QKitBoxGuides
Longer answers to the questions behind the tools — pricing math, shipping rules, listing work and document privacy. Every example is computed with the same code the tools run, and every platform claim links to its source.
Why a 50% markup is only a 33% margin, with a conversion table computed from the formula — and how to hit a target margin from cost.
Pairs with: Discount & Markup Calculator · Fee & Profit Calculator
The formula 1 ÷ profit margin, a table for common margins, and a full worked campaign — plus where ROAS alone misleads.
Pairs with: ROAS & Break-even Calculator · Fee & Profit Calculator
Why dividing by 1 + rate beats subtracting a percentage, with worked examples at three rates. Not tax advice — arithmetic.
Pairs with: Sales Tax & VAT Calculator
How carriers price air: the 12×10×8 box that bills at 6.9 lb, USPS's one-cubic-foot exception, and how one inch of box saves money.
Pairs with: Dimensional Weight Calculator
The rules, a complete worked tag set for one product, and the wasted-slot patterns to avoid. Rules as documented by Etsy.
Pairs with: Etsy Tag Builder · Title Length Checker
What browser-side PDF tools can and can't do, how to verify nothing is uploaded, and a rotate → extract → merge workflow.
Pairs with: Merge PDF · Extract Pages · Rotate Pages