How to measure artwork for custom picture frames
Written by: Daniel Koren, Co-Founder, Frameology
Key takeaways
Use a rigid metal ruler, measure artwork width first, then height, and record to the nearest 1/16 inch for an accurate custom frame fit.
Measure only the artwork itself, not existing mats, frames, or stretcher bar labels, because small errors can cause gaps or buckling.
For matted pieces, remember the frame size equals artwork size plus twice the mat border width on each dimension to prevent ordering mistakes.
Canvas needs stretcher bar depth measurements and the multi-point method to account for warping or bowing before you order a floating or standard frame.
How to measure art for a frame at home
Accurate framing starts with the right tools and a simple setup. A rigid ruler or measuring tape works better than a flexible fabric tape, which can stretch and throw off the cut of the frame, backing, and acrylic. A metal ruler gives the most reliable results.
Keep these basics in mind before you measure:
Place the artwork on a flat, well-lit surface in the orientation it will be displayed, portrait or landscape, so you measure it exactly as it will appear on the wall.
Measure to the nearest 1/8 inch at minimum, and for the tightest fit, work to the nearest 1/16 inch, since that level of precision prevents fit issues later.
Always record dimensions as Width × Height, with width listed first, so you avoid mixing up the numbers when you order.
Measure the artwork itself, not an old frame it lived in, because frame dimensions rarely match the true artwork size.
Professional framers work in fractions of inches because small measurement errors can quickly compound and cause visible gaps, buckling, or installation problems.
If your artwork is close to a standard size such as 5×7, 8×10, 11×14, 16×20, or 18×24, check whether it falls within 1/4 inch of that size. Standard sizing often costs less and is easier to find.
How to size a flat picture for a frame
Flat paper artwork such as photos, fine art prints, and posters is the simplest to measure, but a few rules still matter. You want the frame to fit the paper, not just the image area.
Measure only the artwork itself from left edge to right edge for width and top edge to bottom edge for height. Don’t include any existing mat or frame in that number. The dimension you record is the artwork size, and that’s what you’ll enter when you order a custom frame.
Use these extra guidelines for flat paper pieces:
Don’t round up on artwork size, because even a small increase can cause the mat to sit incorrectly or the print to buckle.
Confirm orientation before ordering, and double-check whether the piece is portrait or landscape, since a swapped width and height will give you a frame that’s rotated 90 degrees from what you wanted.
Check the aspect ratio, because mismatched ratios are the main reason prints don’t fit frames. A 4:5 print such as an 8×10 won’t fit a 2:3 frame such as a 16×24 without cropping or visible gaps.
How much bigger the frame should be than the poster
The frame usually needs to be larger than the poster, and the exact difference depends on whether you’re adding a mat and what type of artwork you’re framing. Flat posters follow one set of rules, while stretched canvas needs a different approach because of its depth.
For stretched canvas, measure the outer dimensions of the stretcher bars rather than the visible painted area, and record width, height, and depth to the nearest 1/16 inch. The depth matters because it determines whether you need a standard frame or a floating frame. Standard canvas stretcher bar profiles usually range from 0.75 inches to 1.5 inches deep, while gallery-wrap canvases typically measure 1.25 to 2 inches deep.
Use the multi-point method for canvas for more accurate results:
Measure width at the top and bottom of the canvas front face, then use the smaller of the two readings.
Measure height at the left and right sides, then use the smaller reading.
Measure depth from the front surface to the farthest back edge of the stretcher bars.
Allow one-eighth inch clearance around the canvas perimeter for floating frames to handle slight variations and allow easy insertion.
Nominal labels such as “16×20” often don’t match the actual stretched dimensions, so always measure the physical piece instead of trusting the label on the back.
For flat posters without a mat, the frame opening should match the poster size exactly. Professional frames include a rabbet that overlaps the print edge by about half an inch, which holds the piece securely without covering the image. The outer frame dimensions will always be larger than the artwork itself because they include the molding profile.
How to measure matted artwork window and outer frame size
Mats add an extra layer of measurements, so clarity here prevents many ordering mistakes. You’ll work with three numbers: the artwork size, the mat window, and the outer frame size.
When a mat is involved, there are three distinct measurements to understand: the artwork size, the mat window opening, and the outer frame size. Mixing these up is one of the most common ordering errors.
The mat opening should be 1/4 inch smaller than the artwork on each side, so the mat overlaps the image edge and holds the piece in place without letting the artwork fall through. This creates a 0.25-inch overlap on each side, which stays invisible while keeping the piece secure.
To calculate the outer frame size, use this formula: Frame Size = Artwork Size + (2 × Mat Border Width). Here’s how that works at common sizes:
An 8×10 print with a 2-inch mat border needs a 12×14 frame.
An 11×14 print with a 2.5-inch mat border needs a 16×19 frame, often rounded to 16×20.
An 18×24 print with a 3-inch mat border needs a 24×30 frame.
Current mat-sizing guidelines suggest 2-inch borders for artwork up to 8×10, 2.5–3 inches for 11×14 to 16×20 pieces, and 3–4 inches or more for larger works. Many galleries slightly weight the bottom mat border by making it about 1/2 inch wider than the top and sides, which corrects the optical illusion that equal borders make artwork appear to sink in the frame.
How to measure already-framed pieces
Already-framed artwork needs a different reference point than bare artwork. You’ll either match the existing frame opening or plan for the full footprint on the wall.
When you measure already-framed artwork to replicate the size, measure from the inside edge to inside edge of the existing frame instead of the outer frame dimensions. The inner dimension is the artwork size the new frame needs to hold.
If you’re planning wall space or shipping the piece, measure the finished outer frame dimensions from leftmost to rightmost edge, top to bottom, and front to back. For an already-framed canvas, measure the inner canvas support itself when you replace artwork or order a floating frame.
Use this quick checklist for already-framed pieces:
Inner dimension, or artwork size: measure from inside rabbet edge to inside rabbet edge on both axes.
Outer dimension, or wall footprint: measure the full frame from outermost edge to outermost edge.
Depth: measure front to back to confirm the new frame’s rabbet depth can hold the artwork.
Rounding and recording measurement best practices
Once you’ve taken your measurements, how you record and round them matters just as much as the measuring itself. Clear notes prevent confusion at checkout.
Record to the nearest 1/16 inch for the tightest fit, since even a 1/8-inch error can make custom frames fit poorly or require replacements.
Never round up on artwork dimensions, and instead round down or stay exact so you don’t end up with a frame that’s too small.
Always label orientation explicitly as Width × Height so there’s no ambiguity when you enter the numbers online.
Measure twice and record once, and confirm both readings match before you write anything down.
Note the artwork type alongside the dimensions, such as flat paper, stretched canvas, or matted, so you enter the right measurement type when you order.
Keep a written record that includes Width × Height, artwork type, mat border width if needed, and canvas depth if needed, which covers everything you’ll need at checkout.
Common measuring challenges and how to fix them
Even with careful measuring, some situations can complicate the process. A few small adjustments help you handle the most common issues.
Odd or non-standard sizes: If your artwork doesn’t match a standard size, resist the urge to force it into one. Enter the actual measured dimensions when you order a custom frame. For non-rectangular artwork such as oval or circular pieces, measure the widest horizontal point and the tallest vertical point to find the required frame size.
Warped or bowed canvas: Irregular or warped surfaces need more than one reading. Measure at three points for both width and height instead of relying on a single measurement, because bowing often creates uneven numbers. Use the smallest width reading and the largest height reading so the frame can hold the full piece. For slightly warped artwork, gently flatten it on a hard surface, measure as if flat, and note the warping when you order.
Mat border math errors: Many people forget that the mat border adds to both dimensions twice, once on each side. A 2-inch border adds 4 inches to the width and 4 inches to the height. Always apply the formula Frame Size = Artwork Size + (2 × Mat Border Width) to both dimensions separately before you order.
Oversized artwork: For artwork over 24×36 inches, use a long measuring tape or ruler, ask someone to help hold the piece flat, and measure from a clear corner reference point while you double-check all measurements.
Trusting the label instead of measuring: Nominal size labels on canvas, posters, and prints often miss the mark. Always measure the physical piece instead of relying on stated sizes from artists or sellers.
Frequently asked questions
What drives the cost of a custom frame?
The main cost factors are frame size, material tier, and whether a mat is included. Larger frames use more material and need more precise cutting, which raises the price. The material tier also matters, since Classic frames use quality materials at an accessible price point, while Luxe frames use premium wood molding and metal moldings, acid-free mats, and UV-protecting museum-grade acrylic. Adding a mat increases the outer frame size, which can change pricing. Getting your measurements right the first time helps you avoid the cost of reordering due to sizing errors.
What image resolution do I need for a well-printed custom frame?
For sharp, gallery-quality results, aim for a minimum of 300 DPI, or dots per inch, at the intended print size. A file that looks crisp on a phone screen may print with visible pixelation at 16×20 or larger. If you’re printing from a smartphone photo, recent flagship phones usually produce files large enough for prints up to 16×20 at 300 DPI. For larger prints, a DSLR, or digital single-lens reflex camera, or a mirrorless camera file works best. Frameology uses continuous-tone archival printing on premium photo paper for framed prints, so the printing technology can render fine detail if the source file supports it.
How do I adapt my measurements if the artwork is going on a very large or very small wall?
The artwork measurements themselves stay the same regardless of wall size, since you’re always measuring the physical piece. What changes is the mat border width and frame size you choose relative to the wall. A large wall can support a wider mat border and a larger outer frame, which makes the piece feel intentional instead of lost. A small wall usually looks better with a tighter mat or no mat at all. A useful rule of thumb: the framed piece should occupy roughly 57–75% of the wall width it hangs on. Measure the wall, calculate that range, and work backward to find the right mat border width for your artwork size.
Do light and humidity affect framed artwork, and should I account for that when measuring?
Light and humidity affect the artwork inside the frame, not the measurement process itself, but they still matter when you choose your frame. UV-protecting museum-grade acrylic, included in every Luxe frame, blocks harmful ultraviolet light that causes fading and color shift over time. Humidity can cause paper-based artwork to expand and contract slightly, which is why acid-free mats and a proper 1/4-inch overlap on each side are standard practice. They hold the piece securely while allowing minor movement without buckling. For high-humidity rooms such as bathrooms or kitchens, frameless options like an HD Metal Print resist moisture better than paper-based framed prints.
What’s the biggest risk when measuring artwork at home, and how do I avoid it?
The biggest risk is measuring the wrong thing, such as the old frame instead of the artwork, or the painted face of a canvas instead of the stretcher bar edges. The second most common risk is measuring only once and trusting a single reading on a surface that’s slightly warped or uneven. Both are easy to avoid when you follow a few habits. Always measure the artwork itself, not the frame it came in, use a rigid metal ruler on a flat surface, and measure at least twice at different points across the piece. Record dimensions as Width × Height, note the artwork type, and confirm the numbers before you order.
