The quick answer: The most reliable way to sterilise glass jars and bottles at home is to boil them in a pan of water for 10 minutes. A hot dishwasher cycle with no detergent also works, and many UK cooks use the oven at 160°C (gas mark 3, or 140°C fan) for 15 minutes. Sterilise shortly before you fill, and fill while the jars are still warm.

Clean, sterilised jars are the first rule of making jam, chutney, pickles and bottled drinks that keep. Sterilising kills the bacteria, yeast and mould that cause spoilage, which washing alone does not. This guide covers each method with times and temperatures, how to treat lids and seals, how to fill jars safely, and answers to the questions we hear most.

Which method should you use?

Method Setting Time Notes
Boiling water Rolling boil 10 minutes Best all-rounder for jars and bottles
Dishwasher Hottest cycle, no detergent Full cycle Hands-off. Time it to finish when you are ready to fill
Oven 160°C (140°C fan, gas 3) 15 minutes Good for large batches. Remove rubber seals first
Microwave Full power, jar half-filled with water 1 to 2 minutes Small jars only, no metal lids.
Air fryer About 120°C 10 to 15 minutes Small jars only. A quick option for a small batch

Before you start

  • Check the glass. Do not use jars or bottles with chips or cracks. Damaged glass can break when heated.
  • Wash first. Wash jars, bottles and lids in hot soapy water and rinse. Sterilising works on clean glass, not dirty glass.
  • Keep temperatures close. Pouring hot preserve into cold glass, or cold liquid into hot glass, is the usual cause of cracking. Keep jars warm until you are ready to fill them.
  • Do not pour boiling water into jars. Do not sterilise by pouring boiling water into jars or bottles. Bring the water to the boil with the jars in it instead.

How do you sterilise jars?

1. Boiling water

The simplest and most popular method

  1. Stand the washed jars in a large pan, on a rack or folded tea towel so they do not knock together.
  2. Cover the jars completely with cold water.
  3. Bring to the boil and keep at a rolling boil for 10 minutes.
  4. Cover and keep the jars warm until you are ready to fill them.

2. In the dishwasher

A good hands-off method if your machine reaches a high temperature.

  1. Place clean jars and bottles on the top rack. Take off any rubber seals.
  2. Choose the hottest cycle and use hot water only, with no detergent or cleaning product.
  3. Time the cycle to finish just as you are ready to fill, and leave the jars in the closed machine until then.

3. In the oven

Widely used by UK cooks for large batches; befpre ypu do this, make sure your oven is clean.

  1. Wash the jars and bottles, then leave them wet.
  2. Stand them on a baking tray and heat at 160°C (gas mark 3, or 140°C fan) for 15 minutes.
  3. Turn the oven off and leave the jars inside, warm, until you are ready to fill them.

Remove rubber seals before the jars go in, as the dry heat can crack them. Always use oven gloves, as the glass will be very hot.

4. In the microwave

Possible for a very small batch or a single small jar, but we suggest boiling or the dishwasher if you are preserving anything for months.

  1. Wash the jar and half-fill it with water.
  2. Microwave on full power for 1 to 2 minutes, until the water boils.
  3. Carefully pour out the hot water.

Never put metal lids in the microwave. Bottles generally do not fit.

5. In the air fryer

Air fryers are popular for sterilising small batches of jars that you will fill straight away.

  1. Wash the jars but do not dry them.
  2. Preheat the air fryer to about 120°C.
  3. Place the jars inside with space between them and heat for 10 to 15 minutes.

Use only jars that fit without touching the heating element or each other. For preserves you want to keep for months, boiling or the dishwasher is the safer choice.

How do you sterilise glass bottles?

Glass bottles are sterilised the same way as jars, but their narrow necks need extra attention:

  • Boiling: Stand the bottles in a pan, fill them with water so they do not float, cover with water and boil for 10 minutes.
  • Dishwasher: A hot cycle works for upright bottles. Check the neck is rinsed through.
  • Oven: Stand bottles upright on a tray at 160°C (140°C fan) for 15 minutes.
  • Microwave: Not suitable, as most bottles will not fit.
  • Brush first. Use a bottle brush to clean the inside, shoulders and base before sterilising.
  • Fit the closure last. Put corks, swing tops or screw caps on only after the bottle is filled. See our range of glass bottles and lids and closures.

Cold liquid in hot glass can crack it, so let freshly sterilised bottles cool a little if you are filling them with a cold drink.

How do you sterilise lids and rubber seals?

Lids need the same care as the jars.

  • Metal twist-off and vacuum seal lids: Kilner advises simmering lids and seals in a small pan of water at around 82°C for 10 minutes rather than a hard boil, which can damage the sealing compound. Keep them covered until you are ready to seal.
  • Rubber rings and seals: Remove them before the jar goes in the oven, and simmer them separately for 10 minutes.
  • Dishwasher: Lids can go through on the hottest cycle alongside the jars.
  • Plastic lids: Follow the lid maker’s instructions rather than boiling.

Browse our lids and closures to match the right lid to your glass jars.

How to fill sterilised jars safely

  1. Keep them clean. Hold jars by the outside. Do not touch the inside or the rim.
  2. Fill while warm. Pour hot preserve into warm jars. This reduces cracking and helps form a good seal as the contents cool.
  3. Mind the rim. Wipe away any drips from the rim before you seal.
  4. Leave a small gap. Leave about 1 cm of space at the top.
  5. Seal straight away. Put the lid on while the contents are still hot. Some traditional preserves are covered instead with a wax disc and cellophane.
  6. Remove air bubbles. For chunky chutneys and jams, tap the jar gently on the worktop before sealing.

Time the job so the jars are ready when the preserve is. Start sterilising when your preserve has about 20 minutes left to cook, so jars and contents are both hot at the same time.

Frequently asked questions

How long do you sterilise jars for?

Boil them for 10 minutes. In the oven, 160°C (140°C fan) for 15 minutes is the usual UK guidance. A hot dishwasher cycle takes the length of the cycle.

Can you sterilise jars in an air fryer?

Yes, for small jars. Heat washed jars at about 120°C for 10 to 15 minutes with space between them. Use boiling or the dishwasher for preserves you plan to keep for months.

Can you sterilise jars in the microwave?

Yes, for small jars without metal lids. Half-fill the jar with water and microwave on full power for 1 to 2 minutes until the water boils, then pour it out carefully.

Can you sterilise jars in the dishwasher?

Yes. Use the hottest cycle, hot water only with no detergent, and leave the jars inside until you are ready to fill them. Jars will not be properly sterilised on an eco or low-temperature cycle.

How long do sterilised jars stay sterile?

Not long. Sterilise jars shortly before you fill them and keep them warm and covered in the meantime. Once they cool and are exposed to air or handled, they are no longer sterile.

How do you sterilise glass bottles for homemade drinks?

Wash them, then boil them in a pan of water for 10 minutes, or use a hot dishwasher cycle. Clean the inside with a bottle brush first, and add the cap or cork only once the bottle is filled.

Do you need to sterilise jars for jam?

Yes. In UK home preserving the usual advice is to sterilise jars for jam, chutney and pickles and to fill them while warm. The US National Center for Home Food Preservation says pre-sterilising is not needed when filled jars are then processed in a boiling water bath for 10 minutes or more. That is a different method from hot-filling jam, so follow your recipe.

Do you need to sterilise new jars?

Yes. New jars are clean from the factory but not sterile, so wash and sterilise them before filling.

Can you sterilise glass milk bottles?

Yes. Rinse them well, then boil for 10 minutes or use a hot dishwasher cycle, as for any other glass bottle.

How do you sterilise jars without boiling?

Use the dishwasher (hottest cycle, no detergent) or the oven at 160°C (140°C fan) for 15 minutes. The microwave also works for single small jars, but is less reliable.

Need jars and bottles to sterilise? Browse our glass jars, glass bottles and lids and closures.