All Field Calculators
Straightforward, manual-entry calculators for the numbers permaculture, farm, and off-grid energy projects actually run on — swale volume, mulch quantity, terrace spacing, solar and hydro sizing, and more. Every one of them uses a real, published formula (not an invented rule of thumb), and none of them need a site pin, an account, or a live map lookup — you type in what you already know or can measure, and get a real answer back instantly.
Why manual entry, not auto-fetched site data?
Swales' map-driven tools (Solar Potential, Wind Potential, RainAdvisor) already pull real data for a pinned location. These calculators are the opposite on purpose: no external data source to fail, time out, or drift out of date — you control every input, so the reliability of the answer only depends on the reliability of the numbers you put in.
How to measure your own inputs
Most inputs here are things you can get with a tape measure, a level or clinometer app, or a simple bucket-and-stopwatch test — slope percent (rise over run x 100), catchment area (length x width of the roof or surface draining into your swale), flow rate for hydro (time how long a container takes to fill, divide volume by seconds). Each calculator's own page explains exactly how to get its specific inputs.
What these numbers are good for
Sizing before you dig, order materials, or buy equipment — catching an order that's 3x too small or a turbine that's undersized before it costs you money, not after. For anything that becomes a permanent structure (a dam, a large terrace system), treat these as a solid starting estimate and get a site-specific professional check before final construction — see Professional Services for that.
Earthworks & Permaculture
Swale Volume & Dimensions Calculator
Work out a swale’s volume from its depth and width, or the trench length you need to hit a target volume.
Terrace Spacing Calculator
Vertical interval and spacing between bench terraces on sloped ground, from slope percent and soil type.
Mulch Calculator
How much mulch you need for an area and depth, in cubic metres, cubic yards, and standard bags.
Rainwater Harvesting Tank Size Calculator
Size a collection tank from your roof or hardscape catchment area and local rainfall.
Compost C:N Ratio Calculator
Balance browns and greens by weight to hit a target carbon-to-nitrogen ratio.
Pond & Dam Volume Calculator
Estimate stored volume and surface area for a pond or small dam from its dimensions.
Keyline Plow Line Layout Calculator
How many parallel plow lines your paddock needs from your chosen implement spacing.
General Agriculture
Soil Amendment Rate Calculator
Convert a per-hectare or per-acre application rate into the exact quantity for your plot.
Seed Rate & Plant Population Calculator
Plants per area and seed quantity needed from row spacing and in-row spacing.
Grazing Stocking Rate Calculator
Animal units your pasture can support, from forage production and paddock area.
Vertical Farming
Daily Light Integral (DLI) Calculator
Total daily light delivered to a grow space from PPFD and photoperiod, checked against per-crop targets.
Nutrient Solution Dosing Calculator
Scale your product’s full-strength dose to your reservoir size and growth stage.
Vertical Farm Tier Yield Estimator
Expected yield from tray count, tiers, and turns per year for a given crop.
Microgreens
Aquaculture & Aquaponics
Fish Stocking Density Calculator
Safe stocking density by species and system type, from tank or pond volume.
Aquaponics Fish-to-Plant Ratio Calculator
Grow-bed area to match your fish stock’s feeding rate in a balanced aquaponic system.
Dissolved Oxygen & Aeration Calculator
Aeration capacity needed to keep dissolved oxygen safe for your fish biomass and temperature.
Energy
Solar PV Array Size Calculator
Panel wattage needed to cover a daily load, from your local peak sun hours and system efficiency.
Micro-Hydro Power Output Calculator
Power output from head height and flow rate — the standard hydropower formula, by turbine type.
Off-Grid Battery Bank Size Calculator
Battery capacity (Ah) needed for a target autonomy, depth of discharge, and system voltage.
Inverter Size Calculator
Inverter rating needed for your peak simultaneous load, with a safety margin.
Wind Turbine Output Calculator
Estimated annual output from a turbine’s rated power and your site’s average wind speed.
Solar & Wind ROI / Payback Calculator
Years to payback from system cost, electricity price, and expected annual generation.
Biogas Potential Calculator
Estimated biogas yield from organic waste volume and volatile solids content.
Hybrid Off-Grid System Load Balancer
Combine solar, wind, and hydro contributions against your load to size a complete hybrid system.