写真フレームの測り方（作品寸法と額縁寸法）
額縁の規格サイズは外寸ではなく、ガラスや裏板が収まる「内寸」を指します。
⚡写真フレームの測り方（作品寸法と額縁寸法） Calculator
Live Interactive写真フレームの測り方（作品寸法と額縁寸法） — Step-by-Step Reference
ポスターや写真に合う額縁サイズの測り方。マット窓寸とフレーム内寸の計算機。
US Imperial Standard
Standard fractions divided into 1/16", 1/8", 1/4", and 1/2" increments with exact decimal benchmarks.
Metric SI Equivalence
Millimeter and centimeter precision calculated using exact 25.40 mm per international inch conversion.
写真フレームの測り方（作品寸法と額縁寸法） FAQ
How do I measure a picture frame size?
Frame size is the size of the artwork or photo the frame holds, given as width by height in inches. Measure the opening (the visible area behind the glass) rather than the outside edge of the frame.
What does 11x14 mean for a picture frame?
It means the frame holds an 11 inch wide by 14 inch tall print or mat. With a mat, an 11x14 frame commonly displays an 8x10 photo.
What are standard picture frame sizes?
Common US sizes are 4x6, 5x7, 8x10, 11x14, 16x20, 18x24 and 24x36 inches. See the reference table above.
How big should the mat opening be?
The mat opening is usually about 1/4 inch smaller than the photo in each direction, so the mat overlaps the photo by about 1/8 inch per side. The calculator above shows the photo, mat and final glass size.
How do I figure out my frame size with a mat?
Add the mat border to both sides of the visible photo area. For example, an 8x10 photo with a 1.5 inch mat border on every side needs an 11x13 outer mat size, so choose a frame that matches that size.
Is 20x26 a standard frame size?
It is not among the most common ready-made sizes, so it is often custom. 20x24 and 20x30 are easier to find.