How we calculate

Every calculator on this site follows the same rules, so you know what a result means no matter which page you’re on.

Units

We calculate in US units: feet, square feet, cubic feet and yards, gallons, and pounds. When you switch to metric, we convert what you type and what you see using exact factors (1 foot = 0.3048 meters, 1 US gallon = 3.785 liters). Store package sizes stay in US units, since that’s how they’re sold, and we show the metric equivalent next to them.

Rounding

We never round down what you need to buy. Areas and volumes are kept unrounded until the last step. Then the amount is rounded up to whole packages: cans, boxes, bags, sheets, or boards. When two package mixes cost almost the same (within 3%), we suggest the one with fewer containers.

Waste and extra

Real projects use more than the bare measurement. Paint stays in rollers and trays, tile and flooring get cut, and loose materials settle. Each calculator starts with a waste allowance taken from manufacturer or trade guidance and explains it on the page. You can always change it.

Coverage and yields

Where a manufacturer publishes a range, such as 350 to 400 square feet per gallon, we use the cautious end or a middle value and say which. When a number is our own estimate rather than a published figure, the page says so.

Prices

Cost estimates use example prices that you can edit. They’re there to show how package sizes compare, not to quote what your store charges. Prices vary by region, brand, and season.

Sources by calculator

This list updates automatically as we add calculators.

Concrete Calculator

• Concrete Mix (No. 1101), product data sheet, Quikrete. Yield per bag: 0.30 cu ft (40 lb), 0.375 (50 lb), 0.45 (60 lb), 0.60 (80 lb), 0.675 (90 lb). Minimum 2 in thick, control joints every 6 to 8 ft, curing times.
• CIP 8, Discrepancies in Yield, National Ready Mixed Concrete Association. Order 4 to 10 percent more than the calculated volume; a 1/8 in error on a 4 in slab is a 3 percent shortage.
• Fast-Setting Concrete Mix (No. 1004), product data sheet, Quikrete. Two 50 lb bags set a 3 in post in a 9 in hole 30 in deep.
• 811 Before You Dig, Common Ground Alliance. Free national service; contact 811 a few business days before digging.

Flooring Calculator

• Pergo Extreme Installation Instructions, Uniclic, Pergo (Mohawk Industries). Add 10% for standard installations and 15% for diagonal ones; install cabinets first; blend planks from several cartons.
• Solid Wood Flooring 3/4 in Strip and Plank Installation Instructions, Bruce. Add 5% for cutting and grading, 10% for diagonal installations, 10% to 15% for glue-down.
• Engineered Hardwood Flooring Installation Guidelines, Herringbone, Shaw Floors. A 5% cutting allowance, with a higher percentage for diagonal, herringbone, or bordered installations.

Mulch Calculator

• Mulch (HGIC 1604), Clemson Cooperative Extension, Home & Garden Information Center. One cubic yard covers 324 sq ft at 1 in; fine mulch no more than 2 to 3 in, coarse up to 4 in, leaves and clippings 2 in; keep mulch 2 to 3 in from woody stems and 6 to 12 in from walls.
• How to Mulch Trees and Shrubs, The Morton Arboretum. 3 to 4 in under trees and shrubs, a couple of inches in perennial beds; check the depth every year and replenish as needed.
• Scotts Nature Scapes Color Enhanced Mulch, ScottsMiracle-Gro. A typical bagged mulch sold in 1.5 and 2 cu ft bags.

Paint Calculator

• Regal Select Interior Paint & Primer, Matte (N548), technical data sheet, Benjamin Moore. Spread rate of 400 to 450 sq ft per gallon; two coats recommended on bare surfaces.
• How Much Paint Do I Need?, This Old House (updated June 2026). 350 to 400 sq ft per gallon for paint, 200 to 300 for primer; porous surfaces need more.

Planting Zone

• USDA Plant Hardiness Zone Map 2023, ZIP code data (phzm_us_zipcode_2023.csv and the Alaska, Hawaii, and Puerto Rico files), PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 5, 2026. Half zone and temperature range for 40,502 ZIP codes, plus the matching 2012 files. Free to redistribute; not the official USDA map.
• USDA Plant Hardiness Zone Map, USDA Agricultural Research Service. The official interactive map.
• USDA Unveils Updated Plant Hardiness Zone Map, USDA Agricultural Research Service, November 2023. 1991–2020 data, 13,412 stations against 7,983 in 2012, 10-degree zones and 5-degree half zones, and why zone shifts are not a direct climate change measure.
• U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), NOAA National Centers for Environmental Information (Palecki and others, 2021), doi:10.25921/4ek7-fk11, accessed October 5, 2026. Frost dates shown in the result.
• 2025 Gazetteer Files, ZIP Code Tabulation Areas, U.S. Census Bureau. ZIP code center points used to find the nearest weather station.
• GeoNames postal codes, United States, GeoNames, licensed under CC BY 4.0 (creativecommons.org/licenses/by/4.0). Place names, and locations for ZIP codes that have no Census area, such as PO box ZIP codes.

Drywall Calculator

• Sheetrock Brand All Purpose Joint Compound, submittal sheet (J1969), USG. Coverage of about 10 gal per 1,000 sq ft of panels; sold in 4.5 gal pails and 3.5 gal cartons.
• Sheetrock Brand Paper Joint Tape, submittal sheet (J1736), USG. About 370 ft of tape per 1,000 sq ft of panels; 250 ft and 500 ft rolls.
• Sheetrock Brand UltraLight Panels, submittal sheet (WB2501), USG. Screws spaced at most 12 in on ceilings and 16 in on walls; 1.25 lb per sq ft; ceilings with framing up to 24 in apart.
• Drywall Calculator, CertainTeed. Advises not subtracting doors, windows, or outlets, and gives quantities without a waste allowance.

Fence Calculator

• Fast-Setting Concrete Mix (No. 1004), product data sheet, Quikrete. Hole about 3 times the post width, depth one third of the post length, top 3 to 4 in filled with soil, 0.375 cu ft per 50 lb bag, two bags for a 3 in post in a 9 × 30 in hole.
• Concrete Mix (No. 1101), product data sheet, Quikrete. Yield of 0.45 cu ft per 60 lb bag and 0.60 per 80 lb bag; slope the top away from the post.
• Suggestions for Installation of Your Western Red Cedar Fence, Alta Forest Products. Three rails, 1/8 in between privacy boards (citing ASTM F537), 4 in between back boards for board-on-board with 6 in boards, no ground contact.
• 811 Before You Dig, Common Ground Alliance. Free national service; contact 811 a few business days before digging.

Frost Dates

• U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), frost and freeze probabilities, NOAA National Centers for Environmental Information (Palecki and others, 2021), doi:10.25921/4ek7-fk11, accessed October 5, 2026. Last spring and first fall dates at 36, 32, and 28 °F with 10, 50, and 90 percent probability, and growing season length.
• Readme for the by-variable and by-station normals files, NOAA National Centers for Environmental Information. Field names, measurement flags (V for year-round frost risk, Y for too few values), and completeness flags S, R, P, and E.
• Frost/Freeze information, National Weather Service, Raleigh, North Carolina. Frost advisory at 33 to 36 °F, freeze warning at 32 °F or below, hard freeze at 28 °F or below.
• 2025 Gazetteer Files, ZIP Code Tabulation Areas, U.S. Census Bureau. ZIP code center points.
• GeoNames postal codes, United States, GeoNames, licensed under CC BY 4.0 (creativecommons.org/licenses/by/4.0). Place names, and locations for PO box and other ZIP codes without a Census area.
• USGS 3D Elevation Program, 1/3 arc-second, served by Open Topo Data, U.S. Geological Survey; Open Topo Data. Elevation at each ZIP code center, used for the height difference to each station.

Gravel Calculator

• Gravel Road Maintenance Manual: A Guide for Landowners on Camp and Other Gravel Roads, Maine Department of Environmental Protection (April 2016). Multiply by 1.11 for compaction; a compacted cubic yard of gravel weighs about 1.6 tons; at least 6 in of base and 4 to 6 in of surface gravel over fabric; crushed rather than rounded gravel; 1/2 in of crown per foot.
• Strength Characterization of Open-Graded Aggregates for Structural Backfills (FHWA-HRT-15-034), Table 7, Federal Highway Administration (June 2015). No. 57 aggregate weighed 95.4 lb per cu ft loose and 108.7 lb per cu ft at maximum density (1.29 to 1.47 tons per cu yd).
• GraniteCrete Math Sheet (revised July 29, 2024), GraniteCrete. 1 cubic yard of decomposed granite equals 1.5 tons.
• Quikrete 0.5 Cu. Ft. 50 Lb. All-Purpose Gravel, Do it Best (retail listing). A 50 lb bag holds 0.5 cu ft, which works out to 1.35 tons per cubic yard for small gravel.

Tile Calculator

• How a Little Extra Can Go a Long Way, Fireclay Tile. Order 15% extra for field tile, and 20% for herringbone, parquet, or specialty shapes.
• VersaBond Professional Thin-Set Mortar, data sheet (TDS-119), CUSTOM Building Products. 85 to 95 sq ft per 50 lb bag with a 1/4 × 1/4 in notch, 60 to 67 with 1/4 × 3/8 in; 24 hours before grouting.
• VersaBond-LFT Professional Large Format Tile Mortar, data sheet (TDS-132), CUSTOM Building Products. 42 to 47 sq ft per 50 lb bag with a 1/2 in square notch or a 3/4 in U-notch at 30 degrees; at least 80% mortar coverage, 95% in wet areas.
• Polyblend Plus Sanded Grout, data sheet (TDS-360), CUSTOM Building Products. Coverage chart by tile size and joint width that our grout formula is checked against; joints from 1/8 to 1/2 in.

Deck Board Calculator

• 2022 Decking Installation Guide, Trex. Gaps of 3/16 in between boards and 1/8 to 3/16 in at ends, two screws per joist, boards span at least three joists, 16 in joists for 1 in boards and 4 in less at 45°, trim 3/16 in off each factory end.
• How to Space and Install Deck Joists, Trex. Joists no more than 16 in on center for standard decking and 12 in for diagonal decking.
• Trex Hideaway Universal Hidden Fasteners (90 pack), Trex. A box of 90 clips covers 50 sq ft with joists 16 in on center.
• DCA 6, Prescriptive Residential Wood Deck Construction Guide (2015 IRC), American Wood Council. Two 8d threaded nails or two #8 screws per joist, about 1/8 in between wood boards, each board on at least three joists, decking from square to 45° to the joists.

Planting Calendar

• GardenNotes #720, Vegetable Planting Guide (reviewed September 2024), Colorado State University Extension. Four frost groups and their spring timing, typical days to harvest, transplant age, and germination soil temperatures.
• Suggested Vegetable Planting Dates for Utah, Utah State University Extension. Frost groups A to D by crop.
• HO-186-W, Indiana Vegetable Planting Calendar (December 2020), Purdue University Extension. Frost groups for collards, kale, mustard, okra, and sweet potatoes, and the list of fall crops.
• FS787, Starting Vegetable Seeds Indoors, Rutgers New Jersey Agricultural Experiment Station. Weeks from seeding to transplant and hardening off.
• HGIC 1267, How Much to Grow: Planning for Year-Round Garden Productivity (March 2026), Clemson Cooperative Extension Home and Garden Information Center. Days to maturity and approximate length of harvest.
• Fall Planting of Vegetables, Iowa State University Extension and Outreach. Fall crop list and days to maturity for cauliflower.
• Fall Vegetable Gardening, 426-334 (SPES-801P), revised March 2026, Virginia Cooperative Extension. Count-back formula with the fall factor and the frost-tender factor, and presprouting seeds.
• U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020), NOAA National Centers for Environmental Information (Palecki and others, 2021), doi:10.25921/4ek7-fk11, accessed October 5, 2026. Last spring and first fall 32 °F dates for the nearest station.
• 2025 Gazetteer Files, ZIP Code Tabulation Areas, U.S. Census Bureau. ZIP code center points.
• GeoNames postal codes, United States, GeoNames, licensed under CC BY 4.0 (creativecommons.org/licenses/by/4.0). Place names, and locations for ZIP codes without a Census area.

Topsoil Calculator

• Sodding: Steps to an Instant Lawn (FS104), Rutgers New Jersey Agricultural Experiment Station. Over very poor soil, at least a 4 in layer of high quality topsoil; incorporate added materials to at least 6 in; lightly roll before laying sod.
• Preparing Lawn Soil and Site, University of Illinois Extension. Aim for 6 in or more of well prepared soil; test the soil while planning; grade 1 to 2% away from buildings; sand is not suggested for improving clay lawns.
• Topdressing a Home Lawn, Clemson Cooperative Extension, Home & Garden Information Center. No more than 1/2 in of topdressing at a time, during the active growing season.
• Scotts Premium Topsoil, ScottsMiracle-Gro. A 0.75 cu ft bag covers 4 sq ft at 2 in, about 0.67 cu ft in place; the product adds peat moss and organic matter to existing soil.

Wallpaper Calculator

• Magnolia Home Gwendolyn Wallpaper, product page, York Wallcoverings. Double roll 20.5 in wide and 33 ft long, about 56.4 sq ft; 20.5 in repeat, drop match.
• Fretwork Wallpaper, product page, Cole & Son. European roll 0.52 m wide and 10 m long; 52 cm straight-match repeat.
• How to Measure for Wallpaper, Graham & Brown. Leave doors and windows in the measurement; allow 10% for waste.
• Wallpaper Frequently Asked Questions, Graham & Brown. Cut each strip 4 in longer than the wall; offset (drop) matches need more paper; buy rolls from one batch.

Raised Bed Soil Calculator

• Soil to Fill Raised Beds, University of Maryland Extension (updated November 6, 2024). Compost and topsoil 1:2 or 1:1, or compost and soilless mix 1:1; on hard surfaces at least 8 in for greens and 12 to 24 in for tomatoes; topsoil up to 20% in beds 16 in or deeper; buying topsoil and testing for lead.
• Building Raised Beds for Vegetable Gardening, University of Maryland Extension (updated November 7, 2023). Raised beds are usually 2 to 4 ft wide and 2 to 12 in high.
• Miracle-Gro Organic Raised Bed Soil, ScottsMiracle-Gro. Product size 1.5 cu ft, the bag size we use for bagged raised bed soil.

Corrections

If you find a mistake, tell us. We fix calculation errors first and update the “last updated” date on the page when we do.

Last updated October 5, 2026.