# Picture Frame Calculator

URL: https://speedycalculator.com/calculators/everyday-life/picture-frame/
Last updated: 2026-10-25

> The picture frame calculator works out the glass (glazing) size, the outside frame size and the length of moulding to buy for a picture with a mat border, allowing for the rabbet and a small fitting allowance.

## Inputs

- Picture width (in, cm)
- Picture height (in, cm)
- Mat border width (in, cm)
- Moulding (frame) width (in, cm)
- Rabbet width (in, cm)
- Fudge allowance (in, mm)
- Waste for mitres (%)

## Results

- Mat outer width
- Mat outer height
- Glass width
- Glass height
- Outer frame width
- Outer frame height
- Moulding to buy

## Formula

```
Opening = picture + 2 × mat border
Glass = opening + 2 × rabbet − fudge
Outer frame = opening + 2 × moulding width
Moulding length = 2 × (outer width + outer height) + waste for the four mitres
```

## Explanation

A framed picture usually sits behind a mat that overlaps the artwork by about ¼ in on each side. The frame's rabbet (the lip that holds the glass) hides the edge of the glass and mat, so the glass is cut a little smaller than the rabbet size – about ⅛ in – so it drops in easily.

### How to use the Picture Frame Calculator

- **Picture width**
- **Picture height**
- **Mat border width**
- **Moulding (frame) width**
- **Rabbet width**
- **Fudge allowance**
- **Waste for mitres**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the picture size, mat border width, moulding width, rabbet depth and fudge allowance.

### Tips

- Use the figures printed on your product or its manual when you have them.
- Round quantities up so you are never short.
- Measure twice before you buy anything cut to size.
- Everything runs in your browser – try different values to compare options.

### Common mistakes to avoid

- Mixing units (inches and centimetres, mAh and Ah).
- Ignoring efficiency losses and safety margins.
- Treating rules of thumb as exact.

### Inputs explained

FieldWhat to enterPicture widthUnits: in, cmPicture heightUnits: in, cmMat border widthUnits: in, cmMoulding (frame) widthUnits: in, cmRabbet widthUnits: in, cmFudge allowanceUnits: in, mmWaste for mitresIn %

### What each result means

- **Mat outer width** = [Picture width] + 2×[Mat border width]
- **Mat outer height** = [Picture height] + 2×[Mat border width]
- **Glass width** = [Mat outer width] - [Fudge allowance]
- **Glass height** = [Mat outer height] - [Fudge allowance]
- **Outer frame width** = [Mat outer width] + 2×([Moulding (frame) width] - [Rabbet width])
- **Outer frame height** = [Mat outer height] + 2×([Moulding (frame) width] - [Rabbet width])
- **Moulding to buy** = 2×([Outer frame width] + [Outer frame height])×(1 + [Waste for mitres]÷100)

### Example values

How the main result changes when **Picture width** changes and everything else stays at the example values above:

Picture width (in)Moulding to buy (in)459.4663.8868.21072.612771685.8

## Worked example

Inputs — Picture width: 8 in; Picture height: 10 in; Mat border width: 2 in; Moulding (frame) width: 1.5 in; Rabbet width: 0.25 in; Fudge allowance: 0.125 in; Waste for mitres: 10 %.

Results — Mat outer width = 12 in; Mat outer height = 14 in; Glass width = 11.875 in; Glass height = 13.875 in; Outer frame width = 14.5 in; Outer frame height = 16.5 in; **Moulding to buy = 68.2 in**.

## FAQ

**How much moulding do I need for a frame?**
The outer perimeter of the frame plus about 10% for the four 45° mitre cuts.

**How much should a mat overlap the picture?**
About ⅛–¼ in on each side so the artwork doesn't fall through.

**What is a rabbet?**
The recess on the back of a frame that holds the glass, mat and backing.

**What formula does the Picture Frame Calculator use?**
Opening = picture + 2 × mat border.