Shop calculators that give you the answer you can actually use
Free, no sign-up, works on your phone at the machine. The iPhone app adds sheet nesting, saved projects and PDF export, and works with no signal.
Tap drill size calculatorPick the thread, set the engagement, get the drill that is actually in your index.
Board foot calculatorThickness, width, length and quantity in. Board feet and cost out.
Speeds and feeds calculatorRPM and feed rate, with the chip thinning correction most charts leave out.
Bolt circle calculatorEvery hole's X and Y, ready to type into a DRO.
Bend allowance calculatorFlat pattern length for sheet metal, with the K-factor that fits your press.
Belt length calculatorBelt length, ratio, driven speed and the wrap angle that decides whether it slips.
Gear ratio calculatorSingle stage or compound. Ratio, output speed and torque.
Cut list optimizerHow many lengths you need, and exactly what to cut from each one.
Get Bench Math for iPhone
Why another calculator
Most shop math online is either a wall chart photographed badly, or a generic calculator that does not know what a 64th is. These pages do the specific calculation, show the formula, and say where the number comes from, so you can check it rather than trust it.
Every figure is a starting point. Speeds, feeds and K-factors depend on your tooling, your machine's rigidity and the batch of material in front of you.