Instant answers, no sign-up
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.
By Jim Vernon · Last updated
Key facts at a glance
- 48 free calculators — 24 for home projects, 24 for the garden. No sign-up, no paywall.
- One gallon of interior paint covers about 350–400 sq ft on a primed, smooth wall — plan two coats over any colour change.
- A 4 ft × 8 ft × 12 in raised bed needs about 32 cu ft (1.2 cu yd) of soil, and settles roughly 10–20% in the first season.
- Mulch goes 2–3 in deep: one cubic yard covers about 108 sq ft at 3 in.
- Every result shows its formula, its assumptions, and the units it uses, so you can check it against your own measurements.
Can I trust these numbers?
Every calculator shows its formula and assumptions, so you can sanity-check the result against your own measurements.
Who writes these guides?
Guides and facts are researched and reviewed by hand, with the reasoning and sources stated in plain language.
Is it really free?
No account, no paywall, no data sold. Supported by advertising that stays clearly separated from the content.
Independent site — no magazine affiliation
Home & Garden Answers is an independent, fan-run website. We are not affiliated with, sponsored by, or endorsed by any magazine, including Home & Garden, Better Homes & Gardens, or any other publication.
Home projects
What can I work out 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
What can I work out for the garden?
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
What do most home and garden 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.
Quick comparison
How much material does one unit actually cover?
The five coverage figures people look up most, side by side. Each row links to the calculator that applies the figure to your own measurements.
| Material | One unit covers | Typical depth / coats | Add for waste | Calculator |
|---|---|---|---|---|
| Interior paint | 350–400 sq ft per gallon | 2 coats over a colour change | 5% | Paint → |
| Bark mulch | 108 sq ft per cubic yard | 3 in deep | 10% | Mulch → |
| Raised-bed soil mix | 27 cu ft per cubic yard | 10–12 in bed depth | 10–20% settling | Raised bed soil → |
| Ready-mix concrete | 0.45 cu ft per 60 lb bag | 4 in slab | 10% | Concrete → |
| Cool-season grass seed | 1,000 sq ft per 3–4 lb (new lawn) | 1/4 in soil cover | 0% (overseed at half rate) | Grass seed → |
Where do these numbers come from?
Coverage rates are cross-checked against manufacturer data sheets and public extension-service and government guidance. Primary references we use most:
- USDA Plant Hardiness Zone Map — zone boundaries used by the frost-date and planting tools.
- ENERGY STAR insulation and air-sealing guidance — recommended R-values behind the insulation calculators.
- US EPA WaterSense — fixture flow rates used in the water-use and irrigation tools.
- USDA NRCS soil texture guidance — soil and amendment assumptions.
- NFPA smoke alarm guidance — placement and replacement intervals in our safety charts.
Full method: editorial standards.
What is in 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.