About PostKid

Getting a child to write and send a real letter should be a small, happy thing — but it usually stalls on a handful of fiddly questions. How much postage does this need? How many stamps is that? What envelope fits a folded sheet? When will it actually arrive at grandma’s, or at a pen pal on the other side of the world? What time is it there, so a video call doesn’t land at bedtime? Is this letter too long for a little cousin to enjoy reading? None of these are hard, but answering them by hand, every time, is where the magic of snail mail turns into a chore for the grown-up helping out.

PostKid exists to take that fiddly arithmetic off your plate so the writing stays fun. Instead of long articles you have to read end to end, the site is built around a set of small, single-purpose calculators, each aimed at one part of sending a letter. The Postage Calculator estimates what a letter, card, or small package costs to mail from its weight, class, and destination. The Stamp Quantity Calculator turns that postage into the number of whole stamps to stick on, leftover value and all. The Envelope & Paper Size Matcher tells you which envelope fits a sheet once it’s folded, with a simple fold guide. The Mail Delivery Time Estimatorgives a friendly range of days for a letter’s journey, and the Pen-Pal Time-Zone Helper finds the window when two children in different countries are both awake. The Letter Word Count & Reading Time tool checks how long a letter takes to read and whether its length suits a younger reader — handy for parents and for teachers setting a pen-pal assignment.

Beyond the calculators, the blog and learn section cover letter writing, pen pals, postcards, and snail-mail crafts for families and classrooms, and the Postal & Writing Museum is a browsable collection of stamps, post boxes, letters, and writing instruments, with every entry, image, and fact drawn from Wikipedia and Wikimedia Commons.

A few things worth stating plainly. PostKid is an independent site, not affiliated with any postal service, stamp issuer, or stationery brand. It is supported by advertising, which is how the tools stay free with no account required. Every result the tools produce — a postage estimate, a stamp count, an envelope match, a delivery window — is a general, curated estimate for planning and teaching, not an official postal quote. For anything that has to be exact, such as the postage on an important package, confirm the live price at the post office counter or the carrier’s website. If something looks off in a tool or an article, or you think a calculator is missing that would help, the contact page is the place to say so.