About HammerCalc

Every DIY project starts with the same two questions: how much material do I need, and what will it cost? Get the first one wrong and you either pay for a second delivery or watch half a pallet of concrete bags harden in the garage. HammerCalc exists to get that answer right before you order.

How the calculators work

Each calculator applies the standard estimating formula used in the trades: geometry first, then a stated waste or compaction factor, then a conversion into the package sizes US stores actually sell (80 lb bags, bundles, boxes, sheets, cubic yards). The formula and its assumptions are printed on every page, so you can check our math with a pencil. We'd rather you verify than trust blindly.

What we don't do

We don't hide assumptions, and we don't pretend an online estimate replaces a site visit. Slopes, odd corners, settling soil, and product differences all change real quantities. The calculators tell you when to round up, when bulk delivery beats bags, and when a job needs a licensed professional, especially anything structural.

Who we are

HammerCalc is built by the same small team behind NetPayMap: engineers who like calculators with their work shown. Spot a formula that doesn't match how your trade does it? Tell us. Corrections get fixed first.