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A growing library across many topics. Every calculator shows its formula and cites its sources.

HomeGarden

Lawn Fertilizer Rate Calculator

Find how much fertilizer product to apply per 1,000 sq ft and for your total lawn area, based on the target nitrogen rate and the fertilizer analysis.

HomeGarden

Mulch Coverage Calculator

Calculate the volume and number of bags of mulch needed to cover a garden bed at a given depth.

HomeGarden

Raised Bed Soil Calculator

Find the cubic feet and number of bags of potting mix needed to fill a raised garden bed.

HomeGarden

Plant Spacing Calculator

Calculate how many plants fit in a rectangular bed using standard grid spacing or the Square Foot Gardening density method.

HomeUtilities

Utility Bill Split Calculator

Divide a shared utility bill among people by weight, square footage, or any proportional share.

HomeUtilities

Utility Bill Estimator

Estimate a monthly and annual utility bill from usage quantity, rate, and a fixed charge.

HomeUtilities

Utility Bill Prorate Calculator

Calculate the prorated share of a bill for a partial billing period.

ConstructionLumber

Board Feet Calculator

Convert thickness, width, length, and piece count into board feet using the standard lumber tally.

ConstructionLumber

Linear Feet to Board Feet Converter

Convert a run of linear feet at a nominal thickness and width into board feet.

ConstructionConcrete

Concrete Volume Slab Calculator

Find cubic yards of concrete needed for a rectangular slab from length, width, and thickness.

ConstructionDecks

Deck Board Count Calculator

Estimate the number of deck boards needed for a rectangular deck area at a given board width and gap.

ConstructionDecks

Deck Stair Stringer Calculator

Calculate stair rise, run, stringer length, and step count from total rise and preferred tread depth.

ConstructionRoofing

Roof Pitch to Angle Calculator

Convert a roof pitch expressed as rise-over-run (e.g. 6/12) to the corresponding angle in degrees.

ConstructionMaterials

Gravel Tons by Area and Depth Calculator

Estimate tons of gravel or crushed stone needed for a rectangular area at a given depth and material density.

ConstructionMaterials

French Drain Gravel Calculator

Estimate the washed drainage stone for a french drain trench in cubic yards and tons, subtracting the perforated pipe.

ConstructionMaterials

Topsoil and Fill Dirt Calculator

Estimate topsoil or fill dirt for a rectangular area in cubic yards and tons, with an optional allowance for settling.

ConstructionMaterials

Asphalt Tonnage Calculator

Estimate the tons of hot-mix asphalt for a paving area from length, width, compacted thickness, and mix density.

ConstructionMaterials

Paver Base and Sand Calculator

Estimate crushed-stone base and bedding sand for a paver patio or walkway in cubic yards and tons, with a base compaction allowance.

ConstructionMaterials

Excavation Cut and Fill Calculator

Convert excavation bank volume into loose and compacted volumes with swell and shrink factors, and check the cut and fill balance.

ConstructionFlooring

Flooring Area & Waste Calculator (Boxes)

Turn a room rectangle or known area, a waste percent, and coverage per box into the number of flooring boxes to order.

ConstructionFlooring

Underlayment Roll Count Calculator

Estimate rolls of foam, cork, or felt underlayment from floor area, roll coverage, and an overlap percent.

ConstructionFlooring

Subfloor Plywood / OSB Sheet Calculator

Estimate how many 4x8 plywood or OSB panels you need to sheathe a floor area, with a cut-and-fit waste allowance.

ConstructionPaint

Paint Calculator: Gallons for a Room

Estimate gallons of wall paint from room size, door and window openings, coats, spread rate, and waste.

ConstructionPaint

Primer Calculator: How Much Primer You Need

Estimate gallons of primer for a known area from the coat count, primer spread rate, and a waste allowance.

ConstructionPaint

Trim Paint Calculator: Gallons for Baseboard and Casing

Estimate trim paint from the linear feet of baseboard, casing, and doors, the trim height, coats, and spread rate.

ConstructionPaint

Wood Stain Calculator: Coverage and Gallons

Estimate gallons of deck or fence stain from the area, coats, stain spread rate, and a waste allowance.