Field manual for home projects
Get the size right
before you buy.
Generic calculators do arithmetic. These do the judgment: surge loads, climate zones, spacing rules, the stuff pros know and charts skip. Every answer shows its math and lists its sources.
Generator sizing
Pick your loads, get watts with surge math.
PowerGenerator for central AC
By tonnage, with the $300 soft start shortcut.
PowerGenerator for a mini-split
Way smaller than you think. Here's why.
PowerAppliance wattage chart
Running and starting watts, 30+ appliances.
HVACMini-split BTU calculator
Climate, ceilings, insulation, sun. Not just sq ft.
HVACMini-split wattage & cost
Draw by size and monthly running cost.
ConcreteConcrete bag chart
Bags per slab and post hole, waste included.
OutdoorFence post spacing
Spacing and depth by fence type, plus post counts.
OutdoorGravel driveway cost
Tonnage math and honest per square foot ranges.
OutdoorPaver patio cost
The whole bill of materials, not just pavers.
OutdoorDeck boards & screws
Counts with waste, plus joist spacing rules.
HVACAttic R-value chart
Your zone target and how many inches to add.
HVACBTU calculator
Window and room AC sizing done right.
OutdoorFence cost calculator
Per-foot ranges by fence type.
OutdoorMulch calculator
Yards and bags, with the bulk break-even.
How answers are built
Each tool is compiled from manufacturer sizing guides, spec sheets and code references, checked against at least two sources, with the list printed on every page. When a rule of thumb has exceptions, the page says so. Full methodology here.