Essential Oil Dilution Calculator

Percent dilution, drops, and where the numbers come from

A percent dilution is the share of the final liquid that is essential oil. One percent means 1 mL of oil in every 100 mL of liquid. Because oils are sold by the drop, this calculator uses the commonly used approximation of about 20 drops per mL (Tisserand notes drop conversions are always approximate), so a 1% blend in a 16 oz bottle (about 473 mL) needs about 4.7 mL of oil, or roughly 95 drops. Drop size varies with the oil's thickness and the dropper's tip, so treat drop counts as approximate and use a graduated pipette for accuracy.

The Tisserand Institute's adult dilution guidance lists 1 to 3% for body oils and lotions, 0.5 to 1.2% for facial cosmetics and deodorants, and 0.2 to 1% for sensitive or impaired skin, and says to start low and increase only if needed. That is why this page offers 1 to 2% for skin blends. For a room or surface spray with a light scent, many people use about 0.5 to 1%, which is a practical scent level rather than a published safety limit. Some oils have specific maximums, so look up the oil you are using.

Scent is all essential oil adds to a cleaning spray. EPA treats a product that claims to sanitize or disinfect as a pesticide requiring registration, so a homemade mix of oil in water is not an EPA-registered disinfectant, and adding drops to vinegar or water does not turn it into a sanitizer. If you need to kill germs, use a registered product and follow its label. Oils also float on water, so shake the bottle, and store the spray in glass or a compatible bottle, since some oils may degrade plastics.

Safety around pets and children deserves care. The Merck Veterinary Manual calls tea tree oil the most frequently reported essential oil poisoning in companion animals, and lists tea tree, pennyroyal, cinnamon and cassia among oils that can injure the liver and wintergreen, eucalyptus and others among oils linked to seizures. Cats are especially vulnerable because they lack an enzyme that helps clear some plant compounds and they groom themselves. Keep diffusers and sprays out of rooms where pets cannot leave, and never put oil on a pet unless a vet directs. Do not swallow essential oils. Keep bottles capped and out of reach of children, and call Poison Help at 1-800-222-1222 after any ingestion.

Where these numbers come from

The formulas and default values in this calculator are based on:

• Tisserand Institute, Dilution for essential oils (body oils 1-3%, face 0.5-1.2%, sensitive skin 0.2-1%, drop conversions approximate)
• Merck Veterinary Manual, Toxicoses from Essential Oils in Animals
• Pet Poison Helpline, Tea Tree Oil Is Toxic To Dogs
• US EPA, Determining If a Cleaning Product Is a Pesticide Under FIFRA (sanitize or disinfect claims require registration). Note: about 20 drops per mL is a commonly used approximation and varies by oil and dropper

This is general household-cleaning guidance and planning math, not medical or professional advice. Product formulas change, so the label on your bottle always wins: follow its directions and warnings, test a hidden spot first, and never mix cleaning products. For a poisoning emergency call Poison Help at 1-800-222-1222 (US), or 911 if someone has trouble breathing.