How Many Stamps Do You Need? Exact Stamps For Letters/Large Letters & Parcels


Working out exactly how many stamps you need to send a parcel or letter can be a confusing process.

If you’re sending a standard-sized letter that weighs less than 1oz then you will need a single forever stamp. If it weighs more it will cost an additional 15¢ for every extra ounce.

A large A4 Letter (also known as a Flat) weighing up to 1oz will need one 1 x Standard Forever Stamp, 1 x 10¢ stamp & 1 x Postcard stamp. For each additional ounce of weight it will cost 20¢ more to post.

To work out exactly how many stamps you need you will need to know:

  • The size of your letter, flat or parcel.
  • The weight in ounces.
  • The address you are sending your parcel or letter to.

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How Many Stamps Do You Need To Send A Letter In The U.S?

Letter WeightStamps Required (Cheapest Option)CostStamps Required (Fewest Stamps)Cost
<1oz1 x Standard Forever Stamp.$0.551 x Standard Forever Stamp.$0.55
2oz1 x Standard Forever Stamp & 1 x 15¢ Additional Ounce stamp.$0.701 x Standard Forever Stamp & 1 x 15¢ Additional Ounce stamps$0.70
3oz1 x Standard Forever Stamp & 2 x 15¢ Additional Ounce stamps.$0.852 x Standard Forever Stamps$1.10
3.5oz1 x Standard Forever Stamp, 1 x Postcard stamp & 1 x 10¢ stamp.$1.002 x Standard Forever Stamps.$1.10

As of January 2019 a first-class stamp costs $0.55, every additional ounce is charged at $0.15. So if you are sending a 2-ounce letter you will need $0.70 worth of postage stamps.

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How many stamps do you need to send a letter in the U.S

How Many Stamps Do I Need For A Postcard In The U.S?

Postcards come in a standard size of 6″ x 4-1/4″ these can be posted anywhere in the U.S using one Postcard stamp at a cost of $0.35.

If your postcard is larger than the standard size then, providing it is no larger than 11-1/2″ x 6-1/8″ & 1/4″ thick you can post it using a single Forever stamp at a cost of $0.55.

How Many Stamps Do You Need To Send A Large Letter (Flat / A4 Envelope) In The U.S?

A flat is an item of mail that is either:

  • wider than 6 & 1/8 inches on the short side.
  • longer than 11 1/2 inches on the longer side.
  • more than 1/4 of an inch thick.

They are often used for important A4 documents that you don’t want to be folded or damaged in the post. Postage costs for flats are higher than for standard letters:

Flat WeightStamps Required (Cheapest Option)CostStamps Required (Fewest Stamps)Cost
<1oz1 x Standard Forever Stamp, 1 x 10¢ stamp, and 1 x Postcard stamp.$1.001 x Standard Forever Stamp, 1 x 10¢ stamp, and 1 x Postcard stamp.$1.00
2oz2 x Standard Forever Stamps & 1 x 10¢ stamp.$1.202 x Standard Forever Stamps & 1 x 10¢ stamp.$1.20
3oz2 x Standard Forever Stamps & 2 x 15¢ Additional Ounce stamps.$1.403 x Standard Forever Stamps.$1.65
4oz2 x Standard Forever Stamps, 1 x 15¢ Additional Ounce stamp & 1 x Postcard stamp.$1.603 x Standard Forever Stamps.$1.65
5oz3 x Standard Forever Stamps and 1 x 15¢ Additional Ounce stamp.$1.803 x Standard Forever Stamps and 1 x 15¢ Additional Ounce stamp.$1.80
6oz3 x Standard Forever Stamps & 1 x Postcard stamp.$2.003 x Standard Forever Stamps & 1 x Postcard stamp.$2.00
7oz4 x Standard Forever Stamps. $2.204 x Standard Forever Stamps. $2.20
8oz4 x Standard Forever Stamps, 1 x 5¢ stamp, & 1 x 15¢ Additional Ounce stamp.$2.405 x Standard Forever Stamps. $2.75
9oz4 x Standard Forever Stamps, 1 x 5¢ stamp, & 1 x Postcard stamp.$2.605 x Standard Forever Stamps. $2.75
10oz5 x Standard Forever Stamps & 1 x 5¢ stamp.$2.806 x Standard Forever Stamps. $3.30
11oz5 x Standard Forever Stamps, 1 x 10¢ stamp, & 1 x 15¢ Additional Ounce stamp$3.006 x Standard Forever Stamps. $3.30
12oz5 x Standard Forever Stamps, 1 x 10¢ stamp, & 1 x Postcard stamp$3.206 x Standard Forever Stamps. $3.30
13oz6 x Standard Forever Stamps & 1 x 10¢ stamp.$3.406 x Standard Forever Stamps & 1 x 10¢ stamp.$3.40

A flat weighing 1oz will need one 1 x Standard Forever Stamp, 1 x 10¢ stamp and 1 x Postcard stamp. For each additional ounce of weight it will cost 20¢ more to post your flat.

Be aware that prices may vary depending on where you buy your stamps from.

How Many Stamps Do I Need To Send A Parcel In The U.S?

Calculating the number of stamps required for a parcel is a bit more complicated than it is for letters.

This is because parcel postage is charged by weight and size of the parcel as well as the distance it is travelling.

Parcels are usually too big to deposit in a mailbox so you will have to take it to the post office to get in despatched in which case it is easiest to ask them to sort the postage for you.

However if you want to know how much you will be expected to pay, or you want to print your own postage label, then you can use the United States Postal Service postage calculator.

To use the United States Postal Service postage calculator follow these steps:

  1. Enter the destination country and zip code in the drop-down box.
  2. Confirm the date and time you will be sending it.
  3. Tick to confirm if you are sending any live animals, day-old poultry or hazardous materials.
  4. Select which type of shipment you wish to use; Flat Rate Postcard, Flat Rate Envelopes, Flat Rate Boxes or you can find the price based on shape and size.
  5. You will now be given the price for your requested shipping options  – select “display all options” at the top to compare costs for other shipping options.
  6. You can then choose to add extra options including Certificate of Mailing, Insurance, Registered Mail etc.
  7. The next step will show you your final shipping cost.
  8. If you haven’t selected any extras then you can just calculate how many stamps you will need to cover the shipping cost.
  9. If you have added extra options you will need to get a shipping label printed either at a post office or you can print one yourself via the USPS Click & Ship page.

How Many Stamps Do I Need To Send A Letter In The UK?

If you live in the U.K and are mailing to a U.K address then postage rates are worked out by a flat rate based on weight.

The table below shows how many stamps you will need based on the weight of your letter.

Letter WeightNumber Of Stamps – 1st classCostNumber Of Stamps – 2nd classCost
Letter*  – 100g or less1£0.761£0.65
Large Letter** 100g or less2£1.522£1.30
Large Letter** 101g – 250g2£2.282£1.30
Large Letter** 251g – 500g3£2.283£1.95
Large Letter** 501g – 750g4£3.044£2.60

* Letter may incur extra charges if they exceed dimensions of 24cm x 16.5cm x 0.5cm.

How Many Stamps Do I Need To Send A Parcel In The UK?

Postage cost for parcels in the UK is based on both their size and their weight. They fall into three size categories; small, medium and large.

Small parcels should measure no more than 45cm (L) x 35cm (W)x 16cm (D):

Small Parcel WeightNumber Of Stamps – 1st classCostNumber Of Stamps – 2nd classCost
<1kg6£4.565£3.25
1kg – 2kg8£6.085£3.25

Medium parcels should measure no more than 61cm (L) x 46cm (W)x 46cm (D):

Medium Parcel WeightNumber Of Stamps – 1st classCostNumber Of Stamps – 2nd classCost
< 1kg9£6.849£5.85
1kg – 2kg13£9.889£5.85
2kg – 5kg23£17.4823£14.95
5kg – 10kg32£24.3234£22.10
10kg – 15kg48£36.4847£30.55
15kg – 20kg48£36.4847£30.55

Large parcels should measure no more than 150cm (L) and their total length, width and depth should be less than 3m.

The Royal Mail will not post Large parcels as they are not equipped to do it, they have to be sent via Parcelforce.

You will need to get a custom price from the Parcelforce website.

To do this follow these steps:

  1. Head to the Parcelforce website.
  2. Input the ‘from’ and ‘to’ postcodes.
  3. Input the parcel weight.
  4. Input the parcel dimensions.
  5. Click get quote.

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