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Free tool · No sign-up · Based on ASA / ESAIC guidance

Surgery Fasting Calculator

Enter your surgery arrival time and get the exact times to stop solid food, light meals, milk, and clear liquids — plus notes for your situation.

We calculate from your hospital arrival time — not the exact start of anesthesia. Because anesthesia usually begins 1–2 hours after you arrive, anchoring to arrival builds in a safety margin. Always also follow your hospital's own instructions.

Calculator inputs

Anything that applies? (optional — adds notes)

The fasting window at a glance

How the hours before surgery break down for a typical adult.

Light meal toast, tea + milk Clear liquids only water, black coffee, pulp-free juice Nothing by mouth ← Before 8h: eat & drink normally 8 hrs before 6 hrs before 2 hrs before Surgery arrival
The standard adult fasting window (ASA / ESAIC). Your hospital may differ — use the calculator above for your exact times.

What counts as a clear liquid?

✓ Allowed (clear)

  • Water
  • Black coffee or tea (no milk or cream)
  • Apple juice & pulp-free juice
  • Clear sports drinks (if your hospital allows)

✕ Not allowed

  • Milk, cream & smoothies
  • Juice with pulp
  • Anything you can't see through
  • Chewing gum & hard candy

Want everything in one place?

Build your full surgery plan — these fasting times plus your medicines, a dated countdown, what to bring, the questions to ask and your recovery dates — on one printable page.

Build my surgery plan →
Medically reviewed by Dr. Saurabh Shukla, MBBS, DNB Anesthesiology · Last updated June 2026

Frequently asked questions

Can I drink water before surgery?

Yes. Clear liquids such as water, black coffee, apple juice, and pulp-free juice are usually allowed up to 2 hours before your hospital arrival time, unless your team tells you otherwise.

Can I drink black coffee before surgery?

Usually yes — black coffee with no milk or cream counts as a clear liquid and is generally allowed up to 2 hours before your hospital arrival time. Adding milk or cream makes it a food.

Can I chew gum before surgery?

No. Chewing gum stimulates stomach acid and saliva and can increase aspiration risk under anesthesia. Avoid gum, mints, and hard candy during your fasting window.

What if I accidentally ate or drank inside the window?

Don't hide it — call your surgical team right away. They would rather reschedule than risk aspiration. Be honest about exactly what and when.

Can I take my morning medicines before surgery?

Many essential medicines are taken as usual with a small sip of water — but some must be held. Confirm your personal list with your pre-op team and see our medications guide.

Is fasting different for children?

Yes. Infants and toddlers have separate timings for breast milk (about 4 hours) and formula or cow's milk (about 6 hours). Choose the child or infant option in the calculator.

Is fasting different if I have diabetes?

The fasting times are similar, but you must plan how to adjust diabetes medicines and insulin and monitor your blood sugar. Ask your team for a specific plan.

Is fasting different if I take Ozempic or another GLP-1?

Possibly. GLP-1 drugs slow stomach emptying. Current multi-society guidance says many patients can continue them before elective surgery, with high-risk patients managed individually (for example a 24-hour clear-liquid diet). Tell your team you take one.