Blog
Guides to the math behind the tools — readability formulas, pricing your work, sizing a build, and planning a game world.
What Etsy actually takes from your sale (and how to price around it)
A full breakdown of Etsy's real fee stack — listing, transaction, payment processing, and ads — and why pricing off "price minus cost" leaves real profit on the table.
KDP royalty tiers explained: why some ebooks earn 70% and others only 35%
How Amazon KDP's price-band eligibility rule, per-megabyte delivery fee, and paperback print-cost floor determine what a self-published book actually earns.
Exclusive vs. non-exclusive ACX distribution: the real royalty math
Why the 40% exclusive royalty rate isn't automatically better than 25% non-exclusive once a narrator royalty-share split enters the picture, with a worked monthly and annual projection.
Why your print-on-demand shop isn't as profitable as it looks
Breaking down base/blank cost, platform fees, payment processing, and ad spend to show why thin per-unit POD margins need volume or ad efficiency to actually work.
The real cost of a handmade candle (it's not just wax)
Walking through wax, fragrance load, pour waste, wick, container, label, packaging, and labor costs with a worked unit-cost example and markup guidance.
Cold-process soap math: superfat, lye, and getting the ratio right
How SAP values, superfat percentage, and water ratio determine the exact lye amount a cold-process soap batch needs, with a worked example and an important lye-safety disclaimer.
Pricing stickers: why bulk orders should cost less per unit
Why a 100-sticker order should never cost 100x a single sticker — the real material and weeding-labor cost stack behind a fair unit price, and how to build a volume discount curve that actually makes sense.
Embroidery pricing: stitch count is the number that matters
Why a small, dense embroidery design can cost more than a large simple one, how the one-time digitizing fee amortizes across a run, and a worked unit-cost example.
How to price art commissions without guessing
Piece type, extra characters, background complexity, and usage license all change what a commission is worth — including the license factor most artists forget to charge for. A full worked example.
Is that craft fair booth actually worth it? Do the math first
A $75 booth fee is the smallest part of what a market day actually costs. How to turn booth fee, travel, rental, and COGS into the two numbers that decide whether to book the table: effective hourly wage and break-even units.
How much resin do you actually need? (mold math explained)
The dimension formula and water-fill method for measuring mold volume, why a waste allowance matters, and how to convert volume into weight and cost — worked examples for a rectangular and a cylinder mold.
Board and batten spacing: the math behind a symmetric accent wall
Why even spacing beats a fixed reveal on a board and batten wall, and the rounding formula — plus the "n+1 gaps" rule — that keeps every batten identical, corner to corner.
Why herringbone tile needs more material than you think
The real reason herringbone (18%) and chevron (20%) tile patterns waste more material than a straight lay (10%), and a worked tiles-boxes-cost example for the same floor in all three patterns.
Planning a deck: boards, gaps, and fasteners that actually add up
Why the 3/16-inch board gap matters, how joist spacing determines your fastener count, and screws vs. hidden clips — with a full worked example for a 20x12 deck.
Wallpaper math: why pattern repeat changes how many rolls you need
How a pattern repeat forces every wallpaper drop to round up to the next full repeat length, cutting usable drops per roll — with a before/after example showing exactly how many more rolls it costs.
Epoxy garage floor coating: how many kits do you actually need?
Why epoxy coverage scales with number of coats and not just floor area, why kits always round up (never split), and when a primer coat is worth the extra cost — with a full worked example.
French drain materials: gravel, pipe, and fabric by the numbers
Why gravel volume must subtract the pipe it surrounds, why landscape fabric matters long-term, and standard depth and slope conventions — with a worked example converting trench dimensions into cubic yards, tons, and cost.
How much soil for a raised garden bed? Bags vs. bulk
Mel's Mix vs. a simple topsoil/compost blend, and the volume threshold where bulk delivery beats bagged soil on cost — with a worked example for multiple beds.
Sizing an LED strip power supply (and avoiding voltage drop)
Why you should never size a PSU to exactly your calculated load, the standard headroom convention, and when a long strip run needs power injection at both ends — with a worked PSU-size lookup.
What it actually costs to charge an EV vs. fill up with gas
Why a "75 kWh battery" costs more than 75 kWh to charge, the real price gap between home and DC fast charging, and a worked road-trip cost comparison against a gas car.