Hobby and Craft

  • Pixels to Print Size Calculator
    Convert image pixel dimensions to print size in inches and centimeters at a chosen DPI/PPI. Find the largest quality print your photo can make.
  • Projector Throw Distance Calculator
    Calculate how far to place your projector from the screen using its throw ratio and screen width. Get distance in inches, feet, and meters instantly.
  • Hyperfocal Distance Calculator
    Calculate the hyperfocal distance from focal length, aperture, and circle of confusion to maximize depth of field and keep landscapes sharp.
  • Magnification of a Lens Calculator
    Calculate the magnification of a lens from object and image distances using m = -di/do. Find image size, orientation (upright/inverted), and magnitude instantly.
  • Focal Length Calculator
    Calculate the lens focal length in mm from your camera sensor dimension and desired field of view (angle of view) using simple optics geometry.
  • Crop Factor Calculator
    Calculate your camera's crop factor and 35mm-equivalent focal length from sensor dimensions and lens focal length. Free, instant, and accurate.
  • Drone Flight Time Calculator
    Estimate drone flight time from battery capacity, voltage, average power draw and discharge efficiency. Free runtime calculator with worked example.
  • Music Transposition Calculator
    Transpose any musical note up or down by a number of semitones. Get the new note name, pitch-class index (0–11) and octave shift instantly.
  • Note Frequency Calculator
    Convert any piano key number to its frequency in Hz using equal temperament. Set a custom A4 reference pitch and see wavelength and period too.
  • Semitone Calculator
    Calculate the musical interval in semitones (and cents) between two frequencies using semitones = 12 × log2(f2/f1). Fast, accurate, free.
  • Fret Position Calculator
    Calculate exact guitar fret positions from any scale length. Find the distance from nut, bridge, and spacing to the next fret using the 12-tone equal temperament rule.
  • Music Interval Calculator
    Calculate the frequency ratio, cents, and target pitch for any musical interval in semitones using 12-tone equal temperament. Free online tool.
  • Guitar String Tension Calculator
    Calculate guitar string tension in pounds from unit weight, scale length, and target pitch frequency. Perfect for custom string gauge setups.
  • Mulch Calculator
    Calculate exactly how much mulch you need — in cubic feet, cubic yards, or cubic meters — plus weight, bags required, and total cost. Supports rectangle, circle, triangle, or pre-computed total area, with bulk or bag pricing.
  • Fish Weight Calculator
    Estimate a fish's weight from its length and girth, or from length alone using a species shape factor. Get results in pounds, ounces and kilograms.
  • Planter Soil Volume Calculator
    Calculate how much soil fills a tapered rectangular planter or window box. Enter top, bottom and height to get volume in liters, cm³ and m³.
  • Flower Pot Soil Volume Calculator
    Calculate the soil volume of a tapered flower pot from its top diameter, bottom diameter, and height. Conical frustum geometry, results in cm3 and liters.
  • Pool Table Room Size Calculator
    Find the minimum room size for your pool table. Enter playing area and cue length to get the clearance space needed on every side for comfortable shots.
  • Knitting Gauge Stitch & Row Count Calculator
    Convert your knitting gauge (stitches and rows per 10 cm swatch) into the exact number of stitches to cast on and rows to knit for any finished width and height.
  • Circle Skirt Calculator
    Enter your waist circumference and desired skirt length, choose full, 3/4, half, or quarter style, and get the cut measurements for your pattern.
  • Cake Serving Calculator
    Estimate how many slices a round cake serves from its diameter and slice size. Free cake serving calculator for parties, weddings and events.
  • Bulb Spacing Calculator
    Calculate how many flower bulbs you need from bed area and spacing. Supports square and triangular (staggered) planting layouts with instant counts.
  • Speeds and Feeds Calculator
    Free speeds and feeds calculator for CNC milling and machining. Enter SFM, tool diameter, chip load and flutes to find spindle RPM and feed rate (IPM).
  • Board Foot Calculator
    Calculate board feet of lumber from thickness, width, and length in inches. Get total board footage and cost for any number of boards instantly.

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