Power.
4 instrumentsBatteries, solar, and the electrical math behind everything off-grid.
Battery
Runtime
How long a battery will actually power your load, with Peukert correction for lead-acid.
Open instrument →Amp Hours
Needed
Size a battery bank from your loads, runtime, and days of autonomy.
Open instrument →Amp-Hour
Conversions
Convert between watts, amps, capacity, and runtime in one place.
Open instrument →Solar Panel
Sizing
Size an array from daily energy, sun hours, and battery storage - off-grid, RV, or backup.
Open instrument →Finance.
4 instrumentsPaychecks, rent, taxes, tips, and the math behind qualifying for things.
Take-Home
Pay
Net paycheck after federal, state, FICA, and pre-tax deductions. 2026 brackets.
Open instrument →Tip
Calculator
Tip math and bill splitting for any party size, with round-up and pre-tax options.
Open instrument →NYC 40×
Rent Rule
Does your income clear the 40-times threshold landlords look for?
Open instrument →Arizona
Sales Tax
Retail TPT math with state, county, and city rates baked in.
Open instrument →Body.
4 instrumentsHealth, sleep, due dates, and what's still in your system.
Pregnancy
Due Date
Estimated delivery date from LMP, conception, ultrasound, or reverse - with milestones.
Open instrument →Sleep
Cycle
Best wake times and bedtimes based on 90-minute sleep cycles.
Open instrument →Blood Alcohol
Estimator
BAC from drinks, weight, sex, and time, with time-to-sober projection.
Open instrument →Caffeine
Half-Life
How much caffeine is still in your system, hour by hour, after every cup.
Open instrument →Build.
3 instrumentsConstruction, repair, and the geometry of getting things straight.
Concrete
Volume
Cubic yards needed for slabs, columns, and post holes - plus bags, trucks, and cost.
Open instrument →Stair
Stringer
Risers, treads, total run, stringer length, and IRC code check for any rise.
Open instrument →Gutter
Slope
Total drop and end heights for a properly pitched gutter run.
Open instrument →Farm.
4 instrumentsLivestock, agriculture, and the schedules around growing things.
Chicken
Hatching
21-day incubation timeline for chicken eggs. Candling, lockdown, and hatch milestones.
Open instrument →Guinea Fowl
Hatching
28-day incubation timeline for guinea fowl eggs. Tailored to the species' thick shells and humidity needs.
Open instrument →Turkey
Hatching
28-day incubation timeline for turkey eggs. Same schedule for wild, heritage, and Broad Breasted.
Open instrument →Hog
Gestation
Farrowing date from breeding date - or run it the other way around.
Open instrument →Shop.
1 instrumentTools, fluids, two-stroke math, and the workshop arithmetic that keeps engines alive.
Speed.
2 instrumentsVehicles, fuel cost, and the power-to-weight math of going fast.
Sport.
2 instrumentsRunning pace, jumps, reach, and what it takes to clear a target.