Donaldson R F Free Home and Construction Calculators
Estimate materials and costs for paint, flooring, roofing, concrete, insulation and other home projects.
26 free tools in this category. No sign-up, no limits.
Paint Calculator
Calculate how much paint you need for a room.
Open tool →Concrete & Mortar Mix Calculator
Calculate concrete for a slab, plus cement and sand for a mortar mix ratio.
Open tool →Tile & Flooring Calculator
Calculate how many tiles you need for a room.
Open tool →Electricity Cost & Bill Calculator
Calculate an appliance running cost, or a whole bill including the standing charge.
Open tool →Wallpaper Calculator
Work out how many rolls of wallpaper a room needs, with doors and pattern repeat.
Open tool →Gravel, Mulch & Soil Calculator
Volume, weight, bags and cost of gravel, mulch, soil or sand for an area and depth.
Open tool →Roofing Calculator
Estimate roof area, shingles, panels or tiles, underlayment and ridge length.
Open tool →Fence & Deck Calculator
Estimate posts, panels, boards, joists and screws for a fence or deck.
Open tool →HVAC / BTU Calculator
Find the air-conditioner size a room needs in BTU/h, kW and tons.
Open tool →Solar Panel Savings Calculator
Estimate solar production, yearly savings, payback time and 25-year net savings.
Open tool →Brick Calculator
Work out how many bricks and how much mortar a wall needs.
Open tool →Battery Capacity & Runtime Calculator
Convert battery capacity between amp-hours and watt-hours, and work out how long a battery or UPS will run a given load for.
Open tool →Generator & Inverter Sizing Calculator
Add up appliance running and starting watts to work out the minimum generator or inverter size you need, with a safety margin.
Open tool →Rainwater Harvest Volume Calculator
Work out how many litres of rainwater a roof or catchment area can collect, from its area, the rainfall depth and a runoff efficiency coefficient.
Open tool →Air Changes Per Hour (ACH) Calculator
Work out air changes per hour (ACH) for a room from its volume and ventilation airflow rate, or the airflow needed to hit a target ACH.
Open tool →Stair Calculator
Work out the number of steps, riser height, going and pitch for a staircase, checked against UK Building Regulations Part K limits.
Open tool →Carpet Calculator
Work out how much carpet to buy for a room from a 4 m or 5 m roll, including waste, pattern repeat and cost. Metric or imperial.
Open tool →Power Factor Calculator
Work out power factor, apparent power (kVA) and reactive power (kVAR) for an AC electrical load.
Open tool →Plant Spacing Calculator
Work out how many plants fit a bed or row from its size and your plant and row spacing, plus packs to buy.
Open tool →Fertiliser NPK Calculator
Work out how much fertiliser to apply for a target nutrient rate, using the N-P-K grade printed on the bag.
Open tool →Garden Irrigation Water Calculator
Work out how many litres a garden or bed needs this week, from its area, a watering depth and any rainfall already received.
Open tool →Voltage Drop Calculator
Work out the voltage drop over a cable run from its length, cross-section, current and conductor material.
Open tool →Insulation Heat Loss Calculator
Work out the rate of heat loss through a wall, roof, floor or window from its U-value, area and temperature difference.
Open tool →Compost C:N Ratio Calculator
Work out the blended carbon:nitrogen ratio of your compost mix and see if it needs more greens or browns.
Open tool →Greenhouse Heating & Ventilation Calculator
Work out the heater wattage needed to keep a greenhouse frost-free, including glazing and ventilation heat loss.
Open tool →Growing Degree Days (GDD) Calculator
Work out cumulative Growing Degree Days from daily high/low temperatures and a base temperature.
Open tool →