People planning to send presents and Christmas cards over the next few weeks may want to note these key dates for Royal Mail deliveries.

Britons have been urged to send off their items as soon as they can to make sure they arrive in time for Christmas Day.

These are the last dates for sending post in time for Christmas and how much it could cost, according to Royal Mail.

Second class Christmas deadline - December 18

Any letters or parcels with second-class stamps should be sent off by December 18. The cost of a second class stamp increased from October 2, now costing 75p.

Standard and large letters using this can weigh up to 100g, while large letters can weigh up to 750g using other stamps.

Standard-sized letters can be no larger than 24cm x 16.5cm x 5mm and large letters can be no bigger than 35.3cm x 25cm x 2.5cm.

Letters sent through the ‘Signed For’ service, which is not tracked, will cost £2.25. Sending a large letter through the normal service will cost £1.55.

Parcel costs vary depending on its size and weight, with costs starting at £2.99. The Tracked 48 service costs at least £3.29.

First-class Christmas deadline - December 20

For letters, the cost of a standard-sized delivery is £1.25 while a large letter is £1.95. To upgrade to a ‘Signed For’ service will cost £2.75.

For parcels, the cost is £3.69 to send first class and for the Tracked 24 service, it will cost £3.99. These are starting costs and larger parcels will cost more to send.

Special delivery Christmas deadline - December 21/22

The last day for Special Delivery Saturday service is December 22 but this comes with an extra fee.

The starting price for this service is:

• 100g - £7.35
• 500g - £8.15
• 1kg - £9.45
• 2kg - £12.15
• 10kg - £16.45
• 20kg - £20.45.

These prices are for parcels with compensation covering up to £750. There are higher prices for compensation of £1,000 and £2,500.

Customers can also get an online price for each compensation bracket which is slightly cheaper than these prices. All the prices are available on the Royal Mail website here.

International postage

People who want to send cards or presents abroad will need to post a little earlier. Prices vary depending on where a person is sending items. To find out how much this could cost, a person can check with their local Post Office or through Royal Mail's website here.

These are the deadlines for sending mail to each part of the world:

• December 6 - Australia, the Caribbean, China, Africa, Asia, Central and South America, Far and Middle East and New Zealand
• December 7 - Cyprus and Malta
• December 8 - Greece, Eastern Europe (excl. Czechia, Poland and Slovakia) and Turkey
• December 11 - Canada, Czechia, Finland, Italy, Norway, Poland, Portugal, Sweden, Spain and the United States
• December 13 – Austria, Belgium, Denmark, France, Luxembourg, Germany, Iceland, Ireland, Netherlands, Slovakia and Switzerland.

For the latest personal finance news, follow us on Twitter at @ExpressMoney_.