If you’re on the hunt for a new hot tub cover, getting the correct size is crucial to keeping your hot tub energy-efficient and well-maintained. A quality insulated hot tub cover helps your hot tub retain heat, reduces water evaporation, and protects your investment from outdoor elements. However, before picking out color options, thickness levels, or extra features, the first step is to accurately measure your hot tub. This guide will walk you through the process of measuring your hot tub to ensure you choose a cover that fits just right.
Why a Proper Fit Matters
Getting the right-sized hot tub cover isn’t just about aesthetics—it directly affects the performance and lifespan of your hot tub. Here’s why:
- Heat Retention: A too-small cover won’t fully seal the tub, allowing heat to escape. This forces your hot tub’s heater to work overtime to maintain the desired temperature, especially in cold weather. Over time, this increases your energy bills.
- Water & Chemical Loss: Steam and water vapor escaping from an ill-fitting cover lead to frequent water loss, meaning you’ll have to refill the hot tub more often. Plus, evaporating water takes some of your carefully balanced chemicals with it, leading to more frequent chemical adjustments and added costs.
- UV Damage: Exposed areas of the acrylic shell are vulnerable to the sun’s UV rays. Prolonged exposure can cause fading, cracking, or premature deterioration of the shell, cutting down on your hot tub’s longevity.
On the flip side, a cover that’s too large isn’t ideal either. Loose-fitting covers allow heat and vapor to escape from around the edges, causing the same energy and water loss issues. Additionally, condensation can collect on the cover skirt and drip around the spa, creating a mess and potentially damaging the exterior over time. A poorly fitting cover can also be prone to damage from wind or wear out faster due to improper alignment.
How to Measure Your Hot Tub for a New Cover
Before you begin, gather the following tools:
- Measuring tape
- Pencil and paper
- Carpenter’s square (or use two straight edges if you don’t have one)
It’s important to remove the old cover first. While you might be tempted to measure it, this can lead to inaccurate readings, since worn-out covers tend to warp or shrink over time. Measure the hot tub itself for the most accurate results. And remember: always measure to the outer edge of the acrylic, not the wooden frame. If your hot tub has a narrow top rail just below the acrylic edge, include this in your measurement.
Once you’ve gathered your tools, sketch your spa’s shape on a piece of paper to keep track of your measurements.
Step 1: Measuring the Cover Skirt
The cover skirt plays a key role in sealing off your hot tub and preventing heat from leaking out the sides. To measure the skirt, place a straight edge or carpenter’s square so it extends past the acrylic’s edge. Then, measure from the bottom of the straight edge to the edge of the acrylic. Add about one inch to your measurement to account for future shrinkage—so if your measurement is 4 inches, you should get a cover with a 5-inch skirt.
Step 2: Measuring the Safety Straps
Next, measure the safety straps that help secure the cover in place. Use the same method as above, but this time measure from the bottom of the straight edge to the top of the clip on the hot tub cabinet. The strap length should be at least one inch longer than the skirt. Don’t include the clip itself in your measurement, only the length of the strap.
Measuring Your Hot Tub Shape
Hot tubs come in various shapes, so here’s how to measure based on your specific type:
Round Hot Tubs
Simply measure across the center of the hot tub from one side to the other. The diameter is all you’ll need for a round hot tub cover. Make sure your measurement is precise, as this will be used to calculate the full circumference.
Square or Rectangular Hot Tubs with Straight Corners
Measure both the length and width of your spa. If your hot tub isn’t a perfect square, make sure to note which measurement corresponds to the fold. This will help you ensure the new cover folds in the correct direction.
Square or Rectangular Hot Tubs with Rounded Corners
Begin by measuring the length and width, like you would for a square or rectangular spa. Then, use a carpenter’s square to measure the curve radius. Place the square along the edge where the straight sides meet the curve, and measure from the edge to where the curve starts. Round down slightly if needed, as a smaller corner radius will ensure a snug fit.
Hot Tubs with Cut Corners
If your hot tub has one or more angled corners, measure the overall length and width first. Then, measure the size of the cut corner(s) and the lengths of the adjoining sides. Follow the instructions on the manufacturer’s order form to enter these details properly.
Hexagonal or Octagonal Hot Tubs
For six- or eight-sided spas, you’ll need to measure the total length from one side to the opposite side. Then, take a measurement of one individual side. Some manufacturers only need the total length, while others may ask for both the length and side measurements.
Oversized or Custom-Shaped Hot Tubs
For unusually large or uniquely shaped spas, such as swim spas or inground hot tubs, you’ll likely need a custom cover. These typically require more precise measurements and may need to be specially ordered. If your hot tub exceeds 96 inches in any direction or has an irregular shape, reach out to a hot tub cover manufacturer for assistance with a custom order.
Common Measurement Mistakes
One of the most common errors hot tub owners make is measuring their old cover instead of the hot tub itself. Since covers shrink and warp over time, this can lead to inaccurate measurements and a cover that doesn’t fit properly. Always measure the actual hot tub to avoid this issue.
Another mistake is not allowing for any wiggle room. Some manufacturers recommend adding an extra inch to your length and width measurements. This helps compensate for minor changes over time and ensures your cover isn’t too tight.
Ready to Buy?
Measuring your hot tub correctly is the first step in finding a cover that will save you money and extend the life of your hot tub. With the right measurements in hand, you’ll be well on your way to purchasing a hot tub cover that fits like a glove and protects your hot tub for years to come!
