DIY project math guides
The reasoning behind the calculators — real coverage rates, where flooring waste actually goes, and when bulk beats bags — written by people who have driven back to the store mid-project so you don't have to.
How Much Mulch to Top Up Each Year: The 1-Inch Refresh Number
How much mulch to top up each year? A 1-inch refresh is about a third of a 3-inch install. Worked bag counts for 200, 400 and 600 sq ft, plus a probe rule.
What It Actually Costs to Mulch Your Yard Yourself: Bags vs Bulk
How much does it cost to mulch your yard, bags vs bulk? Three worked receipts at 400, 800 and 1500 sq ft, plus the square-footage crossover where bulk wins.
DIY Material Cost Break-Even: Bulk vs Bags and Gallon vs Quart Crossover Points
DIY material cost break-even, bulk vs bags: the crossover square footage for mulch, where a gallon beats 3 quarts, and the flooring extra-box math.
How Much Flooring for an L-Shaped Room (Split-Into-Rectangles Method)
How much flooring for an L-shaped room: split it into two rectangles, sum the square feet, add 10–12% waste, and round to boxes — worked end to end.
Flooring Two Connected Rooms as One Continuous Run: How Much to Buy
How much flooring for two rooms in a continuous run: worked sqft for living + hall + bedroom, why racking eats 12% waste, doorway fills, and dye-lot rules.
How Much Paint for a 2-Car Garage Interior? Walls, Ceiling, and Bare Block
How much paint for a 2 car garage interior? A 24x24 garage needs far more than the usual '2-3 gallons' once you add the ceiling and a bare block or drywall.
How Much Paint for a Fence (Both Sides)? Why New Cedar Drinks Twice the Coverage
How much paint for a fence both sides: a 100-ft, 6-ft fence is 1,200 sq ft. Real gallon math for smooth vs. raw cedar, one vs. two coats, brush vs. spray.
How Much Paint for a Vaulted Wall With a Triangle Gable? The Triangle Math
How much paint for a vaulted wall with a triangle gable? Split it into a rectangle plus a triangle — here is the worked 550 sq ft math and the gallons.
How Much Paint for a 1,500 Sq Ft House Exterior? Floor Size Isn't Wall Size
How much paint for a 1500 sq ft house exterior? Floor area isn't wall area. The perimeter-times-height math lands you in the 8–15 gallon range — here's why.
How Much Stain for a Deck With Railings? Counting Every Surface
How much stain for a deck with railings? A 12x16 deck hides ~334 sq ft once you count rails, balusters, posts, and stairs — here is the surface-by-surface math.
How Many Boxes of Laminate for Stairs (or Vinyl Plank)?
How many boxes of laminate for stairs: a 13-tread flight needs ~4 boxes once you add the 30–35% stair waste pros budget — worked step by step, with a table.
How Much Mulch for a Tree Ring? Bags by Ring Width (the Donut Math)
How much mulch for a tree ring: the donut-shaped annulus math, worked bag counts for 3/4/6 ft rings at 3 inches, and why full-circle calculators over-order.
How Much Paint for Kitchen Cabinets? Quarts by Door Count
How much paint for kitchen cabinets? Count doors and drawer fronts, not wall square footage. Worked quart math for galley, L, U, and island layouts.
How Many Bags of Mulch in a Cubic Yard? Bag vs Bulk Math
How many bags of mulch in a cubic yard? 13.5 two-cubic-foot bags — plus the bag-vs-bulk break-even math that decides which one to buy.
Ceiling Paint vs Wall Paint: Why the Math Is Different
Ceiling paint vs wall paint math explained: why length-times-width with no deductions, one coat, and a flat sheen change how many gallons you buy.
Do You Need Primer? How to Count It Separately From Paint
Do you need primer? Five wall conditions that demand it, three that skip it, plus the math for counting primer gallons separately from paint.
Do You Need Underlayment? Roll Math and When to Skip It
Do you need underlayment under laminate or vinyl plank? Quick answers on attached pads, concrete subfloors, and how many 100 sq ft rolls to buy.
How Much Extra Flooring to Buy: Waste % by Pattern
Flooring waste percentages by pattern: 10% straight, 15% diagonal, 20% herringbone — and where the waste actually goes, from end cuts to defect culls.
How Much Gravel for a Patio Base? Depth and Tonnage Math
Gravel for a patio base, worked step by step: cubic yards for a 10x20 at 4 inches, the 20–25% compaction allowance, and yards-to-tons math.
How Many Boxes of Laminate for a 10x12 Room?
How many boxes of laminate flooring a 10x12 room needs: 6–8 boxes depending on coverage per box, with the waste math worked out step by step.
How Much Paint for a 12x12 Room? The Real Two-Coat Math
How much paint for a 12x12 room? Two gallons covers two coats on 8-ft walls — here is the perimeter, opening, and ceiling-height math behind that number.
Leftover Paint: How Much Extra to Buy for Touch-Ups
Touch-up paint math from a year of field notes: how much extra to buy, quart vs gallon prices, and storage that keeps leftovers usable.
LVP vs Laminate vs Engineered Hardwood: Cost per Sq Ft
LVP vs laminate vs engineered hardwood cost compared on a real 600 sq ft project — material, underlayment, waste, and transitions priced out.
Mulch Depth Guide: What 2, 3 and 4 Inches Really Cover
Mulch depth math made simple: how far a 2 cu ft bag goes at 2, 3 and 4 inches, which depth fits each job, and the two mistakes that waste bags.
How Many Square Feet Does a Gallon of Paint Cover?
Paint coverage per gallon runs 250–400 sq ft depending on surface. Realistic numbers for smooth walls, texture, bare drywall, brick, and ceilings.
Painting Over Dark Walls: How Many Coats It Really Takes
Painting over dark walls takes more paint than the can promises. Real coat counts and gallon math for covering navy, black, and red walls.
How Much Soil for a 4x8 Raised Bed (and the Cheapest Mix)
How much soil a 4x8 raised bed needs at 6, 10, and 12 inches — exact bag counts, bulk yard math, and a layered fill that cut my cost in half.
Calculating Tile for a Small Bathroom, Fixture by Fixture
Tile math for a small bathroom, worked fixture by fixture: what to subtract for the tub and vanity, flange cuts, and why 5x8 rooms need extra waste.
Topsoil vs Compost vs Garden Soil: How Much of Each
Topsoil, compost, and garden soil compared: what each bag is for, common blend ratios, and the cubic-foot math for a mixed soil order.