What is sub ohm vaping?

The technical bit, briefly

Coils have electrical resistance measured in ohms (the Ω symbol). When you press fire, the battery pushes current through the coil. The lower the resistance, the more current flows for a given voltage. More current means more heat. More heat means more e-liquid vapourised per second.

Ohm's Law: Current = Voltage / Resistance. With a typical 3.7V battery, a 1.0 ohm coil pulls 3.7 amps. A 0.5 ohm coil pulls 7.4 amps. A 0.15 ohm coil pulls almost 25 amps. The lower the resistance, the harder the battery works.

• Above 1.0 ohm: Standard MTL coils. Lower current, lower power, smaller vapour. The default for ex-smokers and pod kit users.
• Exactly 1.0 ohm: The dividing line. Coils on this boundary work for either style depending on airflow and wattage.
• Below 1.0 ohm (sub ohm): Higher current, higher power, more vapour. Standard for DTL.
• Very low (below 0.2 ohm): Performance sub ohm. Used in cloud chasing. Higher battery demands and lower safety margins.

Why sub ohm changed vaping

When vaping became popular in the early 2010s, most kits were above-ohm and produced modest vapour. Sub ohm coils arrived around 2014 and changed the experience entirely.

Sub ohm kit explained

Sub ohm hardware has specific requirements that standard MTL hardware does not.

• The mod or device: Must support the current draw. Regulated box mods rated 60W or higher are standard. Pod kits with sub-ohm modes are increasingly common.
• The tank or pod: Sub ohm tanks have larger wicking holes to feed thick liquid faster. MTL tanks are not interchangeable.
• The coil: Below 1.0 ohm. Often made with mesh rather than wire to spread heat more evenly. Larger surface area to vapourise more liquid.
• The battery: 18650 or 21700 cells in removable mods. Built-in 2000-5000mAh batteries in pod kits. Drain rate matters: 25A or higher continuous discharge rating for sub ohm.
• The drip tip: Often wider bore to handle larger vapour volume.
• The airflow: Open or adjustable. Sub ohm needs airflow to cool the coil and carry vapour out efficiently.

The right e-liquid for sub ohm

E-liquid for sub ohm is fundamentally different from MTL e-liquid. Mixing them up is the most common mistake new sub ohm users make.

Battery safety in sub ohm

Sub ohm draws significantly more current from the battery than MTL. Most modern regulated mods handle this safely with built-in protections. Mech mods (unregulated) do not have those protections and are dangerous in unskilled hands.

• Regulated mods: Have a chipset that controls voltage and includes safety features: short circuit protection, over-temperature cut-off, low-voltage cut-off, low-resistance lock. Use these unless you are an expert.
• Mech mods: Apply battery voltage directly to the coil with no regulation. The coil resistance and battery limits determine current. Mistakes cause battery venting or thermal events. Only for experienced users with Ohm's Law knowledge.
• Battery condition: Replace removable batteries every 6-12 months of regular sub ohm use. Inspect for wrapper damage, dents and visible leaks. Damaged batteries should be recycled, not used.
• Battery wrapping: The plastic wrapper on a battery is electrical insulation. A torn wrapper can cause a short circuit. Re-wrap or replace immediately.
• Charging: Use a proper external battery charger for removable cells. Built-in charging is usually fine for internal batteries but can be slower and harder on cells.
• Storage: Carry removable batteries in plastic cases, not loose in pockets. Loose batteries can short on metal objects (keys, coins) and overheat dangerously.
• Battery drain rating: Look for batteries rated at 25A continuous discharge minimum for sub ohm. The Samsung 25R, Sony VTC5A and Molicel P26A are common choices.

Sub ohm wattage in practice

Where to set the wattage on a sub ohm coil depends on the coil's rating and your preferences.

The middle of the recommended wattage range is usually the sweet spot. Going lower produces less vapour but better coil life. Going higher produces more vapour but kills the coil faster.

The bottom line