Advertisement feature — this page is published by Scentech.
Guide 2026 · updated 10 September 2026
Aromatherapy oil diffuser: which oil to choose, and how to use it
Which scent suits the evening, your working day or a fresh home, what oil costs per millilitre, and which device belongs with which oil.
Contents
In short
The short answer, then the detail.
Eveninglavender, cedar or sandalwood — soft and woody
Worklemon, grapefruit or rosemary — bright, not sweet
Fresh homeeucalyptus, green tea or mint — clean and green
essential oil belongs in a water diffuser, fragrance oil in a cold-air diffuser; never mix the two up
Which scent for which moment
Four moments people switch a diffuser on for, with the notes that suit them.
Evening and winding down
lavender
cedar
sandalwood
vanillaSoft, woody or lightly sweet; often chosen once the lights go low. Sharp citrus feels out of place then; a heavy base note lingers.
usual guideline3–5 drops per 100 ml water (ultrasonic) · 20–60 minutes per session
Work and focus
lemon
grapefruit
rosemarypeppermintBright and light, citrus and herbs without a sweet base. Keep it low; short sessions keep the scent noticeable.
usual guideline3–5 drops per 100 ml water (ultrasonic) · 20–60 minutes per session
Fresh home
eucalyptus
green tea
bergamotmintGreen and clean, the scent people reach for after cooking or cleaning. Works well in a hallway, kitchen or bathroom.
usual guideline3–5 drops per 100 ml water (ultrasonic) · 20–60 minutes per session
Guests and living room
jasmine
rose
orange blossom
white teaFloral or softly ambery, noticeable without becoming heavy. Switch it on an hour before guests arrive, off afterwards — scent reads stronger in a full room.
usual guideline3–5 drops per 100 ml water (ultrasonic) · 20–60 minutes per session
How to read a scent
Top, heart and base.
Top note
What you smell first: citrus, herbs, mint. Light and fleeting, mostly gone after fifteen minutes.
Heart note
The character of the scent: florals, tea, spice. Lingers for hours.
Base note
What remains: wood, amber, musk, vanilla. Heavy and warm, it carries the rest.
- the first quarter hour
- the hours after that
- the whole evening
A good evening oil has a heavy base; a working-day oil has a light top note.
The difference between essential oil and fragrance oil
Essential oil | Fragrance oil (aroma oil) | |
|---|---|---|
| what it is | pure plant extract, one plant per bottle | a blended scent with several notes |
| price per ml | €0.60–1.50 per mlDutch retail, bol.com, September 2026 | €1.73–2.40 per ml, looseDutch retail, September 2026 |
| device | ultrasonic water diffuser or nebuliser | cold-air diffuser or reed diffuser |
| how long it lasts | short: 20–60 minutes per sessionusual guideline | long: hours to months per fillmanufacturer figures |
| note | dilute; never apply undiluted to skin; ventilate if you have pets | only in the device it's made for, never in water |
Choose the oil to match the device you own, not the other way round.
Which device for which oil
Choose your oil; that leaves two devices.
Have essential oil?
pure plant extract
Ultrasonic diffuser
- which oil
- in water
- upkeep
- empty and dry the tank daily, US EPA advice
- reach
- 10–35 m² where brands state it
- cost
- €0.60–1.50 per ml
suitseveningwork
Nebuliser
- which oil
- undiluted, no water
- upkeep
- rinse the glass reservoir
- reach
- usually not stated
- cost
- €0.60–1.50 per ml
suitsworkguests
Have fragrance oil?
blended scent
Reed diffuser
- which oil
- on reeds
- upkeep
- turn the reeds weekly
- reach
- the spot where the bottle sits
- cost
- about €10 per month, 250 ml over three months
suitsfresh homeguests
Cold-air diffuser
- which oil
- oil or a pod, no water
- upkeep
- swap the pod or bottle, no water
- reach
- up to 40–100 m² according to manufacturers
- cost
- €0.46–2.40 per ml
suitsfresh homeguests
How to use an aromatherapy oil diffuser
Step 1: Choose the oil for the moment
Start with the moment, not the bottle: woody notes such as cedarwood for the evening, citrus such as bergamot for a working day, green notes such as eucalyptus for a fresh home.
Step 2: Measure it out
In a water diffuser, add 3–5 drops of essential oil per 100 ml of water, a usual guideline from manufacturers. In a cold-air diffuser or on reeds, the fragrance oil or pod goes in undiluted, without water.
Step 3: Set the time
Run the diffuser for 20–60 minutes per session, then take a break. Choose the low setting in a small room; don't leave it running all night.
Step 4: Clean it
Pour out the water and dry the tank after every use; the US EPA recommends this daily. Clean it weekly with a splash of vinegar against limescale. With a cold-air diffuser, swap the pod after 1–3 months, no water needed.
Questions
Can fragrance oil go in an ultrasonic diffuser?
No, manufacturers advise against it: fragrance oil dissolves poorly in water and can damage the plastic. It goes undiluted into a cold-air diffuser or onto reeds.
How many drops of oil go in a diffuser?
The usual guideline is 3–5 drops of essential oil per 100 ml of water: nine to fifteen for a 300 ml tank. Too faint? Use a larger diffuser, not more drops.
How long can a diffuser run for?
For water diffusers, 20–60 minutes per session with a break is the usual guideline. Cold-air diffusers use timed schedules; choose the low setting in a small room.
Is a diffuser safe around cats and dogs?
Take care: ventilate the room, leave a door open so the animal can leave, and use less oil for shorter sessions. If in doubt, ask your vet.
What does scent cost per month?
Essential oil costs €0.60–1.50 per ml, loose fragrance oil €1.73–2.40 per ml. Reed diffusers work out at roughly €10 per month, a candle at €0.44–0.59 per hour burnt.
Prices bol.com and rituals.com (Dutch retail), September 2026
What is the difference with reed diffusers or a candle?
Reed diffusers need no power, but only scent the bottle's location; turn them weekly. A candle gives warmth and light, with an open flame, for three to four hours. A diffuser has a timer and a stated reach in square metres.
Further reading
Where to buy fragrance oil
Essential oil chemist, health shop, bol.com; €0.60–1.50 per ml (Dutch retail, September 2026)
Loose fragrance oil home and interior shops, bol.com; €1.73–2.40 per ml (Dutch retail, September 2026)
Fragrance oil as a pod, with a cold-air diffuser Scentech, see below
Scentech sells 26 scents as a pod, without water
A pod holds a blended fragrance oil, not a pure essential oil, for a cold-air diffuser. It ships from the Netherlands; availability and cost for the UK are shown at checkout.
Smart Aroma Diffuser at 5 scents, Diffuser 2 at 7, Pro at 9, only via the offer page; pod price is Shopify's GBP price, September 2026.
Advertisement See the collection at Scentech
4.7 on Trustpilot, 281 reviews (8 September 2026) · 30-day cooling-off period · 1-year warranty
Ready to choose?
Choose the moment first, then the oil, then the device: essential oil in a water diffuser, fragrance oil in a cold-air diffuser. Want fragrance oil without water or counting drops? Scentech has 26 scents as a pod, with a free diffuser from 5 scents via the offer page.
Advertisement See the scents at Scentech
4.7 on Trustpilot, 281 reviews (8 September 2026)