Vape Cart Headspace: Why Your 510 Cart Looks Underfilled
Every 510 vape cartridge has some degree of headspace, the air gap that forms at the top after filling. If you've compared carts from different brands and noticed that some look fuller than others, rest assured that it’s not a filling error; it’s simply a difference in hardware.
Cartridge manufacturers deliberately design the tank to be slightly larger than the labelled fill volume, and the resulting headspace serves multiple purposes: it accounts for oil absorbed by the ceramic atomiser, prevents the pressure buildup that causes leaks, and leaves room for air displacement when the mouthpiece is pressed into place.
CCELL cartridges, which are among the most widely used hardware in the Canadian market (and the hardware GOOD BUDS uses for our live resin 510 carts), have some of the largest atomisers in the industry. It’s a deliberate engineering choice with real performance benefits, but it also means the headspace is more noticeable than on carts with smaller atomisers.
Here's what's going on inside, and why the trade-off is worth it.
Why do some 510 carts look emptier than others?
Two things: Atomiser size and tank size. Both vary across hardware manufacturers, and both affect how full a cart looks after it settles.
The ceramic atomiser inside the cartridge absorbs oil after filling. A cart with a smaller atomiser might absorb 50-80 mg. A CCELL cart absorbs up to 150 mg. The difference is visible. On top of that, different manufacturers build different amounts of extra room into the tank itself. A CCELL 1g cartridge has a total internal volume of roughly 1.25 ml, leaving 0.25 ml of headspace by design. Other manufacturers may leave more or less. The combination of atomiser absorption and tank design determines how full the cart looks once everything has settled.
If you've held two 1g carts side by side and one looks noticeably less full, the likely explanation is hardware differences rather than fill volume. Both carts were filled to the same weight. One just has more of that oil stored inside the atomiser, resulting in more engineered room in the tank.
What does a larger atomiser actually get you?
More consistent vapour production, better flavour, and a longer-lasting coil. A larger atomiser holds more oil in the heating element, so it's less likely to run dry between draws. In practice, the size difference translates to a few things:
More consistent vapour from first pull to last, because there's a larger reservoir of oil ready to vaporise at any given moment
Better flavour transfer, because the oil is wicked more evenly across a larger ceramic surface
Longer coil life, because the heating element isn't running dry between draws
The trade-off is cosmetic. A larger atomiser absorbs more oil, which means more visible headspace. The cart doesn't look as full, but the oil isn't gone. It's in the atomiser doing its job.
How does the filling process work?
Cartridges are filled by weight, not by volume or by eye. During filling, the oil is dispensed into the reservoir, and the weight is verified. A 1g cart receives exactly 1g of oil (within a very tight tolerance). At that moment, the reservoir is full to the top.
Over the next 24 to 48 hours, the atomiser gradually absorbs oil from the reservoir. Depending on the viscosity of the extract, a CCELL cart will settle from looking almost full to roughly 70-80% full in the visible window. It’s normal. The oil entered the atomiser, where it was ready to be vaporised.
A 1g CCELL cartridge actually has a total internal volume of roughly 1.25 ml. The "1g" on the label refers to the target oil fill, not the tank size. The extra 0.25 ml of capacity exists to accommodate atomiser absorption, leak prevention, and mouthpiece air displacement. Between the three, a filled cart will look about 70-80% full once it's settled.
| 1g Cart | 0.5g Cart | |
|---|---|---|
| Oil-filled (by weight) | 1,000 mg | 500 mg |
| Total tank volume | ~1,250 µl | ~700 µl |
| Oil absorbed by the atomiser | ~150 mg | ~150 mg |
| Oil visible in the reservoir after settling | ~850 mg | ~350 mg |
| Visible fill level | ~70–80% | ~70–80% |
The 20-30% air gap you see is the combined result of atomiser absorption, the extra tank capacity designed for leak prevention, and air displacement from the mouthpiece assembly. All 1,000 mg (or 500 mg) of oil is inside the cartridge. It just isn't all sitting in the visible reservoir.
Does the headspace do anything useful?
It does, and not just because of atomiser absorption. Headspace serves three functions inside the cartridge:
Oil absorption. The porous ceramic coil absorbs some of the oil during priming. It is what makes the oil available for vaporisation at the heating element.
Leak prevention. Filling a cartridge absolutely to the brim creates negative pressure inside the tank, which can force oil out through the bottom airway or cause it to spit through the mouthpiece. The headspace relieves that pressure.
Air displacement. When the mouthpiece is pressed into place during assembly, it displaces air inside the tank. Without room for that air to go, it would push oil out.
The same feature that makes the cart look less full is also what keeps it from leaking in your pocket.
Do you actually get all the oil?
All of it. The oil that the atomiser absorbed doesn't disappear. It vaporises just like everything else in the reservoir.
Here's the practical test: When the visible reservoir looks empty, you're almost certainly not done. There's still oil in the atomiser, so you'll usually get several more pulls from it. You'll know you're actually finished when the taste changes. Once the atomiser is truly dry, you'll get a burnt, coil-like taste instead of vapour. Until that happens, there's still oil being vaporised.
The headspace you see when the cart is new is the same volume of oil you get back at the end, as those final pulls. Nothing is lost.
How can you tell if a cart was actually underfilled vs normal headspace?
A properly filled cart with normal headspace will have a small, consistent air gap at the top, typically a few millimetres. The oil itself will be evenly distributed, with no large bubbles sitting in the middle of the reservoir and no gaps along the sides.
Signs of an actual filling issue could include: A dramatically uneven oil level, visible dry spots on the atomiser wick, or a cart that produces weak or burnt-tasting vapour from the very first draw. Those are hardware or filling problems, not headspace.
If you're ever unsure, ask the retailer where you purchased it. Licensed producers in Canada fill by weight with verified equipment, and retailers can connect you directly with the producer if there's a concern.
How GOOD BUDS fills its 510 carts
At GOOD BUDS, we use CCELL hardware for our live resin 510 cartridges because the larger atomiser matches the viscosity and terpene load of our extracts. Our Gluerangutan and Mango Cake live resin carts run high in natural terpenes, and a larger atomiser means more of that profile comes through on each draw.
Our filling process uses a semi-automatic machine that doses with a variance of 0.01g, well within Health Canada's requirements. Throughout every filling session, we run parchment fills interlaced with actual cart fills. These are test doses dispensed onto parchment paper and weighed independently to confirm the machine is maintaining accuracy. We also randomly pull carts from completed batches to validate fill weights. The combination of real-time parchment checks and post-fill audits means we're confident in every gram.
GOOD BUDS is a FVOPA Certified Organic cannabis producer on Salt Spring Island, BC. The same attention to process that goes into our living soil cultivation carries through to how we fill and QA our vape products.
If you're looking at a GOOD BUDS 510 cart and wondering why it's not full to the brim, now you know. It's full. The atomiser just got there first.
Alex Rumi is co-founder and Chief Strategy Officer at GOOD BUDS, an FVOPA Certified Organic cannabis farm on Salt Spring Island, BC. He has worked in the licensed Canadian cannabis industry since 2017.
Frequently Asked Questions
Why is there a bubble in my vape cartridge?
The air gap at the top of a 510 cartridge is called headspace. It forms because the ceramic atomiser absorbs oil after filling. How much headspace you see depends on the hardware manufacturer and atomiser size. CCELL carts have some of the largest atomisers in the industry (capable of absorbing up to 150 mg), so the gap is more noticeable than on other hardware. Every cart is filled by weight, so no product is missing.
Why does my cart look less full than other brands'?
Different cartridge manufacturers use different atomiser sizes. A larger atomiser draws more oil from the visible reservoir, creating more headspace. CCELL hardware uses larger atomisers for performance reasons (more consistent vapour, better flavour transfer), and the trade-off is a more visible air gap. The fill weight is the same.
Do I get less product because of headspace?
No. All the oil is accounted for and comes out during use. The absorbed oil vaporises just like the oil in the visible reservoir. When the reservoir looks empty, there are usually several pulls left from the oil stored in the atomiser. You'll know you're truly done when you taste the dry coil instead of vapour.
Is my GOOD BUDS 510 cart full?
Yes. GOOD BUDS uses CCELL hardware, which has a larger atomiser than most 510 cartridges, so the headspace is more visible. Every GOOD BUDS cart is filled using a semi-automatic machine accurate to within 0.01g, with parchment-fill weight checks run throughout every filling session. The cart will look about 70-80% full once the atomiser has absorbed its share, but the full gram (or half gram) is there.
