4ml Tank Capacity – What is it in Vaping?

Definition

4ml Tank Capacity refers to the maximum volume of e-liquid a vape tank can legally hold under Australian regulations. This 4-millilitre limit balances extended vaping sessions with portability, allowing most users a full day of moderate vaping before refilling. The capacity is measured to the top fill line, excluding any space occupied by the coil, chimney or mouthpiece. Tanks labelled “4 ml” are TPD-compliant and popular among mouth-to-lung and restricted-direct-lung vapers who prefer fewer refill interruptions while staying within national limits.

Technical Details

Internally, a 4 ml tank is engineered with a glass or PCTG tube seated in a stainless-steel or aluminium chassis. The e-liquid surrounds the central chimney and coil assembly; when the coil saturates, capillary action draws juice through wicking ports. Typical 24 mm diameter tanks yield 4 ml by extending height to 35–40 mm, whereas bubble glass versions reach 4 ml at shorter heights by flaring to 27–28 mm. Variants include top-fill slide caps, threaded caps and silicone-stoppered side ports. Most accept universal Thread“>510 Thread coils ranging 0.15–1.2 Ω, pairing nicely with single-Battery“>18650 Battery, 21700 Battery or dual-battery mods. Empty weight averages 45 g; filled weight adds ≈5 g per ml.

Usage & Tips

• Prime new coils with 5–7 drops directly on cotton before assembly to prevent dry hits.
• Keep tank at least one-third full; this maintains wick saturation and avoids burnt puffs.
• When switching flavours, vape until nearly empty, rinse with warm water, air-dry and refill to avoid ghosting.
• Store upright in hot cars; 4 ml of liquid can leak through airflow slots if left sideways at high temperatures.
• High-strength nic salts (20–50 mg) in a 4 ml tank deliver many sessions—track intake to avoid overconsumption, especially if you also use Nicotine“>0mg Nicotine juices for tricks.

History & Context

Before 2017 Australian imports often featured 5–8 ml tanks. When the EU’s Tobacco Products Directive capped capacity at 2 ml, manufacturers released “TPD” versions while exporting larger glass to open markets. Australian vapers imported these, but customs occasionally seized them. Local vendors then standardised 4 ml as a practical compromise—large enough for day-long vaping, small enough to satisfy state health departments—and most 2020+ sub-ohm kits ship with 4 ml bubble glass in the box.