Math & Numbers
Calculate adjusted R squared from R squared, sample size, and predictor count
adjusted-r-squared-calculatorMath & Numbers
Calculate the absolute value of positive, negative, or decimal numbers and explain the sign relationship
absolute-value-calculatorFinance
Generate Bitcoin addresses from private keys for different address types
btc-address-generatorFinance
Validate Bitcoin addresses and detect address type (P2PKH, P2SH, Bech32)
btc-address-validatorCalculator
Calculate probabilities for poker hands and card combinations
card-probabilityDate & Time
Calculate business days excluding weekends
business-day-calculatorMath & Numbers
Convert US liquid gallons to liters with configurable decimal precision
gallon-to-literMath & Numbers
Convert force between newton (N, SI base), kilonewton (kN), dyne (dyn, CGS = 10⁻⁵ N), pound-force (lbf = 4.4482216152605 N), kilogram-force (kgf = 9.80665 N), and poundal (pdl = 0.138254954376 N). All factors derive from the exact defining constants 1 lb = 0.45359237 kg, 1 ft = 0.3048 m, and standard gravity g₀ = 9.80665 m/s². Converts via newton to the target unit and lists the equivalent value in all six units. Reference: 1 kg of mass on Earth ≈ 9.80665 N (1 kgf); an adult weighs ≈ 700 N.
force-unit-converter-extendedMath & Numbers
Convert fuel consumption / fuel economy between L/100km, miles per US gallon (mpg US), miles per Imperial gallon (mpg UK), and km/L. mpg and L/100km are reciprocal (higher mpg = lower L/100km), so conversion goes through the km/L axis, not a single multiplier. Defining constants are exact by law: 1 US gallon = 3.785411784 L (NIST HB 44), 1 Imperial gallon = 4.54609 L (UK W&M Act 1985), 1 mile = 1.609344 km (1959 agreement). Reference: a compact car at ~6 L/100km ≈ 39 mpg US ≈ 47 mpg UK.
fuel-consumption-converterMath & Numbers
Convert volumetric flow rate between m³/h (cubic metres per hour), L/min (litres per minute), gpm (US gallons per minute, 1 gal = 3.785411784 L), and cfm (cubic feet per minute, 1 ft³ = 28.3168466 L). Converts via m³/s to the target unit and also lists the equivalent value in all four units for reference. Used for pumps, HVAC, compressed air, and piping.
flow-rate-volume-converterMath & Numbers
Estimate multi-segment trip fuel, cost, CO2, route-condition weighting, and carpool sharing.
fuel-cost-trip-calculatorMath & Numbers
Calculate the gear module m. m = d/z = p/π. Solve the module from the pitch diameter d and tooth count z, or from the circular pitch p. Also returns the pitch diameter, circular pitch and addendum.
gear-module-calculator