Making gelatin capsules at home is straightforward with an inexpensive manual capsule filler and a few basic supplies. The process involves separating empty capsule shells, filling the bottom halves with your powder, tamping it down, and snapping the caps back on. Most people can fill 24 to 100 capsules in about 15 to 30 minutes once they get the hang of it.
What You Need to Get Started
The essential equipment is a manual capsule filling machine, which typically costs between $15 and $40 and comes in versions that hold 24, 50, or 100 capsules at a time. These machines have three main components: a base plate that holds the bottom halves of the capsules upright, a cap plate that collects the top halves, and a tamping tool used to press powder down into the capsule bodies. You’ll also need a small spreader card (often included) to push powder across the base plate.
Beyond the machine, gather your powder, a digital scale accurate to at least 0.01 grams, empty capsule shells in your chosen size, and a clean workspace. A small bowl or mortar and pestle is useful if you need to blend powders before filling.
Choosing the Right Capsule Size
Empty capsules come in sizes ranging from 4 (smallest) to 000 (largest). The right size depends on your per-capsule dose. Here’s what each size holds:
- Size 000: 1.37 ml volume, holds roughly 950 to 1,370 mg of powder
- Size 00: 0.95 ml, holds 665 to 950 mg
- Size 0: 0.68 ml, holds 475 to 665 mg
- Size 1: 0.50 ml, holds 350 to 475 mg
- Size 2: 0.37 ml, holds 250 to 350 mg
- Size 3: 0.30 ml, holds 200 to 300 mg
- Size 4: 0.21 ml, holds 150 to 200 mg
The weight ranges vary because powder density differs from one substance to another. A fluffy, light powder like turmeric will fill toward the lower end of the range, while a dense powder like magnesium oxide packs in closer to the upper limit. Size 00 is the most popular for home use because it holds a meaningful dose without being difficult to swallow. Size 000 capsules are noticeably large and can be uncomfortable for some people.
To figure out your ideal size, weigh out your target dose, pack it into a single capsule by hand, and see if it fits with a little room to spare. You want enough space that the cap can close fully without resistance.
Gelatin vs. Plant-Based Capsules
Empty capsules come in two main types: gelatin (made from animal collagen) and HPMC (a plant-derived cellulose). For most home filling purposes, both work the same way and fit the same machines. The differences matter more for storage and compatibility with certain fills.
Gelatin capsules contain 13 to 16% moisture and can become brittle if stored in very dry conditions. In humid environments, they absorb water and soften relatively quickly. HPMC capsules carry less moisture (4.5 to 6.5%) and respond more gradually to humidity changes, making them more stable if your storage conditions aren’t perfectly controlled. HPMC capsules also resist becoming brittle, which means fewer cracked shells during filling. If you’re vegetarian or vegan, HPMC is the obvious choice, but even if you’re not, they tend to be more forgiving to work with.
Step-by-Step Filling Process
1. Prepare Your Powder
Weigh out enough powder to fill your entire batch. If you’re combining multiple ingredients, blend them thoroughly in a bowl first. Clumpy or coarse powders should be sifted or ground finer, since large particles create air pockets and uneven fills. Calculate your total by multiplying your per-capsule dose by the number of capsules you plan to fill, then add about 10% extra to account for what sticks to your tools and tray.
2. Separate the Capsule Halves
Place your empty capsules into the base plate with the longer body half pointing down. Most manual fillers are designed so you load the capsules whole, then lift off the cap plate, which pulls the shorter cap halves away from the bodies. Set the cap plate aside. You should now have a tray of open capsule bodies standing upright, ready to be filled.
If any capsules fail to separate, gently twist them apart by hand and place the body back into the base plate. Don’t force a capsule that’s stuck, as this can crack or dent the shell.
3. Add and Spread the Powder
Pour your powder onto the base plate, directly over the open capsule bodies. Use the spreader card to push the powder back and forth across the surface, working it into each capsule. Take your time here. Sweeping too quickly sends powder flying and leaves some capsules underfilled.
4. Tamp the Powder Down
Once the capsules look full, press the tamping tool evenly across the tray. This compresses the powder, creating room for more. Add another layer of powder, spread it in, and tamp again. Most capsules benefit from two or three rounds of tamping and refilling to reach a consistent, full dose. Tamp with gentle, even pressure. Pounding too hard can crack the capsule bodies or over-compress the powder, which may slow down how quickly the capsule dissolves later.
5. Sweep Away Excess Powder
After your final tamp, use the spreader card to clear all loose powder off the top surface of the base plate. You want the tops of the capsule bodies clean so the caps can seat properly. Brush gently to avoid pulling powder back out of the capsules.
6. Lock the Capsules
Align the cap plate over the base plate so each cap lines up with its body. Press the plates together firmly and evenly. You should feel (and sometimes hear) the capsules click shut. Most manual fillers have a built-in mechanism that applies even pressure across all capsules at once. Once locked, remove the finished capsules from the tray.
Filling Capsules With Liquids
You can fill hard-shell capsules with oils and other liquids, but the fill must be compatible with the shell material. Oil-based fills work well: carrier oils, MCT oil, and medium-chain triglycerides like caprylic/capric triglycerides are all compatible with gelatin. PEG 400, a common pharmaceutical solvent, also performs well and dissolves active ingredients more effectively than oils in most cases.
Water-based liquids are a problem. Gelatin dissolves in water, so any fill with significant water content will break down the capsule from the inside before you can use it. If you need to encapsulate something water-soluble, dissolve it in a compatible liquid carrier first, or use a powder form instead.
For liquid fills, skip the capsule filling machine and use a small syringe or dropper to fill each capsule body individually. Fill to about 90% capacity to leave room for the cap to seat without squeezing liquid out. Work quickly, since open gelatin capsules begin absorbing moisture from the air.
Inspecting Your Finished Capsules
After filling a batch, take a minute to check your capsules before storing them. Look for cracks, splits, or dents in the shell. Check that each capsule is fully closed with no visible gap between the cap and body. A properly locked capsule should feel firm when you gently squeeze it, with no wiggle between the two halves. Discard any capsule that shows misalignment, leaking powder from the seam, or a shell that looks deformed.
If you want to verify dosing accuracy, weigh five or six random capsules from the batch. Subtract the weight of an empty capsule (weigh a few empties beforehand to get an average). The fill weights should be reasonably close to each other. If they vary by more than 10 to 15%, your tamping was uneven, and you may want to adjust your technique for the next batch.
Storing Capsules Properly
Gelatin capsules are sensitive to both heat and humidity. Store them below 25°C (77°F) in a cool, dry place. Above 35 to 40°C, gelatin softens significantly and the capsules can deform or stick together. Humidity above 60% accelerates moisture absorption, which makes gelatin capsules tacky and prone to clumping. At humidity levels above 80%, gelatin becomes unstable at body temperature.
An airtight container with a silica gel packet is the simplest storage solution. Amber glass jars or opaque containers also protect light-sensitive fills. HPMC capsules are more tolerant of humidity swings, but storing them in similar conditions is still good practice. Under proper conditions, filled capsules generally stay usable for several months, though this depends on the stability of whatever you’ve put inside them.