How do you calculate postage for wedding invitations?

Calculating postage is straightforward if you follow a few steps. First, assemble one complete invitation exactly as you will send it, including the invitation card, any response card, a map, and the outer envelope. Then weigh it on a kitchen scale or at the Post Office. Next, measure the length, width, and thickness of the envelope. Royal Mail has two main categories for letters: standard letter and large letter. Standard letters have a maximum size and weight, and large letters are bigger or heavier. If your invitation fits within standard letter limits, you pay the standard letter rate. If it is larger or heavier, you pay the large letter rate. You can check the current limits and prices on the Royal Mail website or ask at the Post Office. They will weigh it for you for free. Remember that square envelopes are often classed as large letters. Also, if you add ribbon, wax seals, or other decorations, the weight and thickness increase, so recalculate. Always round up if you are close to a weight limit.