Estimate how long it takes for an underground aquifer to refill.

Calculate arrow kinetic energy in foot-pounds from arrow weight and velocity.

Estimate the impact energy of an asteroid in megatons of TNT from size, density, and velocity.

Calculate the scale height of a planetary atmosphere from temperature and gravity.

Estimate the minimum latitude at which the aurora is visible for a given Kp index.

Compare the carbon footprint of animal vs plant protein.

Correct beer final gravity from refractometer Brix readings during fermentation.

Calculate bicycle speed in mph from cadence, gear ratio, and wheel circumference.

Calculate energy content of wood or biomass based on moisture.

Calculate a black hole's Schwarzschild radius in meters from its mass in solar masses.

Calculate a startup's monthly burn rate and runway from cash balances.

Calculate annual CO2 savings by sharing your commute.

A logistic curve has three knobs: carrying capacity, midpoint, and steepness.

Estimate a comet's tail length based on its distance from the sun.

Estimate the thermal power generated by a compost pile.

Calculate the ideal C:N ratio for your compost pile.

Calculate recession velocity from cosmological redshift using special relativity.

Calculate a CPU's clock cycle duration in nanoseconds from its GHz speed.

Calculate a vessel's speed over ground from heading, speed, and ocean current.

Calculate the current ratio and working capital from current assets and liabilities.

See how many hectares of forest are lost in real-time.

Calculate the delta-V for an orbit change using the Tsiolkovsky rocket equation.

Calculate density altitude from pressure altitude, temperature, and ISA deviation.

Convert mass and volume into density and per-teaspoon weight.