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Straight answers for every home and garden project
Work out how much paint, soil, mulch, tile or seed you need in seconds — then read the reasoning behind the number. Everything here is written by people who have actually done the job.
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Every calculator shows its formula and assumptions, so you can sanity-check the result against your own measurements.
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Home projects
Answers for the house
Paint, tile, flooring, drywall, concrete, insulation and cost — the 25 questions that stop a project before it starts.
Paint Calculator
How much paint do I need for this room?
Get the answerDecoratingWallpaper Calculator
How many rolls of wallpaper do I need?
Get the answerMaterialsFlooring Calculator
How many boxes of flooring should I buy?
Get the answerMaterialsTile and Grout Calculator
How many tiles, and how much adhesive and grout?
Get the answerOutdoor BuildConcrete Calculator
How much concrete do I need?
Get the answerOutdoor BuildDeck and Fence Material Calculator
How much timber does my deck or fence need?
Get the answerGarden projects
Answers for the growing season
Soil volume, mulch depth, spacing, frost dates, watering and light — sized to your beds, your zone, and this month.
What to Plant This Month
What can I plant right now where I live?
Get the answerSoilRaised Bed Soil Calculator
How much soil do I need to fill my raised bed?
Get the answerSoilMulch Calculator
How much mulch do I need for my beds?
Get the answerCarePlant Watering Calculator
How often and how much should I water this plant?
Get the answerLawnLawn Fertilizer Calculator
How much fertilizer does my lawn need?
Get the answerLawnGrass Seed Calculator
How much grass seed do I need?
Get the answerLittle known facts
Things most guides get wrong
Short, sourced notes that overturn common advice — each one explains the mechanism, not just the trivia.
Evening Watering Is Not Always the Safer Choice
Watering at dusk saves water but can cost you the plant: wet leaves overnight are the single biggest invitation to fungal disease.
DecoratingThe Second Coat of Paint Uses Less Than the First
Buying 'two coats worth' at the first-coat rate routinely overshoots — the second coat stretches 10-25% further on most surfaces.
SoilTopsoil, Garden Soil, and Potting Mix Are Not Interchangeable
Filling a raised bed with bagged topsoil is the most common reason a new bed compacts into a brick by its second season.
MulchMulch Piled Against a Trunk Slowly Kills the Tree
Mulch touching a trunk holds bark permanently damp, invites rot and rodents, and encourages roots to circle above the flare.
TilingGrout Joint Width Changes How Many Tiles You Need
Tile quantity is calculated on tile size plus joint, not tile size — a detail that quietly changes the order on any large floor.
ConcreteIt Takes Forty-Five 80 lb Bags to Make One Cubic Yard
One cubic yard of concrete is about forty-five 80 lb bags or sixty 60 lb bags — roughly 1.6 tonnes you carry by hand.
The Knowledge Library
Long-form guides, reference charts, plant and material profiles, a plain-English glossary, and honest project cost ranges — all cross-linked to the tools that use them.