stated capacity when building up layers.
- Equal frames only, in Mode 2. Mixed-size groupings are a composition exercise with no single formula; the standard method is to lay the arrangement on the floor or in paper templates and transfer the coordinates, which this mode cannot do for you. What transfers: the centre-height discipline and the habit of working from centres.
- Bottom-weighted mats are a deliberate exception. Traditional framing gives the bottom border extra depth for optical balance. This page’s borders are equal per the inputs; for a bottom-weighted mat, enter the side/top border here and add the extra to the board’s height manually, cutting the opening off-centre by the same amount.
- Walls and floors are not instruments. Spans measured along a skirting board or a sloping floor inherit its errors; measure the span at hanging height, and level from a laser or a long level rather than from the floor or ceiling line, which in real rooms may be the least level things in them.
Frequently asked questions
What size frame do I need for an 8 x 10 photo?
It depends on the mat, which is the point of the chain: unmatted, an 8 x 10 takes an 8 x 10 frame (inside size), and the outside is that plus twice the moulding width. Matted with a 2 inch border, the inside size becomes 12 x 14, the commonest shop combination, and a 1.5 inch moulding makes the outside 15 x 17 with a mat opening of 7.5 x 9.5 at the standard quarter-inch overlap. Mode 1 prints the whole chain for your moulding so the frame ordered and the glass cut agree.
How do I space pictures evenly on a wall?
Give the gaps, including the two ends, equal shares of what the frames leave: subtract the frames’ total width from the span and divide by one more than the number of frames. Three 20 inch frames on a 120 inch span leave 60 inches for four gaps of 15. Mark each frame’s centre from the coordinates Mode 2 prints (25, 60, 95 there), hang by the centres, and the ends come out equal by construction rather than by eye and adjustment.
How high should pictures hang?
The gallery convention centres the piece at 57 inches from the floor, roughly average eye level, which Mode 2 uses as its default centre height. Over furniture the rule changes to relationship: the frame’s bottom 6 to 8 inches above the piece it hangs over reads connected rather than stranded, so enter the centre that results (furniture height plus the gap plus half the frame). In stairwells and halls of tall people both conventions bend; the centre-height input is there to be set by the room, not obeyed from the page.
What is the long point of a moulding cut?
A mitred piece has a long edge (the outside corner) and a short edge (the inside). Cut lists are given in long-point lengths: the full outside dimension of the finished frame, 17.00 and 15.00 in the worked example, because two long points meet to form the outside corner exactly. Cutting to the short point or the middle of the mitre is the classic first-frame error, shrinking the frame by the mitre’s diagonal at every corner; the cut list here is unambiguous on purpose.
Related calculators
Method: the framing size chain (opening, board, glass, outside, long-point cut list) from artwork dimensions with stated overlap and border, and equal-gap gallery spacing with centre-based mounting coordinates, exactly as defined on this page. Last reviewed: 13 October 2026.