What Size Air Tank Do You Need for Air Suspension?
An air tank stores compressed air, so your system doesn't depend entirely on the compressor. With the right size tank, air bags fill in seconds, horns sound at full strength, and the compressor works in short, easy cycles. Choose too small a tank and you'll wait on the compressor. Choose too big and you're carrying weight and taking up space for air you'll never use.
So what size air tank for air suspension do you need? Here's how to choose.
What a tank actually gives you
The number on the tank, such as 1, 3 or 5 gallons, is its internal volume. What matters is how much air you can take out between the compressor's cut-out pressure, when the tank is full, and its cut-in pressure, when the compressor starts again.
A simple way to estimate it is:
Usable air (gallons of free air) ≈ tank size × (cut-out PSI − cut-in PSI) ÷ 14.7
14.7 PSI is atmospheric pressure at sea level. For example, a 3 gallon tank with a pressure switch set to 110–150 PSI:
3 × (150 − 110) ÷ 14.7 ≈ 8.2 gallons of free air before the compressor turns back on.
The same switch on a 1 gallon tank gives about 2.7 gallons, and on a 5 gallon tank about 13.6 gallons. That's the air available for filling bags or blowing a horn before the compressor has to run.
Step 1: What are you running?
A two-bag load assist kit. Each bag only needs a few psi added to level a load, so a small tank is plenty. A 1 gallon tank or a 2 gallon tank gives quick adjustments without much weight. Many load assist owners skip the tank entirely and use a compressor-only air bag compressor kit.
Full air ride. Four bags, larger volumes and frequent height changes use much more air. A 3 gallon or 5 gallon tank keeps height changes quick and saves the compressor from running constantly.
Air horns. Horns use a lot of air in a short time. A larger tank, 3–5 gallons, keeps the horn loud for longer blasts. Check the horn maker's guidance for tank size.
Tire top-ups and air tools. These need a sustained flow. A bigger tank helps, but compressor capacity matters just as much. A 100% duty cycle compressor like the PX07 suits this use.
Step 2: Match the tank to the compressor
The compressor has to refill the tank. A small compressor paired with a big tank will take a long time to fill it, and may overheat if its duty cycle is low.
- PX01 (1.31 CFM, 15% duty at 100 PSI): best with no tank, or a small one
- PX02 (1.5 CFM, 50% duty): suits 1–3 gallon tanks
- PX07 (about 3.5 CFM, 100% duty): handles 3–5 gallon tanks and full air ride
These pairings are a starting point, not a hard rule. If you're unsure, ask us.
Step 3: Check the space you have
Tank shape matters as much as volume. Our tanks come in different shapes for different spaces:
| Tank | Size (L × W × H) | Ports | Weight |
|---|---|---|---|
| 1 gallon | 15.2″ × 4.3″ × 5.1″ | 3 (2 × 3/8″, 1 × 1/4″ NPT) | 3.3 lb |
| 1.5 gallon | 11″ × 7.1″ × 8.3″ | 5 (2 × 3/8″, 3 × 1/4″ NPT) | 4.4 lb |
| 2 gallon "hotdog" | 31.3″ × 4.3″ × 5.1″ | 3 (2 × 3/8″, 1 × 1/4″ NPT) | 5.4 lb |
| 3 gallon | 18.1″ × 7.1″ × 8.3″ | 5 (2 × 3/8″, 3 × 1/4″ NPT) | 6.7 lb |
| 5 gallon, 5 ports | 29.1″ × 7.1″ × 8.3″ | 5 (2 × 3/8″, 3 × 1/4″ NPT) | 9.1 lb |
| 5 gallon, 9 ports | 29.1″ × 7.1″ × 8.3″ | 9 | About 9.5 lb (shipping weight) |
The long, slim 2 gallon tank runs along a frame rail, where a wider tank won't fit. The 3 and 5 gallon tanks are wider, and suit a bed, toolbox or under-body mount.
Step 4: Count your ports
Each connection needs a port: compressor in, air out to the bags, pressure switch, gauge line and drain. A 3-port tank works for simple systems. Choose a 5 or 9-port tank if you're running a switch, a gauge and multiple outputs, so you don't need extra tees and fittings.
Drain your tank
Compressing air squeezes out the moisture it carries, and that water collects at the bottom of the tank. Left there, it can reach your valves and bags, and freeze in winter. Open the drain regularly, more often in humid weather. BOSS tanks rotate in their mounts, so you can keep the drain at the lowest point. If your system has an in-cab controller, a water trap adds extra protection. The BOSS Auto Pressure Controller includes one.
Why aluminum?
BOSS tanks are T6 heat-treated aluminum. They're lighter than steel, and they don't rust inside, so clean air reaches your valves and bags. All six tanks list a 0–170 PSI working pressure and a 400 PSI maximum. The mounting legs adjust, and the barrel rotates, so you can keep the drain valve at the bottom.
Quick sizing guide
| System | Suggested tank |
|---|---|
| Two-bag load assist kit | None (compressor only), 1 gallon or 2 gallon |
| Load assist plus occasional tire top-ups | 2–3 gallon |
| Full air ride | 3–5 gallon |
| Air horns | 3–5 gallon, per the horn maker's advice |
Ready to choose? Browse all aluminum air tanks, or pair one with a BOSS compressor.