How to Measure Custom Patio Deep Seating Chair Covers: The Four-Number Framework

A patio deep seating chair cover is one of those things you don't think about until yours fails. Then you spend a weekend trying to find one that fits, discover that every off-the-shelf option is either too small in the arms or too short at the back, and end up back where you started with a chair that spends its off-hours getting rained on.

The issue isn't that outdoor chair covers are hard to make. The issue is that deep seating chairs come in more shapes than any other category of patio furniture. Two chairs from the same brand can have four inches of difference in arm width, three inches at the back, and different rake angles on the seat.

A universal cover treats all of them as if they were the same silhouette — which is why so many end up on garage shelves after one summer.

Getting a patio deep seating chair cover that actually fits comes down to four numbers, taken correctly. Arm-to-arm width. Seat depth. Back height. Front height. This guide walks through each one, then explains why deep seating chairs need a heavier fabric than most patio covers, and what to expect from the order once you place it.

Why Do Deep Seating Chairs Need Custom Covers?

Standard patio chairs — the folding kind, the four-legged aluminum kind — have predictable geometry. The seat is 16 to 18 inches wide, the back is 20 to 22 inches tall, and the whole thing collapses down to something a cover shaped as a rectangle can handle.

Deep-seating chairs work on entirely different math. The frame is wider than a dining chair (usually 30 to 34 inches at the arms), the seat sits low (14 to 16 inches off the ground with cushions in place), and the back rakes at 5 to 15 degrees off vertical, depending on the design.

Then there's the cushion overhang: a deep seating chair cushion typically sits an inch or two proud of the seat frame at the front, and the cover has to clear that overhang, or it pulls the seat cushion out of place every time it goes on.

This is where the four-number framework earns its keep. Every one of those numbers accounts for one specific geometry problem. Miss any of them and the cover will fit somewhere between OK and useless. Get all four, and the cover sits like it was tailored to the chair because it was.

The Four Numbers That Actually Matter

1. Arm-to-arm width

Measure across the outside of the two arms, at their widest point. Not the seat width. Not the frame width. Arm-to-arm, outer edge to outer edge. For most deep seating chairs, this number is 28 to 36 inches. If your chair has flared or angled arms, take the measurement at the widest span they reach, not where they meet the backrest.

The most common mistake here: measuring the seat cushion instead of the arms. The cushion is narrower than the arms on almost every deep seating chair, and a cover cut to the cushion width won't clear the arms when it comes down over the top.

2. Seat depth (front cushion edge to backrest)

From the front edge of the seat cushion (in place, as you'd sit on it) to the front face of the backrest cushion. This is typically 22 to 28 inches on a deep seating chair. Measure with the cushion actually on the chair — not the frame depth. The cushion overhang at the front is what the cover has to clear.

If your chair has a removable back cushion that gets tossed on and off, measure to where the back cushion sits when it's on. That's the seat depth the cover is drawn against.

3. Back height (ground to top of backrest)

Straight vertical measurement from the ground to the highest point of the chair — usually the top of the backrest cushion (or the frame, if the back cushion doesn't reach the top). This is where most people get thrown off. Don't measure along the angle of the back. Measure the vertical drop from the top of the back to the floor.

For most deep seating chairs, back height is 34 to 42 inches. Angled backs read taller than vertical backs, even when the frame is the same — a chair with a 15-degree rake back can measure 3 or 4 inches taller than the same frame with a 5-degree rake.

4. Front height (ground to top of front rail)

Ground to the top of the seat cushion at the front of the chair — the point that would sit right behind your knees. This is usually 16 to 22 inches. This number matters because the cover slopes from the tall back down to the shorter front. Without both back height and front height, the cover has to guess at the slope, which usually means it comes down too tight on one end and too loose on the other.

Add 1 inch of ground clearance to both height numbers before you enter them. That's the standard buffer that keeps the hem off the patio and lets a little airflow underneath — enough to prevent trapped humidity without letting wind lift the cover.

Why 18 oz PVC Matters More on Chair Covers Than on Larger Pieces?

Chair covers get handled more than any other patio cover. Sofa and table covers come off maybe once a season. Chair covers come off every time someone sits down, which on a well-used patio can be several times a week during warm months. That daily on-and-off cycle wears out the drawstring channel, the corner seams, and the hem faster than any single storm ever will.

This is why the fabric weight actually matters here. 18 oz 1000 Denier PVC-coated polyester (what we build the ZIP Armor line from) holds up to that abrasion for years. A lighter cover — the kind of 600-denier polyester most off-the-shelf chair covers ship in — tears at the arm corners within a season. You'll see the fraying start at the inside seam where the cover flexes every time it goes on.

Beyond the abrasion resistance, the heavier fabric holds its shape when the cover is off the chair. That matters more than it sounds. A lightweight cover flops into a shapeless pile between uses; getting it back onto the chair takes time, and the time cost is what makes people stop using it. A stiffer cover keeps the same silhouette it had on the chair, which means going back on takes about six seconds instead of a minute.

Securing a Chair Cover in Wind Country

Bottom drawstrings are standard on every ZIP Armor cover. On a chair, the drawstring runs around the entire hem and tightens the cover against the frame legs. That alone holds the cover in calm and moderate wind. In hurricane country, coastal patios, or hilltop yards where storms roll through with intent, add the leg-buckle strap upgrade.

The leg buckles anchor the cover at four points — one strap loops under each chair leg and clicks into the hem. This isn't overkill for a chair cover, even though the piece is small. A chair cover is lighter than a sofa cover and lifts off in a gust of wind faster. The buckles cost nothing extra on most cover styles and add years to the working life in windy locations.

If you have multiple chairs on the same patio, order all of them with buckles. It's easier to standardize than to remember which chair has the upgrade and which doesn't — and consistency across a set of chairs looks better than mismatched securing options.

Care Habits That Extend a Chair Cover's Life

The single most important habit for a chair cover: lift it off by the top center, not by the corners. Grabbing corners drags the fabric against the arm and stretches the drawstring channel over a season. Lifting from the center pulls the cover straight up off the chair, no drag.

Once a month, flip the cover inside out and let it fully dry in the sun before turning it back and re-securing. The interior — the side that faces the chair frame — collects most of the humidity, and mildew usually forms where the drawstring bunches against wet fabric. A monthly airing prevents that entirely.

For everyday cleaning, hose the outside down after pollen-heavy weekends and after any bird activity overhead. For deep-set stains (sap, resin, an accidental splash of grill grease from a nearby BBQ), a paste of baking soda and warm water lifts most of it without touching the PVC coating. Skip bleach and pressure washers — both shorten the UV inhibitor's life.

What Happens After You Place the Order?

Every deep-seating chair cover order goes through a review before the vinyl is cut. Customer care looks at your four numbers and checks them against the chair type you selected on the product page. If back-height and front-height came in as the same number, that's a flag — angled chair backs are always taller at the back than the front, so an equal number usually means one was measured wrong.

If the numbers look right, the 18 oz PVC-coated polyester is cut from a single bolt to your sizing. Seams are heat-welded rather than stitched — no needle holes for water to find — and ventilation grommets go on the side panels to release humid air after rain. Reinforced corner panels handle the abrasion from daily removal and replacement.

Once the cover ships, tracking arrives by email. The 10-year warranty on the ZIP Armor line covers manufacturer defects — seam separation, coating failure, and cover-fit issues. If anything about the fit doesn't read right when the cover arrives, customer care will work it out with you directly at sales@zipcovers.com or +1 720-882-0756.

Quick Answer

Related Guides & Collections from ZIPCovers

Browse the collection: Custom Chair Covers · Custom Sofa Covers

Build yours: Custom Patio Deep Seating Chair Cover

More on this topic: Custom Patio Lounge Chair Covers

Frequently Asked Questions

Should I measure my chair with the seat cushion on?

Yes — measure with the seat cushion in place, positioned the way you'd sit on it. Deep-seating chair cushions overhang the frame at the front by 1 to 2 inches, and the cover has to clear that overhang or it'll pull the cushion out of place every time the cover goes on. If your chair has a removable back cushion, measure to where the back cushion sits when it's on. That's the seat depth the cover is drawn against.

What if my chair has flared or angled arms?

Take the arm-to-arm width at the widest span the arms reach, not where they meet the backrest. Flared arms are common in modern deep-seating designs (mid-century-inspired frames, teak lounge chairs, curved metal frames), and the widest point is usually near the front of the arm. A cover cut to the frame width will bind on the arms.

If the flare is dramatic, note it in the order comments — customer-care can add a small dart at the arm curve for a cleaner drape.

How do I know if I need the leg-buckle strap upgrade?

If your patio is exposed to wind — coastal, hilltop, storm-prone regions, or any yard where a summer thunderstorm regularly rolls through — order the buckles. The bottom drawstring alone holds a chair cover snug in calm and moderate wind, but chair covers are lighter than sofa covers and lift off in a gust faster than most people expect. The buckles anchor the cover at four points under the chair legs and prevent that lift.

Cost is nominal on most cover styles, and it adds years to the working life in windy locations.

Do you make custom covers for irregular chair shapes?

Yes — custom covers ship in any shape, including chairs with unusual footprints, extended arms, integrated ottomans, or built-in side tables. For anything that doesn't match a standard product page, use the Custom Shape product page and upload a sketch with dimensions marked on each edge. For chairs with an attached ottoman or side table (like some outdoor sectional pieces), send a photo along with the measurements so customer care can confirm the intent before cutting.

Email sales@zipcovers.com or call +1 720-882-0756 to walk through the order.

What is the warranty period on a ZIP Armor chair cover?

The Zip Armor line — 18 oz 1000 Denier PVC-coated polyester — carries a 10-year warranty. The Zip Shield line — the lighter standard-weight construction — carries a 7-year warranty. Both warranties cover manufacturer defects (seam separation, coating failure, cover-fit issues). They don't cover damage from mishandling (a garden shear cut, a chewed corner, an object dropped through the top). To make a claim, email sales@zipcovers.com with photos of the issue and your order number.

Build Your Deep Seating Chair Cover

A patio deep seating chair cover that fits right doesn't look like a cover at all — it looks like the chair is wearing the frame's silhouette in a slightly different color. When people notice the cover, it's usually because it fits badly. When they don't, it's fitting right.

Take your four numbers. Add the 1-inch ground clearance to the heights. Choose the buckle upgrade if you're anywhere real wind reaches. Place the custom order. It'll outlast the chair you measured it for — that's what the 10-year warranty on the ZIP Armor line really means.