Battery Runtime Calculator
Estimate battery runtime from Ah or Wh, voltage, load, efficiency, depth of discharge and health, with optional Peukert correction.
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Free calculators for grades, everyday decisions, engineering units and electronics. Open a tool for its formula, examples and assumptions.
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Dress Length by Height Calculator
Estimate shoulder-to-hem length for a chosen floor clearance.
Open toolDrill Tip Length Calculator
Estimate conical drill point length and the tip depth for a full-diameter hole.
Open toolEffective Labor Rate Calculator
Calculate revenue per billed hour or reverse-solve a target.
Open toolGutter Slope Calculator
Find the vertical drop, run, or pitch toward the downspout.
Open toolHaircut Tip Calculator
Calculate a haircut or salon tip, include tax and deposits, compare a fixed or percentage tip and split the amount across staff.
Open toolHours to Decimal Calculator
Convert hours and minutes to decimal hours, or convert back to a duration.
Open toolLabor Percentage Calculator
Find labor cost as a percentage of sales or calculate a target budget.
Open toolm³/h to CFM Converter
Convert m³/h to CFM or back, process a list and compare L/s and L/min. Uses the international foot definition.
Open toolm³/h to GPM Converter
Convert m³/h to US or Imperial GPM in either direction. Keep gallon standards explicit and export bulk conversions.
Open toolMetres per Minute to SFM Converter
Convert machining surface speed in either direction.
Open toolMHz to ns Converter
Convert MHz to a single-cycle period in nanoseconds or ns back to MHz. Calculate the elapsed time for multiple cycles and export a list.
Open toolNecktie Length Calculator
Estimate a necktie shopping length range from height, neck size and knot style. Compare centimetres and inches, then check the tied fit.
Open toolPrice per Pound to Price per Kilogram Converter
Convert a unit price or compare two offers in the same currency.
Open toolRPM to FPM Calculator
Convert RPM to feet per minute using wheel diameter, or reverse FPM to RPM. See metric surface speed and a comparison table.
Open toolShelf Spacing Calculator
Calculate even clear gaps and mark the bottom edge of each shelf.
Open toolSki Boot Size Calculator
Estimate Mondopoint from the longer foot.
Open toolSquare Root Curve Calculator
Curve one score or a class list with a square root or adjustable power curve. Compare averages, find target scores and export results.
Open toolTattoo Tip Calculator
Calculate a tattoo tip from the full service price, account for a credited deposit and tax, round the tip and split payment evenly.
Open toolWords Correct per Minute Calculator
Calculate words correct per minute, raw WPM and reading accuracy from attempted words, errors and seconds. Includes a stopwatch.
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