Home project and energy cost guides
20 guides that turn measurements and official data into numbers you can use: what electricity costs in your state, what an appliance costs to run, and how much paint, flooring or mulch to buy.
Home energy costs
Electricity prices and average bills for every state from the U.S. Energy Information Administration, plus the cost to run appliances and charge an EV at home.
Average Electric Bill by State (EIA Data)
The average U.S. residential electric bill was $142.26 a month in 2024 (EIA). See every state's bill, kWh use and price per kWh, plus how to check your own.
Cost to Charge an EV at Home, by State
Home EV charging cost per 100 and 1,000 miles for all 50 states and DC, using EIA July 2026 residential rates, EPA kWh per 100 miles and gasoline prices.
How Much Does It Cost to Run an Appliance? Watts × Hours × Rate
Estimate what an appliance costs to run: watts × hours ÷ 1,000 × rate, using DOE wattages and EIA July 2026 prices for the U.S., Louisiana and Hawaii.
Residential Electricity Rates by State (Latest EIA Month)
Residential electricity rates for every state and DC in July 2026 from EIA, compared with July 2025. U.S. average: 18.31 cents per kWh, up 4.9% in a year.
Paint, primer and surfaces
Manufacturer spread rates, primer and coat counts, and worked quantities for rooms, cabinets, exteriors, fences and decks.
How Many Square Feet Does a Gallon of Paint Cover? Manufacturer Spread Rates Compared
Manufacturer data sheets list 350–450 sq ft per gallon for interior wall paint and 250–450 for exterior. See 9 products, why film thickness sets coverage, primer and coats.
How Much Exterior Paint for a House: Measure Walls and Gables, Not Floor Area
Floor area can't size an exterior paint job. Measure each elevation and gable, check what your siding is (Census data on new homes), and turn net wall area into gallons.
How Much Paint for a 10x10 Room
Turn a 10-by-10 room's perimeter and wall height into net paintable area, subtract measured openings, and size paint by coats and product coverage.
How Much Paint for a 12x12 Room?
Calculate paint for a 12-by-12 room from measured height and openings, selected-product coverage, and an explicit tested coat plan.
How Much Paint for a 2-Car Garage Interior
Measure garage walls, ceiling, and openings, then calculate each drywall or masonry coating from its selected product coverage and coats.
How Much Paint for a Bathroom
Measure a bathroom's real painted wall area around the tub, vanity, tile and mirror, then size a moisture-friendly paint by coats and coverage.
How Much Paint for a Stairwell
Measure a stairwell's tall, angled walls as rectangles and triangles, then size paint by coats and coverage — the access, not the math, is the hard part.
How Much Paint for an Accent Wall
Size paint for a single accent wall from its measured area, product coverage and tested coat plan, then round to available package sizes.
How Much Paint for Interior Doors and Trim
Estimate paint for doors and trim from door faces and linear feet of casing and baseboard — a small quantity that hides in a different measurement.
How Much Paint or Stain for a Fence (Both Sides) or a Deck With Railings
Measure the actual coated faces of panels, pickets, rails, posts, gates, and edges, then use the selected coating's published coverage.
Kitchen Cabinet Paint Calculator: Doors, Drawers, and Frames
Calculate kitchen cabinet paint and primer from measured doors, drawer fronts, frames, panels, coat counts, and the selected products' coverage rates.
Flooring, boxes and overage
Square footage, overage and carton rounding, L-shaped rooms, stairs, bathroom tile and underlayment.
Flooring Two Rooms Continuously: Area and Transition Checks
Sum connected floor areas, verify the selected product permits the continuous run, enter a cut-plan overage, and round once by carton coverage.
How Much Flooring to Buy: Boxes, Waste Percentage, L-Shaped Rooms, Stairs and Tile
Turn measured area into whole cartons: choose an overage you can justify, see how box rounding changes the count, split L-shaped rooms, and handle stairs and bathroom tile.
LVP vs Laminate vs Engineered Hardwood: Quote Worksheet and Underlayment Check
Compare flooring systems with actual box, accessory, preparation, delivery, and labor quotes instead of unsupported national price ranges.
Mulch, soil and outdoor projects
University extension guidance on mulch depth and raised-bed soil, bags per yard, tree rings and patio-base gravel.
How Much Mulch Do I Need? Depth, Bags per Yard, Tree Rings and Bags vs Bulk
University guidance on mulch depth (1–4 inches, kept off trunks), bag coverage by depth, 13.5 two-cubic-foot bags per yard, tree-ring math, top-ups and the bag-vs-bulk break-even.
How Much Soil for a Raised Bed: Depth by Crop, Mix and Bags (Plus Gravel for a Patio Base)
A 4x8 raised bed takes 21 cu ft of soil at 8 inches and 32 at 12. See extension guidance on depth by crop and compost share, bag counts, and the gravel-base volume-to-tons steps.
Sources are linked on each page. Read how we research, cite and correct our guides.