Deep Dive
Buying Welding Gas in Australia: A Complete Guide to Not Getting Ripped Off
What welding gas really costs per year in Australia: cylinder hire vs swap-and-go vs outright purchase — the maths nobody explains, decoded from actual Australian gas supplier pricing.
Walking into a gas supplier for the first time is like walking into a casino: the house has all the information, you have none, and the pricing structure is designed to be confusing on purpose. Cylinder hire, swap-and-go, outright purchase, refill-only, deposit systems — each has its place, and choosing the wrong one costs you hundreds of dollars a year.
We decoded the pricing structures of the three major Australian gas suppliers (BOC, Supagas, Coregas) and ran the numbers for different usage profiles. Here's what we found. (If you only want the price list, the observed BOC, Supagas and Coregas numbers by bottle are on welding gas bottle sizes and prices — this guide is about which buying model costs least for how you weld.)
The three ways to get gas in Australia
How it works: You pay an annual rental fee for the cylinder, plus refill charges each time you exchange it.
The numbers:
Best for: Regular users who weld weekly and want the supplier to handle testing, maintenance, and cylinder replacement. If a cylinder goes out of test date, it's the supplier's problem.
Worst for: Occasional welders. If you weld once a month, you're paying $80–$120 a year in hire fees for a cylinder sitting in your shed doing nothing.
How it works: You buy a cylinder outright (one-time cost), then exchange it for a full one at a reduced "swap" price each time.
The numbers:
Best for: Hobbyists and occasional welders who go through fewer than 4 refills a year. No ongoing rental fees means you only pay when you actually use gas. Bunnings' Coregas Trade N Go range is this model with a deposit instead of a purchase — see does Bunnings sell welding gas? for exactly what it stocks and at what price.
Worst for: High-volume users. The swap price per litre is higher than the hire+refill price, so heavy users pay more over time.
How it works: You own the cylinder and just pay for the gas to be refilled, but this requires finding a supplier who will refill your cylinder (many will only do their own).
The numbers:
Best for: High-volume users who plan ahead and can wait a day for refills.
Worst for: Everyone else. The savings per refill are small and the inconvenience is real.
- D-size argon mix: ~$100–$130 per refill + $80–$120 annual hire
- G-size argon mix: ~$150–$200 per refill + $120–$180 annual hire
- Deposit: usually none (the cylinder belongs to the supplier)
- Buy D-size cylinder: $250–$350 one-time
- Swap D-size: $80–$110 per exchange
- No annual fees
- Cylinder testing is your responsibility after the initial period
- Buy cylinder: same as swap-and-go
- Refill: $70–$100 (cheapest per-litre option)
- Must wait for your cylinder to be refilled (not instant swap)
The maths nobody shows you
Here's the annual cost comparison for different welding frequencies, using D-size argon mix at typical Australian pricing:
Pretty close. At this frequency, any option works. The differences are within $160/year.
*First year only (includes bottle purchase). Subsequent years: $380 and $340 respectively.
Year 1: hire is cheapest. Year 2+: owning is significantly cheaper.
At this frequency, hire is the worst option by far. You're paying $100/year in rental for the privilege of buying gas. That's a 50% premium on your total cost.
| Method | Annual cost |
|---|---|
| Hire ($100 annual + 2 × $115 refill) | $330 |
| Swap-and-go (year 2+: 2 × $95 swap) | $190 |
| Own + refill (year 2+: 2 × $85 refill) | $170 |
The cylinder size trap
Here's where it gets genuinely confusing for beginners: cylinder sizes are measured in water capacity, not gas volume.
A "D-size" cylinder has about 10 litres of water capacity, which translates to approximately 1,700–2,000 litres of free gas (argon-mix/">argon mix) at standard temperature and pressure. An "E-size" has about 25 litres water capacity (~4,600 litres free gas). A "G-size" has about 50 litres (~9,500 litres free gas).
But the letter codes aren't standardised between suppliers. A "D" from BOC might be slightly different from a "D" from Supagas. And the actual free gas volume depends on the fill pressure, which can vary.
The only number that matters is the free gas volume on the label. Every cylinder in Australia is required to have its free gas volume marked on it. That's the number you use to calculate how long it'll last and what you're paying per litre.
How long does a cylinder actually last?
This depends entirely on your flow rate and duty cycle:
"Hours of arc time" means actual welding time, not workshop time. If you're welding at a 30% duty cycle (which is typical for hobby work), each hour of workshop time uses about 15 minutes of arc time. So a D-size cylinder gives you about 8 hours of hobby workshop time.
| Cylinder | Free gas | MIG at 14 L/min | TIG at 10 L/min |
|---|---|---|---|
| D-size | ~1,800 L | ~2.1 hours arc time | ~3.0 hours |
| E-size | ~4,600 L | ~5.5 hours | ~7.7 hours |
| G-size | ~9,500 L | ~11.3 hours | ~15.8 hours |
The gas you actually need
For MIG welding mild steel in Australia, the standard is argon-CO2 mix at 92/8 ratio (sometimes called Argoshield or similar brand names). This is what every welding supplier will hand you if you ask for "MIG gas." The material-by-material table with flow rates is in what gas do I need for MIG welding?
Do NOT use:
Do use:
- 100% argon for MIG on steel (it won't penetrate properly)
- Any CO2-containing mix for TIG (it will destroy your tungsten)
- 100% CO2 for thin material (too much spatter and heat)
- 92/8 argon-CO2 for MIG on mild steel
- 100% argon for TIG on everything
- 100% argon for MIG on aluminium (with a spool gun)
The checklist before you go to the gas supplier
1. Check what your welder needs (gas type and connection standard)
2. Know your expected usage (monthly? quarterly? rarely?)
3. Decide hire vs own based on the maths above
4. Ask for the free gas volume (litres, not water capacity)
5. Check if a regulator is included (often it's not — budget $60–$120)
6. Get the right flow rate for your process (MIG: 12–15 L/min, TIG: 8–12 L/min)
Our recommendation
For most Australian hobbyists starting out:
Buy a D-size cylinder with swap-and-go from Supagas or Coregas (usually cheaper than BOC for occasional users). Budget $300–$350 for the cylinder, $85–$95 per swap, and you're set for months of hobby welding.
When you're welding more than once a week, switch to G-size hire with BOC or Supagas. The annual cost difference becomes worth it when you're doing 4+ refills a year.
And consider gasless flux-core wire for your first six months — no gas, no cylinder, no hire maths. Just weld.
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*Gas pricing is indicative and varies by state and supplier. Always check current pricing with your local branch. Free gas volumes cited are typical Australian values — read your cylinder label.*
Frequently asked questions
How much does welding gas cost in Australia?
Refills of argon-CO2 mix cost roughly $100–$140 per D-size bottle and $150–$200 per G-size in Australian capitals, plus annual hire if you rent rather than swap-and-own. Straight CO2 is cheaper per refill; pure argon similar to mix. Budget by litres: mix works out around 2.5 cents per litre.
How long does a gas bottle last when welding?
At a typical MIG flow of 12–15 L/min, an E-size bottle (~4,600 L) gives roughly 5–6 hours of arc time — several weeks of hobby welding — while a G-size (~9,500 L) doubles that and a D-size (~1,800 L) suits occasional repairs. Real-world cylinder life is arc time × flow, so duty cycle decides the calendar: at 30% arc-on, each workshop hour drinks about 250 L.
Argon mix or 100% CO2 — which should I buy?
Buy an argon-CO2 mix for general MIG: cleaner beads, less spatter, better thin-sheet behaviour — and mixes dominate Australian counter sales for good reason. Buy straight CO2 only if cost is critical and your work is thicker steel where its deeper penetration and extra spatter are acceptable.
What gas do I need for MIG welding?
For MIG welding mild steel in Australia use an argon–CO2 mix — 92/8 (Argoshield-style) is the standard. 100% CO2 is the budget alternative with more spatter. For MIG on aluminium or stainless you need straight argon or a specialist mix respectively.
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