United Inch Pricing Explained: How Framers Price Mats and Glass

Walk into almost any custom frame shop in the English-speaking world and ask how the mat and glass are priced, and you will hear the same two words: united inches. It sounds technical, but it is one of the simplest ideas in the trade. Once you understand it, the price of a framed piece stops being a mystery and becomes something you can estimate in your head before the framer ever opens a price book.

This post explains the united inch method from the ground up — what the number means, why framers reach for it instead of square inches, how price charts are built, and where it quietly breaks down. Whether you are a new framer learning to quote or a customer trying to understand an invoice, by the end you will be able to calculate united inches for any piece and reason about what it should cost.

What Is a United Inch?

A united inch is the sum of an item’s two dimensions — width plus height — expressed as a single number.

That is the whole definition. There is no multiplication, no area, no square roots. You take the width, you take the height, and you add them together.

• An 11 × 14 inch piece is 11 + 14 = 25 united inches.
• A 16 × 20 inch piece is 16 + 20 = 36 united inches.
• A 24 × 36 inch piece is 24 + 36 = 60 united inches.

People sometimes abbreviate united inches as “UI” on worksheets and price charts. You will also see the phrase “combined inches” used interchangeably; they mean the same thing. The concept maps directly to centimetres too — united centimetres is width plus height in centimetres — so the method is not tied to imperial units. It is simply a way of reducing a two-dimensional size to one tidy index.

The important thing to grasp is what the number is measuring. It is not the area, and it is not the perimeter. It is a proxy — a single value that grows as a piece gets bigger and correlates well enough with both perimeter and area to be useful for pricing. Why that proxy works, and where it stops working, is the heart of this post.

Why Framers Use United Inches Instead of Square Inches

A framed piece is built from materials that scale in different ways. Understanding those differences explains why one simple number does so much work at the counter.

The three ways materials scale

When you frame something, the cost is driven by three different geometries:

• Moulding scales with perimeter. You buy frame moulding by the foot and cut four lengths to surround the artwork (plus mat borders). The total footage you consume is governed by the distance around the outside — the perimeter. Perimeter is 2 × (width + height), which is exactly twice the united inches. So united inches are directly, linearly proportional to the frame’s perimeter. This is the cleanest relationship of the three.
• Glass and backing scale with area. A sheet of glazing covers the whole opening, so its material cost tracks the area — width × height. Mat board, backing board, and foam core are also area-based: they are cut from large sheets, and a bigger opening eats more sheet.
• Labour scales with a mix of both. Cutting a longer mat opening or chopping longer moulding takes more time (perimeter-ish), but handling a large, heavy sheet of glass and fitting a big frame also takes more time (size-ish). Labour is messy and does not follow either geometry perfectly.

So why not just price glass and mat by true square inches and moulding by the foot? Two reasons: speed and consistency at the counter.

Speed and simplicity

A united inch is a sum. A framer can compute it instantly, in their head, for any size a customer names. Square inches require multiplication and produce awkward numbers — an 18 × 24 piece is 432 square inches, which is hard to look up and harder to reason about. United inches give you small, memorable numbers (25, 36, 60) that slot neatly into a price chart.

That speed matters because framing is a high-touch, conversational sale. The customer is standing there with their photograph or print, asking “roughly what will this cost?” The framer wants to give a confident, quick range without disappearing into a calculator. United inches let them do that.

It builds clean price tiers

Because united inches grow smoothly with size, you can build a price ladder with sensible breakpoints: a band for pieces up to 24 UI, another up to 36 UI, another up to 48 UI, and so on. Each band has a single price for mat, a single price for glass, and often a labour figure baked in. Look up the band, read across, done. We will build one of these charts in a moment.

It is a deliberate approximation

The honest framing of all this is that united inches are an approximation, and a clever one. They are exact for perimeter (and therefore excellent for moulding) and a reasonable stand-in for area across common picture sizes — but they are not the true area. You accept a little inaccuracy on area-based materials in exchange for large gains in speed and consistency. For most shops, on most jobs, that trade is well worth it. The exceptions — long, skinny pieces and very large pieces — are exactly the pitfalls we cover later.

How United Inch Price Charts Work

A united inch price chart is a lookup table. The framer measures the piece, calculates a single united inch number, and reads the corresponding price for each component. Here is a simplified, illustrative chart. The numbers below are examples only — every shop sets its own rates based on its costs, region, and target margin.

Two design choices are worth noticing.

First, the bands are tiered by ceiling: a 30 UI piece falls into the “up to 36 UI” row and pays the 36 UI rate. This deliberately rounds up, which protects the shop’s margin and keeps the chart short. A few shops instead price by exact united inch using a per-UI rate — for instance, “$0.95 per united inch for standard mat” — which gives a smooth curve with no jumps. Both approaches are common; tiered charts are faster to read, per-UI rates are more granular.

Second, labour is often bundled into the band rather than billed separately. Cutting a mat, cutting glass, joining the frame, and fitting everything together all take longer on a bigger piece, so it is natural to let those costs ride along on the same size ladder. Some shops break labour out as its own line so the customer can see it; others fold it into the mat and glass prices. There is no single correct convention — only the one your shop applies consistently.

Building a tier from your real costs

If you are setting up your own chart, the logic for each band is the same:

1. Take the largest size in the band (the ceiling).
2. Work out the material the band’s ceiling consumes — square inches of mat and glass for that size — and multiply by your cost per square inch, including waste.
3. Add the labour time for that band at your shop rate.
4. Apply your markup.

Because you size each band to its ceiling, smaller pieces in the band carry a little extra margin, which offsets the awkward in-between sizes and the occasional underestimate. That built-in cushion is part of why tiered united inch pricing is forgiving.

Worked Examples: Watching the Number Drive the Quote

Let us price three common sizes using the illustrative chart above, with conservation glass and a single standard mat. We will also add a moulding cost so the examples feel like real quotes. Assume the moulding is $6.00 per foot, and the mat adds a 2-inch border on all sides (more on borders shortly).

Example 1: 11 × 14 print (25 united inches)

• United inches of the artwork: 11 + 14 = 25 UI. That lands in the “up to 36 UI” band (it is over 24).
• Mat: $26.
• Conservation glass: $46.
• Labour: $26.
• Moulding: With a 2-inch mat border, the framed outer size becomes 15 × 18 inches. Perimeter is 2 × (15 + 18) = 66 inches = 5.5 feet. At $6/ft that is $33.
• Subtotal: 26 + 46 + 26 + 33 = $131, before markup, minimum, and tax.

Example 2: 16 × 20 print (36 united inches)

• United inches of the artwork: 16 + 20 = 36 UI. This sits right at the top of the “up to 36 UI” band.
• Mat: $26.
• Conservation glass: $46.
• Labour: $26.
• Moulding: With the 2-inch border, outer size is 20 × 24 inches. Perimeter is 2 × (20 + 24) = 88 inches = 7.33 feet. At $6/ft that is $44.
• Subtotal: 26 + 46 + 26 + 44 = $142.

Notice that the 11 × 14 and 16 × 20 pieces fall in the same mat and glass band even though the 16 × 20 has noticeably more area. That is the tier rounding at work — the smaller piece subsidises the larger one within the band, and the only thing that changed between the two quotes was the moulding footage.

Example 3: 24 × 36 poster (60 united inches)

• United inches of the artwork: 24 + 36 = 60 UI. This lands in the “up to 60 UI” band.
• Mat: $48.
• Conservation glass: $92.
• Labour: $44.
• Moulding: With the 2-inch border, outer size is 28 × 40 inches. Perimeter is 2 × (28 + 40) = 136 inches = 11.33 feet. At $6/ft that is $68.
• Subtotal: 48 + 92 + 44 + 68 = $252.

The poster’s quote nearly doubles the 16 × 20, which feels right: it is a much bigger object in every dimension.

Contrast: what true square-inch glass would say

Let us sanity-check the glass line against true area, since glass is the most area-driven component.

• 11 × 14: 154 square inches.
• 16 × 20: 320 square inches.
• 24 × 36: 864 square inches.

The 16 × 20 has roughly 2.1 times the glass area of the 11 × 14, yet the united inch chart put them in the same glass band ($46 each). The 24 × 36 has 5.6 times the area of the 11 × 14 but only about twice the glass price ($92 vs $46). On pure material, the big piece is getting a relative discount.

This is the central trade-off in plain view. United inches understate how steeply area grows. Across small and mid sizes the discrepancy is absorbed by the band cushion and the labour bundling. But as pieces get genuinely large, the gap between “united inch price” and “true material cost” widens — which is exactly why the next section exists.

Where Mitre Fits

Doing these calculations by hand, job after job, is where errors creep in: a transposed dimension, a forgotten mat border, a glass band read off the wrong row. The arithmetic is simple, but it has to be right and identical on every quote, or your margins drift.

Mitre: Picture Framing Studio is built for exactly this. You enter the artwork size and the mat sizes you want, and Mitre computes the united inches, glass area, and moulding footage automatically — then applies your own per-united-inch and per-foot prices, your markup, tax, and shop minimum. It itemises moulding, mat, glass, backing, and labour, and produces a live to-scale proof plus a one-tap branded quote PDF and a shop cut-sheet (glass size, mat openings, frame outer size, chop length). It runs fully offline on iPhone, iPad, and Mac, with no account, no cloud, and no subscription — a one-time purchase.

Mitre — Picture framing quotes & proofs Download

Because Mitre uses your catalogue and your rates, the united inch logic in this post is applied consistently to every job — including the mat-border enlargement that is so easy to forget by hand. If you already run other parts of your shop on simple tools, it slots in nicely alongside spreadsheet utilities like CalXport for exporting figures to your accounts and XLPrinter for printing tidy worksheets, and Photo to PDF for turning client reference images into clean documents you can keep on file.

Common Pitfalls

The united inch method is forgiving, but it is not foolproof. These are the mistakes that cost shops money or confuse customers.

Mixing united-inch and square-inch methods

The most expensive error is inconsistency. If you price mat by united inches but glass by true square inches — or worse, switch methods depending on the job or who is at the counter — your quotes become unpredictable and your margins impossible to track. Pick a method for each material, write it into your price chart, and apply it the same way every time. The value of united inches comes almost entirely from that consistency, which is a strong argument for letting software apply the rules.

Forgetting that mat borders enlarge the outer size

This is the pitfall hiding in plain sight, and our worked examples leaned on it deliberately. The united inches of the artwork are not the united inches of the finished frame. A 16 × 20 print with a 3-inch mat border on every side becomes a 22 × 26 finished piece — that is 48 united inches, not 36. The frame moulding wraps the outer size, so the footage and the moulding cost are based on 22 × 26, and the glass and outer mat are cut to the outer size too. If you price the moulding off the artwork size, you will systematically undercharge for every matted piece, and the bigger the mat border, the worse it gets. Always carry the border math through to the outer dimensions before you read the moulding and glass figures.

Undercharging large pieces

As the contrast example showed, united inches understate the true area of big pieces. A shop that prices everything strictly by a flat per-united-inch rate, with no steepening for size, can end up giving away margin on its largest, heaviest, most labour-intensive jobs — the very jobs that consume the most expensive glass, the most material, and the most bench time, and that carry the most breakage risk. Two practical safeguards: build steeper price bands at the top of your chart (notice how the example glass prices jump more sharply at 60 and 80 UI), and consider a separate “oversize” surcharge above a threshold to recover the real cost of handling large glazing.

Ignoring the minimum charge

Very small pieces — a 4 × 6 photo at 10 united inches — can compute to a price so low it does not cover the time to set up the cutter, join a frame, and fit it. Every shop needs a minimum charge that the quote never falls below. United inch charts make the bottom of the range look cheap; the minimum is what keeps small jobs from running at a loss.

Not accounting for glazing tier

The same piece can carry very different glass prices depending on the glazing: standard glass, conservation (UV-filtering), museum, or anti-reflective. A united inch chart should have a column per tier, not a single glass price, or you will quote the wrong number when a customer upgrades. Conservation and museum glazing protect artwork from light damage and are a legitimate, well-understood upsell — but only if the chart prices them correctly.

Bringing It Together

United inches are a small idea that carries a lot of weight. By collapsing width and height into one number, framers get a fast, repeatable way to look up prices for mat, glass, and labour, and a number that maps cleanly onto the moulding perimeter. The method’s elegance is also its limit: it approximates area, so it can quietly undercharge long, skinny pieces and very large ones unless the chart is built with that in mind.

If you take three things from this post, take these: calculate united inches on the finished outer size, not just the artwork; keep one consistent method per material; and protect the extremes with a minimum charge and steeper top-end bands. Do that, and a united inch chart will price your work fairly and predictably for years.

For a wider look at the tools that run a modern frame shop — quoting, proofs, cut-sheets, and the back-office pieces around them — see our hub guide to the best apps for picture framing and frame shops. To go deeper on the parts of the quote this post touched, read how to price a custom picture frame, the single vs double mat guide, and the picture frame glass and glazing guide. If you are matching mat colours to an artwork, a tool like the Color Palette Safari extension can pull the dominant colours straight from a reference image. And if you are running framing as a small business, our notes on the best apps for small business owners and how to build a paperless office cover the back office around your bench.

Frequently Asked Questions

What does united inches mean in picture framing?

United inches is simply the width of a piece plus its height, added together into one number. An 11 × 14 piece is 25 united inches (11 + 14). Framers use this single number to look up prices for mats, glass, and labour on a price chart, because it is fast to calculate and grows smoothly as a piece gets bigger.

How do I calculate united inches?

Add the two dimensions together. Width plus height. That is the entire calculation — no multiplication. A 16 × 20 piece is 36 united inches. For pricing the frame itself, calculate united inches on the finished outer size (artwork plus mat borders), not just the artwork.

Why do framers use united inches instead of square inches?

United inches are faster to calculate at the counter (a sum, not a multiplication), produce small memorable numbers that fit neatly into price tiers, and map directly onto the moulding perimeter, which is twice the united inches. They are an approximation of area rather than the true area, but that trade-off buys huge gains in speed and consistency for most jobs.

Are united inches the same as square inches?

No. United inches are width plus height (a sum). Square inches are width times height (the true area). They are different numbers and answer different questions. United inches are a quick size index for pricing; square inches are the actual area, which matters most for glass and mat material and for very large pieces.

Do mat borders change the united inch number?

Yes, and this is a common mistake to overlook. Adding a mat border enlarges the finished piece. A 16 × 20 print with a 3-inch border on all sides becomes 22 × 26 inches — 48 united inches instead of 36. The frame moulding, glass, and outer mat are all cut to that larger outer size, so always carry the border math through before pricing.

Why might a flat united inch rate undercharge large pieces?

Because united inches grow in proportion to the sum of the dimensions, while glass and mat material grow in proportion to area, which rises far more steeply. A piece with double the united inches can have several times the area. Without steeper top-end price bands or an oversize surcharge, a flat per-united-inch rate can give away margin on big, heavy, expensive-to-handle pieces.

Can an app calculate united inches for me?

Yes. Mitre: Picture Framing Studio computes united inches, glass area, and moulding footage automatically from the artwork and mat sizes you enter, then applies your own per-united-inch and per-foot prices, markup, tax, and minimum. It produces an itemised quote, a to-scale proof, and a shop cut-sheet, and runs fully offline with no subscription.