February 07, 2023
2 min read

micro-dollar: a way to deals with decimal numbers or monetary values


The easiest way to deal with decimal number in our application is "multiply by 1,000,000". such that using 6-digit decimal you won't make a mistake.

For example:

  • USD$1.23 = 1230000 micro USD
  • USD$0.01 = 10000 micro USD

I termed it the "micro-dollar," and we use this approach in almost our services, messaging, contracts as a standard for all monetary values.

Numbers by Mika Baumeister

🔗Why micro-dollar?

The benefits of this micro-dollar strategy are numerous. The advantages of this were stated in one of Stackoverflow's answers.

  • Simple to use and compatible with every language.
  • Enough precision to handle fractions of a cent.
  • Works for very small per-unit pricing (like ad impressions or API charges).
  • Easy to maintain accuracy through calculations and apply rounding at the final output.

Google are using this approach too (see in the Google Standard Payment doc)

Monetary values in this API are represented using a format called "micros", a standard at Google. Micros are an integer based, fixed precision format. To represent a monetary value in micros, multiply the standard currency value by 1,000,000.

🔗How should it be implemented?

The two main things we do are.

  1. In the application or service level, Use microdollar as a default, set an agreement between services and use it end-to-end. You may store these monetary values as bigint in database.
  2. In User interfaces only, we do convert from the micro-dollar to the decimal dollar format. Only user need to see the actual value.

Yes! In UI, we may easily create a utils/microdollar.js that contains 2 functions.

export const toMicrodollar = (dollar)
    => dollar * 1_000_000;

export const fromMicrodollar = (microdollar)
    => microdollar / 1_000_000;

You can add Math.round() or Math.ceil() as a safety net too.

🔗One caution in Javascript

According to mozilla.org reference, JavaScript itself supports integers up to 9,007,199,254,740,991 which is Number.MAX_SAFE_INTEGER. As a result, you should be aware that the maximum with Javascript and the micro-dollar approach is $9 billion, or roughly $9,007,199,254.

When you calculate this in as well, the outcome shouldn't total more than $9 billions.

The bigint are probably much more than that in other languages. Particularly, Golang's "big" package has an almost limitless 😂

The views and opinions expressed in this article are purely mine and do not necessarily reflect the positions of any companies for which I have worked in the past, present, or future.