Free Online Calculators
Finance, math, health, construction, and everyday tools in one searchable catalog.
Favorites
Macrame Cord Calculator — Sample, Cut & Spool Plan
Ohm’s law
Parallel & Series Resistor Calculator — Build Mixed Circuits
Pizza Dough Calculator — Ingredients & Mixed Portions
Pool Alkalinity Calculator
Pool Chlorine Calculator
Pool Heater Calculator
Pool Pump Runtime Calculator — Flow, Hours & Cost
Pool Salt Calculator
Pool Volume Calculator — Measure Gallons and Refill
Priming Sugar Calculator — Batch & Bottle Solution Doses
Prop Slip Calculator — Measured Run Comparison
Calculator descriptions
Macrame Cord Calculator — Sample, Cut & Spool Plan
Plan macrame cord lengths from your own knotted sample. Separate working and filler cords, add cut margin, and see an intact cutting plan for whole spools.
Ohm’s law
Find two unknown electrical quantities from any two measured values. Explore how resistance changes current and power with fixed voltage or current.
Parallel & Series Resistor Calculator — Build Mixed Circuits
Combine resistors in parallel, series or nested groups. Keep every original part and inspect its DC voltage, current and power.
Pizza Dough Calculator — Ingredients & Mixed Portions
Calculate flour, water and other ingredients for dough balls or mixed pizza and pan sizes. Keep the total dough mass and handling loss explicit.
Pool Alkalinity Calculator
Estimate sodium bicarbonate from measured pool alkalinity and your product label. Plan packages and recalculate from a fresh water test.
Pool Chlorine Calculator
Estimate a measured free-chlorine adjustment from your pool volume, test reading, chosen target and the exact strength unit on your product label.
Pool Heater Calculator
Plan pool heat-up time, the heater rating needed for a deadline, and optional gas or heat-pump cost using your measured water volume and cooldown.
Pool Pump Runtime Calculator — Flow, Hours & Cost
Plan daily pool-pump hours, circulated volume and energy from your actual flow and watts, with an optional second setting for a cleaner or other task.
Pool Salt Calculator
Work out how much pool salt to weigh, how many bags to buy and what remains. Preview salt levels and compare high-salt readings.
Pool Volume Calculator — Measure Gallons and Refill
Measure a pool’s inside dimensions, floor zones and waterline to estimate current gallons, full capacity and refill water.
Priming Sugar Calculator — Batch & Bottle Solution Doses
Plan priming sugar for beer or measured sugar-solution doses for mixed bottle sizes. Account for residual CO2, final solution volume and dilution.
Prop Slip Calculator — Measured Run Comparison
Calculate apparent propeller slip from pitch, gear ratio, RPM and measured speed. Keep multiple runs, compare setups and save your measurement record.
