How to Measure Your Roll-Up Garage Door for BlueTex™ Insulation (Square Footage Will Lead You Astray)
BlueTex™ Roll Up Garage Door Insulation Kits come with everything you need to insulate your metal roll up door, while still allowing you to open/close the door with no problems. Our pre-made kits make it easy to choose your size and checkout. But what if you have multiple doors to cover? If you're unsure which size to get or would like to know how to measure and calculate the coverage your door needs, continue reading below.
When most people shop for garage door insulation, they look at one number: the square footage of the door. It feels natural — after all, you're covering a flat surface. But for roll-up garage doors, square footage alone will lead you to order the wrong kit almost every time.
BlueTex™ garage door insulation is sold on a roll. That roll has a fixed width (50" or 62" wide) and a fixed length. When you insulate a roll-up door, you cut horizontal strips of insulation to match the width of the door and then install pieces right next to each other from the floor to the top of the door. This means the material you use is measured in linear feet, not square feet.
This guide will teach you how to calculate the right number so you order the right kit on the first try.
The Key Concept: Horizontal Runs on the Door
A standard BlueTex™ garage door insulation roll is 50 inches wide — 4 feet with 2 inches for overlapping on the top and bottom of the run. When you apply it to a roll-up door, you cut it into horizontal strips and lay them across the door from bottom to top. Each strip covers 4 feet of door height.
That means:
- A 10-foot door needs 3 horizontal runs (2' top + 4' middle + 4' bottom)
- A 12-foot door needs 3 runs (4' top + 4' middle + 4' bottom )
- A 14-foot door needs 4 runs (2' top + 4' middle + 4' middle + 4' bottom)
The length of material you consume comes from how wide the door is — not how tall. Every run stretches the full width of the door.
The Golden Rule: Don't calculate square footage. Divide your doors HEIGHT by 4 to find how many horizontal runs you need, then multiply by the door WIDTH to get your linear footage.
The Formula
- Door height ÷ 4 = number of runs (round up)
- Number of runs × door width = linear feet per door
- Linear feet per door × number of doors = total linear feet needed
That total linear feet number is what you use when choosing your kit.
A Note on the 2-Foot Top Strip
Depending on the height of your roll up garage door, you may have less than 4 feet left to cover at the top. This is the case with 10' doors and 14' doors. Because the standard BlueTex™ door kit rolls are 50 inches wide, you can cut one full-length strip in half lengthwise to get two 25"-tall pieces. This means one strip covers the top of two different doors, saving you material.
If you have multiple doors to cover that have a height measurement divisible by 5', you can consider the Multi-Door Garage Door Insulation Kit in the 62" wide roll that will cover a 10' x 10' door with 2 horizontal runs (5' top half, 5' bottom half) or a 14' x 14' door with 3 horizontal runs (4' top (trim off 12"), 5' middle, and 5' bottom).
In the examples below, we'll show both the maximum linear footage (no sharing of pieces across the top of the doors) and the minimum (sharing top strips across pairs of doors) so you know your range.
Example 1: Three 10' Wide × 10' High Doors
The square footage error: 10' × 10' = 100 sq ft per door. Three doors = 300 sq ft total. You might think you need a 300 sq ft roll — but a 300 sq ft roll is only 72 linear feet long. Here's why that's a problem:
Step-by-Step Calculation
| Step | Calculation | Result |
|---|---|---|
| Door height ÷ 4 | 10' ÷ 4 | 2.5 → round up to 3 runs |
| Runs × door width | 3 × 10' | 30 linear feet per door |
| × number of doors | 30 × 3 | 90 linear feet (maximum) |
Sharing the top strip: You can cut one 10' piece in half lengthwise and use it across the tops of two doors. That saves 10 linear feet — bringing your minimum down to 80 linear feet.
Why the Oversize Door Kit falls short: Its roll is only 72 linear feet. Even at the minimum of 80 linear feet needed, you'd run out before finishing all three doors.
Total linear feet needed for three 10' x 10' doors is 80' – 90'
Recommended Products: If sharing a top strip across 2 of 3 doors: 1x Single Door Kit (37.5' long roll) + 1x Double Door Kit (52.5' long roll) — OR — 1x Multi-Door Kit in the 62" wide style (135' long roll) to cover all three with material to spare.
Example 2: Two 14' Wide × 14' High Doors
The square footage error: 14' × 14' = 196 sq ft per door. Two doors = 392 sq ft. You might look for a ~400 sq ft solution — but again, what matters is the roll length.
Step-by-Step Calculation
| Step | Calculation | Result |
|---|---|---|
| Door height ÷ 4 | 14' ÷ 4 | 3.5 → round up to 4 runs |
| Runs × door width | 4 × 14' | 56 linear feet per door |
| × number of doors | 56 × 2 | 112 linear feet (maximum) |
Sharing the top strip: One 14' piece split lengthwise covers the top panel of both doors. That saves 14 linear feet — bringing your minimum down to 98 linear feet.
Total linear feet needed for two 14' x 14' doors is 98' – 112'
Recommended Products: If sharing a top strip across the 2 doors: 1x Double Door Kit + 1x Oversize Door Kit — OR — 1x Multi-Door Kit in the 50" wide style (168' long roll) or the Multi-Door Kit in the 62" wide style (135') for the less expensive options (you will have leftover material from the multi-door kits).
Example 3: Four 12' Wide × 12' High Doors
The square footage error: 12' × 12' = 144 sq ft per door. Four doors = 576 sq ft. That sounds like a big order — but the linear footage required is a very specific number.
Step-by-Step Calculation
| Step | Calculation | Result |
|---|---|---|
| Door height ÷ 4 | 12' ÷ 4 | 3 runs (exact) |
| Runs × door width | 3 × 12' | 36 linear feet per door |
| × number of doors | 36 × 4 | 144 linear feet (maximum) |
Sharing the top strip: Because these doors are a multiple of 4, no need to share a top strip of insulation. They each get exactly 3 strips of 50" wide material. Because of this, you just need 144 linear feet.
Total linear feet needed for four 12' x 12' doors is: 144'
Recommended Product: You can make this work with the 50" Wide Oversize Door Kit but you need to plan to cut exactly at 12' and not longer or you'll run short. If you like having extra material on hand, consider bumping up to the Multi-Door Kit in the 50" wide style (168' long roll) to ensure you will have material to spare.
Summary: All Three Examples at a Glance
| Configuration | Sq Ft | # of Runs/Door | Length Needed Per Door | Min Total Linear Ft | Max Total Linear Ft |
|---|---|---|---|---|---|
| 3 doors @ 10'W × 10'H | 300 sq ft | 3 runs | 30' | 80' | 90' |
| 2 doors @ 14'W × 14'H | 392 sq ft | 4 runs | 56' | 98' | 112' |
| 4 doors @ 12'W × 12'H | 576 sq ft | 3 runs | 36' | 144' | 144' |
Quick Reference: How to Measure Your Door in 3 Steps
- Measure your door's height and width in feet.
- Divide the height by 4 (because our standard roll is 50" wide - 4'2") and round up — that's the number of horizontal runs you need per door.
- Multiply: runs × width × number of doors — that's your total linear footage.
Once you have that number, find a kit whose roll length meets or exceeds it. When in doubt, round up — it's always better to have a few extra feet than to run short mid-install.
Still not sure which kit is right for your setup? Contact us and we'll help you figure it out in minutes.