Free Online Calculators

Finance, math, health, construction, and everyday tools in one searchable catalog.

86 calculators

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Debt Payoff Calculator

Compare debt avalanche and snowball with the same budget. See what to pay each creditor each month, add one-time extras and download your plan.

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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.

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Plant Spacing Calculator — Bed Layout & Plant Count

Plan actual planting places in a rectangular bed, compare row directions and turn the layout into a whole-pack plant order.

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Fence Picket Calculator — Boards, Gaps & Layout

Plan individual fence pickets across unequal bays. See even gaps, inspect board positions, add whole spare boards and print your layout.

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Candle Wax Calculator

Plan mixed candle sizes, weigh wax and fragrance, and work out complete batches from your ingredient stock.

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Yarn Calculator

Estimate blanket yarn from a weighed swatch, preview repeating stripes, subtract partial balls and print a colour-by-colour shopping list.

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Alcohol Dilution Calculator — Water or Alcohol to Add

Calculate water or stronger alcohol to add, prepare an exact final volume, lower or raise ABV, blend two strengths, and convert U.S. proof.

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Square Feet Calculator — Rooms & Floor Plans

Calculate square feet for one room or a full floor plan in exact feet and inches. Add rooms by floor, subtract excluded areas, and estimate materials and cost.

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Tuckpointing Calculator — Mortar, Bags, Labor & Cost

Estimate tuckpointing and repointing from wall area or measured mortar-joint length. Calculate joint footage, mortar volume, whole bags, labor hours and cost.

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Quadratic Graphing Calculator — Vertex, Roots & Steps

Type a quadratic function to graph and solve it instantly, or edit standard, vertex and root forms. Trace the parabola and see roots, vertex, domain, range and steps.

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Water Volume Calculator — Area, Depth & Gallons

Calculate US gallons from square feet and water depth, then plan pools, ponds, tanks, materials and volume conversions with editable examples.

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Heat Loss Calculator — Walls, Windows & Air Leakage

Estimate design heat loss through walls, windows, ceiling, floor and air leakage, with an editable BTU/h and kW breakdown.

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EV Charging Calculator: Time, Cost and Home Charger Size

Calculate EV charging time, wall energy, session cost, range added, home charger size and annual savings versus gasoline.

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Rainwater Harvesting Calculator — Tank Size & Daily Balance

Compare rainwater tanks using a storm and dry spell or your daily rainfall data. See water supplied, shortages, overflow and the reserve left each day.

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VAT Calculator — Add, Remove & Find VAT

Add VAT to a net price, remove VAT from a gross total, or find the effective VAT rate with currencies, rounding, formulas, and a clear tax breakdown.

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Wallpaper Calculator — Rolls, Pattern Repeat & Cost

Estimate wallpaper rolls for rooms or separate walls. Account for strip rounding, trim, straight or half-drop repeat, reserve, reusable offcuts, leftover length, and cost.

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