When you are preserving wedding flowers in resin, one of the first practical questions is: how much epoxy do I actually need?
The easiest way to figure it out is to use our free Counter Culture DIY Resin Calculator. Enter your project measurements and let the calculator estimate the resin amount for you. It is much faster than doing the math by hand and gives you a useful starting point before you begin your wedding flower preservation project.
Use the Free Resin Calculator →
If you want to understand how the calculation works, or double-check a mold manually, the guide below walks you through the formula.
Start with the inside dimensions of your mold
Measure the usable inside dimensions of the mold, not the outside. For a rectangular or square mold, measure:
- Length
- Width
- Planned pour depth
Then multiply those three numbers together.
Length × Width × Depth = cubic inches of mold volume
For example, an 8-inch × 8-inch piece poured 3 inches deep has a gross volume of:
8 × 8 × 3 = 192 cubic inches
Convert cubic inches to fluid ounces
One cubic inch is approximately 0.554 U.S. fluid ounces. So you can multiply the cubic-inch volume by 0.554 for a rough fluid-ounce estimate.
Using the 8 × 8 × 3 example:
192 × 0.554 ≈ 106 fluid ounces
That number represents the approximate volume if the mold were filled with liquid and contained no flowers.
Don't want to calculate it yourself? Use the Resin Calculator and enter your measurements.
Your wedding flowers take up space
A mold full of dried roses and greenery does not require the same amount of resin as an empty mold. The flowers displace some of the epoxy.
However, flower displacement is difficult to calculate exactly because every bouquet is different. A large rose can occupy significant space while airy greenery and baby's breath displace much less.
For an irreplaceable wedding bouquet, it is usually better to treat your calculated empty-mold volume as a planning ceiling and make sure you have enough resin available rather than trying to calculate flower displacement down to the ounce.
Do not mix the entire calculated amount automatically
Knowing the mold's total capacity does not mean you should mix and pour that entire amount at once.
Deep casting epoxies have recommended maximum pour depths and temperature ranges. Epoxy creates heat as it cures, so exceeding the manufacturer's recommended depth can create excessive heat and damage a casting.
Always follow the instructions for the specific resin you are using and divide a deep floral piece into pours when required.
How much extra resin should I have?
It is smart to have additional resin available beyond your exact estimate. Some resin remains in mixing cups and on stirring tools, and unexpected voids around flowers can consume more material than you anticipated.
Having extra product on hand is particularly important for wedding flower preservation because stopping midway through a project to order more resin is not ideal.
Common wedding flower mold examples
These examples show gross mold capacity before accounting for flowers. Actual resin use will vary.
| Mold Size | Gross Volume | Approx. Fluid Ounces |
|---|---|---|
| 6 × 6 × 2 in. | 72 cu. in. | 40 fl. oz. |
| 6 × 6 × 3 in. | 108 cu. in. | 60 fl. oz. |
| 8 × 8 × 2 in. | 128 cu. in. | 71 fl. oz. |
| 8 × 8 × 3 in. | 192 cu. in. | 106 fl. oz. |
| 10 × 10 × 2 in. | 200 cu. in. | 111 fl. oz. |
| 10 × 10 × 3 in. | 300 cu. in. | 166 fl. oz. |
These are geometric estimates for rectangular molds. Flowers reduce the actual amount of resin required.
What about hexagon and irregular wedding flower molds?
Hexagons, arches, hearts and other decorative molds require a different volume calculation than a rectangle. If the mold manufacturer lists its capacity, use that figure as your starting point.
If capacity is not listed, one practical option is to determine the mold's volume before using your wedding flowers. Whatever method you use, make sure the mold is completely clean and dry before resin is introduced.
Should I calculate by weight or by volume?
Use the mixing directions supplied with your resin. Some epoxy systems specify a mixing ratio by volume, others by weight, and the two ratios are not automatically interchangeable.
Do not assume that a 1:1 volume ratio is also 1:1 by weight unless the manufacturer specifically says so.
Choose a casting resin for deep floral pieces
Wedding bouquet blocks are very different from thin surface coatings. For thick molds, use a clear casting epoxy intended for casting applications and stay within its recommended pour depth.
Culture Cast Flower Preservation Resin is Counter Culture DIY's casting epoxy for floral preservation and deep casting projects.
If you are comparing products, read Best Resin for Wedding Flower Preservation: What to Look For.
Plan the flowers before calculating your final pour
Arrange your completely dried flowers in the empty mold first. This lets you see how much of the mold the bouquet occupies and whether your planned depth is actually necessary.
Take a photo of the arrangement before removing the flowers. You can use that photo as a reference when it is time to cast.
If your flowers are not dry yet, start with How to Dry Wedding Flowers for Resin Preservation.
Wedding flower epoxy amount FAQs
Is there an easier way to calculate how much epoxy I need?
Yes. Use our free Counter Culture DIY Resin Calculator to estimate the resin needed from your project measurements without doing the calculations by hand.
How do I calculate resin for a rectangular mold?
Multiply the inside length × inside width × planned depth. That gives you cubic inches. Multiply cubic inches by approximately 0.554 to estimate U.S. fluid ounces.
Do flowers reduce how much epoxy I need?
Yes. Dried flowers occupy volume inside the mold and displace resin, but the amount varies widely based on the size and density of the flowers.
Should I buy exactly the amount my calculation says?
It is safer to have additional resin available. Your mold calculation is an estimate, and resin is also lost in mixing containers and around tools.
Can I pour all the resin at once?
Only if that pour is within the resin manufacturer's recommended depth and conditions. Deep castings may require multiple pours.
Can I calculate epoxy before I dry my wedding flowers?
You can estimate the mold's gross capacity, but final planning is easier after the flowers are fully dried and you can arrange them inside the mold.
Ready to cast your wedding flowers?
First, use the Resin Calculator to estimate how much resin you need. Once you know your approximate resin requirement and your flowers are completely dry, follow our complete wedding flower preservation guide.
For more inspiration, see Wedding Bouquet Preservation Ideas, and review How to Keep Flowers From Turning Brown in Resin before casting your irreplaceable bouquet.
Shop Culture Cast Flower Preservation Resin when you are ready to begin.