• mg/ml – Milligrams of nicotine per milliliter of liquid. The standard way to express strength.
• Nicotine base – A concentrated nicotine solution, usually in PG or VG, that you add to e-liquid.
• Freebase nicotine – The standard form of nicotine; harsher at high strengths.
• Nicotine salts – A smoother form of nicotine, often used in higher-strength products.
• PG/VG – Propylene glycol and vegetable glycerin, the two main carriers in e-liquid.

That's bottle math in a nutshell. It's not rocket science—it's multiplication and subtraction. Use the Windbar E-liquid Calculator to make it even easier, and you'll never worry about a wrong batch again.

For more context on choosing the right strength for your customers, see the Nicotine Strength Buying Guide: What Distributors Need to Check Before Ordering. And if you're curious about how PG/VG ratios affect your mixes, the VG/PG Ratio Explained article has you covered.