A calculator that scales a soil recipe to every bed

Where it stands

The Bed Amendment Calculator is an in-house tool, built in September 2026 for cultivators who amend their own soil. There is no client and no usage number on this page. It describes what the tool does and how it was built.

The problem

Living-soil recipes are written per cubic foot or per cubic yard. Beds are measured in feet and inches, and one room usually holds several sizes. Every re-amend means the same arithmetic: work out each bed’s volume, scale every ingredient, turn half cups into gallons or pounds, and hope nobody slipped a decimal.

The recipe itself is often handed down or copied from a forum, with no easy way to see whether it is short on calcium or heavy on nitrogen until the plants say so.

What we built

• A library of your mixes. Write a recipe once, per cubic foot, cubic yard, gallon, or liter of soil. Paste it straight from your notes in almost any format, like “1/2 cup kelp meal” or “kelp meal, 0.5, cup”, or upload a CSV or text file.
• Beds, not math. Enter the length, width, depth, and number of each bed, or tap a common size. The tool works out the soil volume and multiplies every ingredient.
• Amounts people can measure. Totals come out in the unit that makes sense for the job: tablespoons for one small bed, gallons or pounds for a full room, or metric if you prefer. Kitchen measures round to the nearest eighth of a cup.
• A mix sheet for the crew. One table with the amount for each bed and the total to mix, ready to copy as text or save as a spreadsheet.
• A balance check. Each ingredient is matched against a library of 30 common amendments and soil ingredients, with typical label analyses. The tool estimates pounds of nitrogen, phosphate, potash, calcium, magnesium, and sulfur per cubic yard, shows each against a target range for a new soil build or a between-cycle re-amend, and explains gaps in plain language, like “No fast calcium source. Try gypsum, crab meal or oyster shell.”
• Slow release counted separately. Rock dust and shell break down over months, so they are shown apart from what is available this cycle instead of inflating the numbers.
• Your numbers win. Any ingredient can take the analysis printed on its own bag and be saved to a personal ingredient list. Target ranges can be set from a soil test.

The honest part

The balance check is an estimate. Label analyses vary by brand and batch, and a cup of kelp meal does not weigh what a cup of basalt does. The tool says so on screen, uses the numbers from your own bag when you enter them, and treats its default ranges as a starting point for a soil test to replace. It is a planning tool, not a lab.

What is next

A second tool is in the works: a planner that lets a cultivator scale a whole grow up or down and see what the change takes before committing to it. It is not built yet. When it is, it will get its own page.

Why it matters for your business

Every trade has a calculation that gets done by hand, every week, by the one person who knows how. Put it in a tool, check the inputs, and show the working, and the whole crew can get it right. The math is simple. Knowing which math the crew actually needs is the part that takes someone who has listened to them.