Built for the decisions behind the dashboard.
Learn how the free ecommerce calculators work and what they are intended to help you decide.
Seller Tools Lab is a free calculator library for ecommerce sellers, operators, and small product businesses. The goal is simple: make the important numbers visible before a price, ad spend, discount, or inventory decision is made.
What the site does
Each calculator focuses on one decision. You enter your own values, the page calculates locally in your browser, and the result is paired with the formula and practical context.
What the site does not do
The calculators are planning tools, not accounting, tax, legal, or investment advice. Results depend entirely on the inputs. Use your own historical data and consult a qualified professional for decisions that require one.
Privacy by design
The calculators do not require an account and do not upload the values you type. If advertising or analytics services are enabled later, the privacy page explains the relevant third-party processing and choices.
How to contact us
Questions, corrections, and calculator suggestions can be sent to the site contact address.