Get the number right before you cut.
Small calculators for the moment you are stuck mid-job. Each one cites the rule it uses, draws what it means, and is checked against worked examples before it goes live.
Framing & structure
Joist Hole & Notch Checker
Hole and notch limits for sawn-lumber floor and ceiling joists, checked rule by rule and drawn on the joist.
how big of a hole can I drill in a floor joistStud Hole & Notch Checker
Hole diameter, edge distance and notch depth for a wall stud against the 2021 IRC limits, rule by rule.
how big a hole can I drill in a studEgress Window Size Checker
Clear opening area, width, height and sill height of a window against the IRC escape-opening size rules, with the window well.
is my window big enough for egressStair Rise & Run Calculator with Code Check
Risers, exact riser height, treads and total run for a straight stair, each code limit cited, with a mark-out table for the stringer.
how many steps for a 108 inch riseBaluster Spacing & Guard Height Calculator
Evenly spaced balusters on a level run with every gap under the 4 in sphere limit, a mark-out table from the post, and the guard height check.
how many balusters do I need for a 6 ft section
Ducts, pipes & wiring
Dryer Vent Length Checker
Straight duct plus elbows against the 2021 IRC 35 ft limit, with the deduction for every elbow type.
how long can a dryer vent be with 2 elbowsTrap Arm Length Checker
Trap-to-vent distance, slope and fall against the IPC / IRC or UPC table for your trap and pipe size, drawn to check.
how far can a p-trap be from the ventBathroom Fixture Clearance Checker
Toilet, sink and shower clearances against the IRC or UPC minimums, each rule pass or fail, drawn in plan.
how much space do you need around a toilet by codeAttic & Crawl Space Vent Area Calculator
Net free vent area for an attic (1/150, or 1/300 with its conditions) or a crawl space, split high and low and counted in vents.
how many roof vents do I need
Cabinets & furniture
Cabinet Door Cut List
Opening and overlay in; door size and the cut length of every stile, rail and panel out, with a labelled drawing.
how long to cut rails for shaker cabinet doorChair Leg Angle Calculator
Rake and splay to sightline and resultant for staked legs, and back, with the convention drawn on the seat.
what angle to drill chair or stool legs that lean two ways
Tile, trim & finishes
Sewing & quilting
Music
Office & paperwork
Garage
Why these are different
- The source is on the pageEvery tool links the code section, standard or published derivation its numbers come from.
- Tested before it ships391 worked examples across the site must all pass or the site does not publish. How we test.
- A drawing, not just a numberResults come with a diagram you can check against the piece in front of you, and a sheet you can print.
- Nothing to sign up forThe calculators run in your browser. No account, and your numbers are not sent anywhere.