When ordering a replacement hot tub cover, you may wonder whether you should measure the spa itself or simply copy the dimensions of your existing cover. The answer depends on the condition and fit of the cover you already have.
If your existing cover still fits correctly and has kept its original shape, it can provide a useful reference. If it is warped, stretched, sagging, too tight, or otherwise misshapen, measure the spa itself instead.
Before taking any measurements, there is an even easier first step: identify your spa manufacturer and model. If your model is already supported in the SpaCoverLabs database, verified specifications may reduce the amount of manual measuring required.
Should You Measure the Spa or the Existing Cover?
Use this simple rule:
| Situation | Best Starting Point |
|---|---|
| Existing cover fits well and keeps its original shape | Existing cover can be used as a reference |
| Existing cover is warped or sagging | Measure the spa |
| Existing cover has stretched or shrunk | Measure the spa |
| Existing cover never fitted correctly | Measure the spa |
| You are unsure whether the old cover is original | Measure the spa |
| Your exact spa model is in the database | Check the model specifications first |
The goal is not to reproduce an old cover simply because it is already there. The goal is to establish the dimensions and shape that the replacement spa cover actually needs.
Why Measuring an Old Hot Tub Cover Can Be Misleading
A hot tub cover changes over time.
Years of heat, moisture, UV exposure, weather, repeated opening and closing, and normal material ageing can affect its original shape.
An older cover may:
- stretch;
- shrink;
- sag through the centre;
- develop warped edges;
- become distorted around the hinge;
- or lose its original corner shape.
If you reproduce those altered dimensions, you risk transferring an existing fit problem to the replacement cover.
This becomes especially important when the old cover is already one of the reasons you are looking for a replacement.
If your cover is also unusually heavy, waterlogged, badly cracked, or losing its shape, see our guide to when to replace a hot tub cover.
When Can You Measure the Existing Cover?
An existing cover can still be useful when it is in good structural condition and you are confident that it fitted the spa correctly.
It may be suitable as a reference when:
- it sits evenly on the spa;
- the edges have not curled or warped;
- the foam has retained its shape;
- the corners still follow the spa correctly;
- the cover has not noticeably stretched or shrunk;
- and you know it was originally made for that spa.
Even then, it is sensible to compare the old cover with the spa itself before ordering.
If the measurements disagree, investigate why rather than automatically copying the old cover.
When Should You Measure the Spa Instead?
Measure the spa itself whenever the existing cover is no longer a reliable representation of the required size and shape.
This includes several common situations.
The Existing Cover Is Warped
A warped cover may lift away from one or more sides of the spa or no longer sit level.
Measurements taken from distorted material can therefore produce inaccurate dimensions.
The Cover Is Sagging
Structural deterioration or damaged foam can cause the centre of a cover to sag.
Although sagging primarily affects the vertical profile, it can also be accompanied by deformation around the edges and hinge.
The Cover Was Always Too Large or Too Small
If the old cover never fitted correctly, reproducing its dimensions makes little sense.
Return to the spa itself and establish the dimensions the replacement actually needs.
You Do Not Know Whether the Cover Is Original
When purchasing a used spa or moving into a property with an existing hot tub, you may have no way of knowing whether the current cover was originally made for that model.
In this situation, treat the spa itself as the more reliable reference.
The Old Cover Has Changed Shape
Flexible exterior materials and ageing internal components can change over time.
If the old cover looks noticeably different from the shape of the acrylic shell beneath it, measure the spa.
Where Exactly Should You Measure a Hot Tub?
For most installations, SpaCoverLabs recommends measuring from the outer edge of the acrylic shell.
The exact measuring point can depend on how the spa is installed.
Standard Spa Installation
For a typical freestanding spa, measure from the outer edge of the acrylic shell.
Spa with a Raised Rim
If the cover skirt is designed to seal against a raised rim, measurements may need to reference the outer edge of that rim.
Built-In Spa
For a spa installed into decking or another surrounding structure, the acrylic shell remains an important reference point. Skirt length may also need to reflect the visible height of the spa above the surrounding surface.
Because installation types differ, use the SpaCoverLabs step-by-step measuring guide before finalising your measurements.
What Measurements Do You Need for a Replacement Spa Cover?
Length and width are important, but they are not always enough.
Depending on the spa and cover design, the required information may include:
- overall width;
- overall length;
- shape;
- corner radius;
- skirt length;
- hinge position;
- installation type;
- and other model-specific details.
Rounded corners deserve particular attention. Two covers can have almost identical width and length while using noticeably different corner radii.
That is why accurate replacement-cover ordering involves more than simply copying two numbers from an old cover.
Why Corner Radius Matters
The corner radius describes how rounded the corners of your spa are.
A smaller radius produces a tighter corner, while a larger radius produces a more rounded corner.
If the radius is significantly wrong, the replacement cover may not follow the spa shell correctly even when its overall length and width appear correct.
Old covers can make radius measurement particularly difficult because the corners may soften, deform, or change shape over time.
If you are measuring manually, use the printable radius template and instructions in our measuring guide rather than estimating the corner by eye.
Should You Add Extra Centimetres to Your Measurements?
Do not automatically add arbitrary extra centimetres to a spa measurement unless the ordering instructions specifically tell you to do so.
The purpose of measuring is to provide the dimensions requested by the manufacturer or configurator. Any necessary manufacturing allowance should be handled consistently as part of the cover design rather than guessed by the customer.
Adding unnecessary allowance can produce a cover that is larger than intended.
Similarly, deliberately reducing measurements because you want a tighter fit can create problems.
Measure accurately and enter the dimensions requested.
Should You Measure More Than Once?
Yes.
Repeating important measurements is a simple way to catch mistakes before placing an order.
A practical process is:
- Take the first measurement.
- Write it down immediately.
- Measure the same dimension again independently.
- Compare the results.
- If they differ, measure again before continuing.
This is particularly useful for large spas and swim spas, where holding a measuring tape accurately over a longer distance can be more difficult.
Should You Measure in Centimetres or Millimetres?
Follow the units requested by the cover supplier or configurator.
The SpaCoverLabs measuring process uses centimetres and provides instructions for how measurements should be entered.
Do not switch between centimetres, millimetres, inches, and feet during the same measuring process unless you carefully convert the values.
Unit-conversion errors are easy to make and completely avoidable.
What If Your Spa Measurements Differ from the Model Database?
This is an important situation and should not simply be ignored.
Spa manufacturers can sometimes produce different revisions, production years, or regional versions under similar model names.
If your measurements do not match the specifications displayed for the model you selected, check:
- the manufacturer name;
- the exact model name;
- the production year if known;
- the serial number;
- and your measurements again.
Do not assume either the database or your first measurement must automatically be correct.
Recheck the information and, if necessary, contact SpaCoverLabs for assistance.
Photos of the spa, existing cover, or serial plate can also help clarify the configuration.
Find Your Spa Model Before You Measure
Before taking out the measuring tape, check whether your spa is already supported.
SpaCoverLabs maintains a database covering thousands of spa models across supported manufacturers. For many models, specifications such as shape, dimensions, and corner radius can already be available.
You can browse supported spa brands and find your spa model before beginning manual measurements.
This creates two straightforward ordering paths:
| If You Know Your Spa Model | If Your Model Cannot Be Found |
|---|---|
| Search the model database | Measure the spa |
| Review the stored specifications | Confirm length, width, shape, and radius |
| Check them against your spa | Use the custom configurator |
Search first. Measure when necessary.
What If You Are Still Unsure About Your Measurements?
Do not guess.
A few minutes spent checking a questionable measurement is much better than ordering a custom-made cover from information you do not trust.
If you are uncertain about the:
- spa model;
- width or length;
- corner radius;
- skirt length;
- installation type;
- or shape;
review the SpaCoverLabs measuring guide or contact our team.
You can provide photographs of your spa, existing cover, or serial plate along with your measurements to help clarify the correct configuration.
What If Your Existing Cover Still Fits Perfectly?
If the existing cover fits correctly, remains structurally sound, and has retained its shape, there is nothing wrong with using it as an additional reference.
In fact, it can be useful for checking:
- overall dimensions;
- corner shape;
- skirt length;
- hinge orientation;
- and how the cover sits around the spa.
The important distinction is between using an old cover as a reference and assuming that every old-cover measurement is automatically correct.
Whenever possible, compare those measurements with the spa itself or with verified model specifications.
What If Your Existing Cover Is Waterlogged?
A waterlogged cover should be treated cautiously as a measuring reference.
Moisture absorbed by the foam can increase weight and may contribute to distortion, sagging, or changes in the cover's shape.
If your old cover is very heavy or visibly deformed, measure the spa itself instead.
You may also want to read the 7 signs that a hot tub cover needs replacing to determine whether waterlogging or other structural problems are present.
Does the Age of the Existing Cover Matter?
Age by itself does not determine whether an old cover is suitable for measuring.
A relatively old cover that remains dry, correctly shaped, and well-fitting may still provide a useful reference. A younger cover that has become warped or waterlogged may not.
If you want to understand the factors that affect cover life, see our guide to how long a hot tub cover lasts.
Again, condition matters more than the calendar.
Common Measuring Mistakes to Avoid
Before ordering your replacement, check that you have not made one of these common mistakes.
Copying a Warped Old Cover
If the old cover has changed shape, you may simply reproduce its existing problem.
Measuring the Wrong Edge
Measure from the correct reference point for your installation rather than from surrounding cabinetry or decking unless specifically instructed.
Ignoring the Corner Radius
Rounded corners need more information than length and width alone.
Guessing Measurements
If a dimension is uncertain, measure again rather than rounding from memory or estimating visually.
Ignoring Differences from Known Model Specifications
If the model database and your measurements disagree noticeably, investigate the reason before ordering.
Assuming Every Spa with the Same Model Name Is Identical
Production revisions can occur. Confirm the information against the actual spa whenever practical.
Frequently Asked Questions
Is it better to measure the hot tub or the old cover?
If the old cover has warped, stretched, sagged, or never fitted properly, measure the hot tub itself. If the existing cover still fits correctly and retains its original shape, it can be used as an additional reference.
Can I copy the measurements printed on my old spa cover?
You can use them as a reference if you are confident the old cover was correctly made for your spa. Before ordering, compare them with your spa or verified model specifications rather than relying on the label alone.
What if my old hot tub cover is too large?
Do not reproduce its dimensions. Measure the spa itself following the correct reference points and use those measurements for the replacement-cover process.
What if my old cover is too tight?
If the cover has always been too tight, measuring and reproducing it could carry the same problem into the replacement. Measure the spa and confirm the shape and corner radius instead.
Can I measure a waterlogged spa cover?
A heavily waterlogged cover may be distorted and should not normally be relied upon as the primary measuring reference. Measure the spa itself and compare the results with any available model specifications.
Do I need to measure my spa if I know the model?
Not always. Start by searching for your spa brand and model. If verified specifications are available, they may reduce the amount of manual measuring required. You should still compare the displayed information with your actual spa before ordering.
What should I do if my measurements don't match the database?
Measure again and verify the exact spa model, model year, and serial information where available. If the difference remains, contact SpaCoverLabs and provide your measurements and photographs for review.
How do I measure rounded spa corners?
You need to determine the corner radius in addition to the overall width and length. Follow the radius instructions and printable template in our hot tub cover measuring guide.
So, Which Should You Measure?
When deciding whether to measure your spa or your existing hot tub cover, start by judging whether the old cover is still a reliable representation of the correct fit.
If it fits well and has retained its shape, use it as a useful reference.
If it is warped, stretched, sagging, waterlogged, incorrectly sized, or otherwise misshapen, measure the spa itself.
Better still, begin by identifying your spa model. Search the SpaCoverLabs model database to see whether specifications for your spa are already available.
If your model cannot be found, follow our step-by-step measuring guide and use accurate spa measurements to configure your replacement cover.
If anything remains unclear, send us your measurements and photos before ordering rather than guessing.
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