Two-way humidity packs are the cheapest thing you can do to stop good material going stale, and most of the advice about them is wrong in one of two ways: it recommends silica gel, which does the opposite job, or it assumes the container you already own is sealed, which it usually isn't.
This page is the reference we wanted and couldn't find: the relative humidity numbers, the pack sizes, how often they get replaced, and — the part nobody publishes — which containers actually hold a humidity level long enough for a pack to matter. We don't sell or ship anything ourselves. Every product link below goes to its page on this site, where you'll find the full details and a link to buy it on Amazon.
The short answer
58% for anything you're using now. 62% for anything you're putting away. If you only remember one thing, remember that.
| Stage | Target RH | Why |
|---|---|---|
| Drying (roughly days 1–14) | ~60% RH at ~60°F | Slow is the entire point. This stage is about the room, not a pack in a jar. |
| Curing (roughly weeks 2–8) | 62% RH | A sealed jar with headroom, opened briefly each day for the first week or two. |
| Storage, in use | 58% RH | Drier burns better and tastes cleaner. This is the everyday number. |
| Storage, long term | 62% RH | Slightly damper protects against the slow drift downward over months. |
The drying figures come from our Croptober guide, which covers that stage properly.
Silica gel is the wrong tool, and it isn't close
Silica gel packets — the ones that come in a shoebox — are a one-way desiccant. They absorb moisture and they never give any back. Put one in a jar and it will keep pulling water out past the point you wanted it to stop, leaving material brittle and taking the terpenes with it. Brittle is not the same as dry, and it can't be undone.
A two-way humidity pack holds a saturated salt solution in a membrane. It releases moisture when the air around it is drier than its rating and absorbs moisture when the air is wetter. It targets a number instead of chasing zero. Boveda and Integra Boost are the two names you'll see; both work on the same principle.
Silica gel is correct for a camera bag. It is wrong for this. It does have a place in a kit, just not in the jar — colour-indicating silica packets are the right answer for glass and grinders after cleaning, for pen and battery cases, and for pulling a container that has gone genuinely too wet back down before a two-way pack can hold it steady. Keep the two jobs separate and neither one fights the other.
Pack size by quantity
Packs are sold by gram weight of the pack itself, not of what it's regulating. The convention manufacturers publish is roughly one pack per unit of the amounts below.
| You're storing | Pack size | Notes |
|---|---|---|
| Up to ¼ oz (~7 g) | 8 g (Boveda Size 8) | The small square. One per tube or small jar. |
| Up to 1 oz (~28 g) | 67 g | The common size, and the one worth buying in bulk. |
| Up to 1 lb (~454 g) | 67 g × 6, or 320 g | For a harvest-sized container, not a personal jar. |
Two smaller packs work as well as one larger pack of the same total weight, so an 8 g pack in each of ten tubes is fine. What doesn't work is one 8 g pack trying to regulate an ounce — it will exhaust itself in weeks and then do nothing while looking exactly the same.
When to replace
Every two to six months is the honest range, and the spread is that wide because it depends almost entirely on how well the container seals and how often you open it. A jar opened twice a day works a pack far harder than one opened twice a month.
How to tell without guessing: the pack goes rigid and hard when it's spent. While it's working it stays soft and slightly pliable, like a gel pack. If you can't dent it with a thumbnail, it's done. Some brands print a colour indicator on the pack — Integra ships an indicator card in every overwrap — and the thumbnail test works on all of them.
A cheap hygrometer removes the guesswork entirely, and is the one thing that tells you whether your container seals at all — watch whether the reading holds overnight or drifts back toward room humidity. They come six to a pack for the price of a sandwich, which is enough for every jar you own rather than one you keep moving around.
Which containers actually hold a humidity level
This is the part that decides whether any of the above matters. A humidity pack in a container that isn't airtight does nothing. It will equalise with the room, exhaust itself, and leave you with the same stale result plus the cost of the pack.
Fabric is the common failure. A carbon-lined pouch is built to stop odour molecules travelling outward through a liner; it is not built to stop water vapour moving in both directions, and it doesn't. Those pouches are good products doing a different job. Here's how what we curate actually sorts — specifications are as listed on each product page.
Sealed — a pack works here
| Container | Seal | Size as listed | Pack that suits it |
|---|---|---|---|
| CVault 2 oz Stainless Steel Container | Food-grade stainless, sealed lid, fully light-resistant | 2 oz | 8 g, and one is included — the lid has a holder for it |
| CVault ¼ lb Stainless Steel Container | Same seal and steel, built for long-term storage | ¼ lb | 67 g, and one is included |
| Herb Guard Auto-Cure Vacuum Seal Jar | Vacuum seal with auto-burp, hygrometer built into the lid | 1 litre, stated ~2 oz capacity | None needed for curing — it manages the cycle itself |
| ONGROK UV Glass Jars, 3-Pack | Frosted borosilicate, child-resistant lid, airtight seal | 180 ml (6 oz) each, up to 14 g | 8 g, one per jar |
| OZCHIN Bamboo Locking Box Set | Bamboo box with a lock — the box is not the seal; the two glass jars inside it are | Box 10 × 6.9 × 5 in, holding 2 glass jars and 2 XL tubes | 8 g, one per jar — never loose in the box |
| 116 mm Airtight Pre-Roll Tubes | Airtight, waterproof, child-resistant squeeze pop top | 116 mm (4.57 in) — takes a king size cone; sold in 50 or 100 | 8 g, and it will be a tight fit |
| Airtight Smell Proof Hard Case | Hard composite shell, two latches, stated waterproof and airtight seal | External 16 × 12.5 × 6.5 in; holds a piece up to 13.5 × 9 × 4.5 in | 320 g, or several 67 g |
For curing specifically, the Auto-Cure jar is the purpose-built answer — it burps on a schedule and reads the internal humidity from the lid, so you aren't opening it to find out how it's going, which is the one thing that costs you during a cure. Failing that, the glass jars in the OZCHIN box set do the job the traditional way: wide mouth, rigid walls, roughly three-quarters fill for headroom, opened briefly each day. A tube has none of those things — it's for portioning a finished cure, not producing one.
The CVault containers are worth calling out separately because they're the only things here that do all three jobs at once: the steel blocks light, the lid seals, and the humidity pack seats in the lid where it never touches what you're storing. Most storage makes you choose two.
Not sealed — a pack is wasted here
| Container | What it's actually for |
|---|---|
| FIREDOG Case with Combination Lock | 1680D fabric with a carbon liner, a lock and Velcro dividers. Odour containment and privacy, 8 × 4 × 2.75 in. Not a humidity environment. |
| Walnut Stash Box Set (9.5 in) | The exception among wooden boxes: it runs rubber airtight seals, so it does contain odour. It still holds no humidity level — use the two jars it ships with, and put the pack in one of those. |
| Carbon-lined pouches generally | Odour on the move. A liner and a zipper is not a seal. |
The useful middle case
The Herb Guard Large Smell Proof Case is soft-sided, so the case itself isn't a humidity environment — but it ships with a 50 ml UV glass jar, and that is. It's the right way round: the case handles odour, the lock handles privacy, and the jar inside handles freshness and light. Put the pack in the jar, not loose in the case.
Light and heat matter about as much
Humidity gets the attention because you can buy a product for it. UV does comparable damage and costs nothing to avoid: a cupboard beats a windowsill, and opaque or UV glass beats clear. Heat accelerates everything, including how fast a pack exhausts. Cool, dark and sealed is three-quarters of the job before a pack is involved at all.
If your storage lives somewhere with light on it, UV-resistant glass or opaque steel solves that for good, and neither needs any thought after you've bought it.
The full set, in the order we'd buy it
We now carry every piece of this. Written as a sequence rather than a list, because the order matters more than the total spend:
- A hygrometer first. It's the cheapest thing here and it tells you whether anything else you buy is working. Most people discover their favourite jar doesn't seal.
- Boveda 62% Size 8 if you're storing an ounce or less, Integra Boost 67 g if you're storing more. This is the consumable — plan on replacing it two to four times a year.
- A container that actually seals. CVault 2 oz for what you're using, CVault ¼ lb for what you're putting away, ONGROK UV jars if you want three labelled and on a shelf.
- The Auto-Cure jar only if you're actually curing. It's the most expensive item on this page and it solves a problem you don't have unless you grow.
- Silica packets for the gear, kept well away from the jars.
The rest of the picks are in the Lowkey Faves collection.
How we choose
Two filters. First, does the product do a job the cheap version does badly — sealing, airflow, odour, durability. Second, does the Amazon listing point at one specific item likely to still exist in a year, because a recommendation that dead-ends is worse than no recommendation. Specifications on this page are quoted from the product listings we link to, not measured by us.