About StowMath

What this site is

StowMath is a library of free calculators for freight and logistics arithmetic - the maths that sits between a supplier quote and a number you can actually make a decision on. Cubic volume, chargeable weight, landed cost, cost per unit, and more being added.

Everything runs in your browser. There is no account, no signup, no paywall, and nothing you type is sent anywhere.

Why it exists

Most freight calculators on the web have the same two problems. They accept one carton size when a real packing list has five. And they hand you a number with no working, no assumptions, and no indication of where the constants came from - which means you cannot check it, and you cannot tell your forwarder how you got there.

The second problem is the serious one. A courier divisor or a duty basis buried inside someone's JavaScript is a number that was true on the day it was written and has been quietly wrong ever since. StowMath either makes that kind of value an input you control, or it names the published source it came from and the date it was last checked.

Who is behind this

Masoom Khan

Builds and maintains StowMath

StowMath is built and maintained by Masoom Khan, a master's student working on it in the open alongside studying. One person, no company behind it, no team - which is worth saying plainly rather than hiding behind a plural "we".

That shapes what this site claims. It does not ask you to trust an author's years in freight forwarding, because there are none to point at. It asks you to check the arithmetic, which is printed under every result, and to supply the commercial values yourself - the courier divisor, the duty rate, the tariff basis - because those belong to your carrier and your broker, not to a stranger's calculator. Where a page does depend on a published figure, the source is named and dated at the bottom of it. That standard is the entire reason this site is worth using, and it does not require a CV.

If a number on this site looks wrong to you, it might be. The contact page has a real email address on it, and a reported error gets fixed and dated rather than argued with.

The standards every tool has to meet

These are not aspirations. A tool does not go live until all of them hold:

• The working is always shown. Every result displays the arithmetic that produced it, so you can check it line by line and paste it into an email.
• Real-world constants are never invented. Courier divisors, container dimensions, freight class bands and duty bases are published values. Each one is either an input you control or is cited with its source and the date it was checked.
• Assumptions are stated, including the awkward ones. Where a calculation depends on a jurisdiction, a carrier practice, or a simplification, the page says so instead of hiding it.
• Every page is dated. If a page has not been reviewed recently, you can see that.
• No result is ever fabricated. Empty, negative or nonsensical input produces an empty state, never a plausible-looking wrong number.

How it is built

A static site - plain HTML, CSS and a few kilobytes of JavaScript per page, with no framework, no analytics on your inputs and no backend. That is a deliberate choice rather than a limitation: a calculator that runs entirely on your machine cannot leak a shipment you have not announced yet, and it stays fast on a bad connection in a warehouse.

Read the privacy policy for exactly what that means in practice, and the disclaimer for what these results should and should not be used for.