🛠️ 4 Hobby Calculators
Real numbers for your hobby — what a 3D print actually costs, how many gallons your tank really holds, how much substrate to buy, and how long to cut a dipole.
3D Printing, Aquarium & Radio Calculators
Each tool is interactive: price a print with material, electricity, depreciation and failure overhead; convert any tank shape to gallons and liters; plan gravel, sand or aqua soil by the bag; and get dipole cut lengths for any frequency.
3D Printing Cost Calculator
Free 3D printing cost calculator: filament, electricity (18.83¢/kWh US avg), depreciation and failure rate. A 150 g PLA ...
Fish Tank Volume Calculator
Free fish tank volume calculator for 6 shapes. US gallons (231 cu in each), liters, UK gallons, water weight at 8.34 lb/...
Aquarium Substrate Calculator
Free aquarium substrate calculator: pounds, kg, liters, and bag counts from tank footprint and depth. A 20-long needs ~2...
Dipole Antenna Calculator
Free dipole antenna calculator: 468 ÷ f MHz gives half-wave length — a 40 m dipole cuts to 65 ft 5 in. Presets for 160 m...
Why Run the Numbers First
Hobby math has real stakes: a mispriced print eats your margin, an overstocked tank stresses fish, too much gravel is money in a bucket, and a dipole cut short means starting over with new wire. These calculators use the exact constants that matter — 231 cubic inches per US gallon, 8.34 pounds per gallon of water, 468 ÷ MHz for a half-wave dipole — so you buy and cut right the first time.