Home & Everyday Calculators
Practical estimates for trips, energy bills, home projects, cooking and shopping, with waste allowances and assumptions you control.
Calculators
- Fuel Economy and Trip Cost Calculator
Trip fuel and cost in mpg (US or imperial) or L/100 km.
- Electricity Cost Calculator
Energy use and cost of an appliance from watts, hours and your tariff.
- Paint Calculator
Paint for walls after doors and windows, for any number of coats and coverage.
- Flooring and Tile Calculator
Boxes of flooring or tile with a waste allowance, pack rounding and cost.
- Concrete Calculator
Concrete for slabs, footings and columns in cubic yards or meters, with bag counts.
- Recipe Scaling Calculator
Scale ingredient amounts by servings, converting only between compatible units.
- Unit Price Calculator
Compare price per unit across package sizes and multipacks.
Which home and everyday calculator to use
These calculators turn measurements and prices you collect into quantities to buy and costs to expect. Prices, waste allowances and product details are left to you, because they vary by store and project.
- What will a trip cost in fuel?
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Fuel Economy and Trip Cost Calculator
Fuel used and cost from distance, fuel economy in any common unit and the price per gallon or liter.
- What does this appliance cost to run?
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Kilowatt-hours and cost per day, month and year from wattage, hours of use and your tariff.
- How much paint, flooring or concrete should I buy?
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Paint Calculator Flooring and Tile Calculator Concrete Calculator
Area or volume from your measurements, plus a waste allowance you set, rounded up to whole cans, boxes or bags.
- How do I scale this recipe?
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Multiplies each ingredient, rounds to kitchen-friendly fractions and converts units only within volume or within weight.
- Which package is the better buy?
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Price per ounce, liter, count or other common unit, ranked from cheapest.
Have these to hand
- Room dimensions, and the doors, windows or cut-outs to subtract.
- Coverage per can, box or bag from the product label.
- Your electricity price per kWh from a recent bill.
Mistakes that change the answer
- Entering a 4-inch slab as 4 feet, which orders twelve times too much concrete.
- Buying exactly the measured area with nothing extra for cuts, breakage and pattern matching.
- Converting cups of flour to grams. That needs the ingredient’s density, so the recipe tool will not guess.
- Comparing fluid ounces with ounces by weight when working out which package is cheaper.
Related guides
- Unit conversion pitfalls: gallons, tons, cups, GB vs. GiB
Nine unit traps with the numbers worked out: US vs. imperial gallons and pints, fluid ounces vs. ounces, three kinds of ton, cups of flour in grams, cup and tablespoon sizes, GB vs. GiB, bits vs. bytes, temperature changes and UK vs. US mpg.
- How much extra flooring, tile, paint and concrete to buy
Published rules of thumb for overage by material and layout, what each one covers, and worked examples that apply the allowance first and round up to whole boxes, cans and bags last.
- How to measure a room for square footage and volume
Measure, convert inches to decimal feet, split odd shapes into rectangles, then multiply and convert with a squared or cubed factor. Worked with an L-shaped room, a concrete pad and a water tank.
- Common percentage mistakes and how to avoid them
Six percentage slips that produce confident wrong answers, from percentage points to negative starting values, each worked with example numbers you can check.