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Full Calculator Library
Don't worry, you're in the right place. Bush & Bench is the home of our family of free sites, and this is our family calculator library: every calc from all our sites, grouped by topic, free to use.
Off-Grid 12V
Camping, caravan and 4WD power.
Solar
Solar Charging Check
Compare your daily solar with your daily use, and see roughly how much solar would balance it.
Open calculator →Solar Panel Sizing
Work out how many watts of solar panels you need to cover your daily use, and how many panels that takes.
Open calculator →Wiring & Charging
DC-DC Charger
Estimate the DC-DC charger size to recharge your auxiliary battery while driving, with input current and alternator load.
Open calculator →Charger & Inverter
Work out the charger current needed to refill your battery in the time you have.
Open calculator →Voltage Drop
Estimate the voltage drop and power loss on a DC copper cable run.
Open calculator →Cable Size
Find the smallest copper size that meets a voltage drop target. Voltage drop only.
Open calculator →Fuse Size
Find a starting fuse size from your load, and check it isn't bigger than your cable can carry.
Open calculator →Batteries
Battery Sizing
List what you run each day to get your daily energy use in Wh. It also sizes the battery in step 2.
Open calculator →Battery Runtime
Estimate how long a battery or portable power station will run a load, from its Ah or Wh rating.
Open calculator →Battery Charging Time
Estimate how long a mains, DC-DC or solar charger takes to bring your battery from one charge level to another.
Open calculator →Series & Parallel
Work out the voltage, capacity and energy of batteries wired in series, parallel or both, and how many you need.
Open calculator →Fridge Power Draw
Estimate how much power a compressor fridge uses each day, and how many days your battery could run it.
Open calculator →Power Station Runtime
Estimate how long a portable power station will run your 240V AC and 12V or USB loads, allowing for inverter losses.
Open calculator →Trip Planning
Camping Trip Power Budget
Bring your daily use, battery and charging together to see whether they could cover the whole trip.
Open calculator →Check My System
Answer a few questions about your existing 12V gear and get a checklist of what to confirm.
Open calculator →Home & Shed Solar
Solar for the house, shed and workshop.
Daily Power Needs
List what you run in your home, shed or workshop and work out the daily energy (kWh) and peak load your solar system has to supply.
Open calculator →12V / 24V / 48V Picker
Enter your biggest inverter load and daily energy to see the battery current at 12V, 24V and 48V, and which system voltage suits your shed, workshop or home.
Open calculator →Solar Array Size
Work out how many watts of solar panels you need from your daily energy use and winter peak sun hours, and how many panels that is.
Open calculator →Inverter Size
List the tools and appliances you run at once, allow for motor start-up surge, and find the inverter size and battery current for your workshop or shed.
Open calculator →MPPT Controller Size
Enter your panels and battery voltage to find the MPPT charge controller current and the cold-morning panel voltage it must handle.
Open calculator →Solar Payback
Use your own quote, bills and feed-in tariff to estimate how long a home solar system takes to pay for itself, or compare an off-grid shed with a cable run or generator.
Open calculator →Cordless Tool Batteries
Looking after tool packs on the bench.
Pack Runtime
Estimate how long a cordless tool battery will run your tool, from the pack's volts and amp-hours (Ah × V = Wh).
Open calculator →Pack Charge Time
Estimate how long a cordless tool battery takes to charge, from the pack's amp-hours and the charger's output current.
Open calculator →Rebuild or Replace
Compare the cost of rebuilding a cordless tool battery with new cells against buying a replacement pack.
Open calculator →Cell Layout
Work out the series and parallel cell layout of a cordless tool battery, its voltage, capacity and current, with a plain-text diagram.
Open calculator →Electrical Basics
The basics behind every circuit.
Ohm's Law
Enter any two of volts, amps and ohms to work out the third, plus the power in watts.
Open calculator →Watts, Amps & Volts
Work out watts from volts and amps, amps from watts and volts, or volts from watts and amps, for DC or 240V AC.
Open calculator →Wire Gauge (AWG & mm²)
Turn AWG (B&S) sizes into copper cross-section in mm², or mm² into the nearest AWG, with a size chart.
Open calculator →mAh, Ah & Wh Converter
Change mAh to Ah and Wh, or Wh back to Ah and mAh, using the battery's nominal voltage.
Open calculator →Farm & Yard
Water, fencing and building jobs around the farm.
Water Tank Size
Work out how big a rainwater tank you need to get the house, garden and stock through a dry spell, in litres and number of tanks.
Open calculator →Roof Rainwater Catch
Work out how many litres of rainwater your roof can catch from a storm, a month or a year, and how long it would last.
Open calculator →Pump Size
Work out the flow and total head a water pump needs to lift water from a tank, bore or dam, and roughly how many watts it will draw.
Open calculator →Electric Fence
Work out how much live wire an electric fence needs, the insulators and rolls to buy, and a rough energiser size to start from.
Open calculator →Fencing Materials
Work out the posts, strainers, stays, wire and mesh rolls for a farm or yard fence from the length of each side.
Open calculator →Concrete & Area
Work out the area and concrete volume for a slab, path or pad and for post holes, and how many premix bags you need.
Open calculator →These calculators are educational planning estimates, not a complete system design. Each one lists what it does and doesn't take into account.