Crop Water Requirement Calculator.
Estimate ETc, net and gross irrigation depth, peak daily volume, storage and design pump flow for a commercial project. Supplier-neutral scoping tool — confirm with local ETo data and a hydrological study.
How do you calculate crop water requirement (ETc)?
Crop water requirement is ETc = ET0 × Kc, where ET0 is reference evapotranspiration for the location and Kc is the crop coefficient for the growth stage. Net irrigation adds effective rainfall and system efficiency.
- Formula: ETc (mm/day) = ET0 × Kc; 1 mm over 1 ha = 10 m³ of water.
- Kc typically ranges 0.3–0.5 (initial) to 1.05–1.20 (mid-season).
- Gross demand = (ETc − effective rain) ÷ irrigation efficiency (drip ≈ 0.90).
- Peak daily demand sizes the pump, filtration and mainline, not average demand.
Estimate only — not a quotation. Outputs are indicative planning ranges based on the values you enter and typical commercial benchmarks. Real pricing, specifications and lead times vary by country, site conditions and supplier, and are confirmed only in written offers collected through a private RFQ.
Site and system inputs
Peak-month average from the nearest station
Crop coefficient Kc = 1.15
Drip 85–92 · pivot 75–85 · surface 50–65
Indicative only. Local ETo, soil water holding capacity, salinity leaching fraction and abstraction licences change these numbers materially.
Result in plain language
For 20 ha at a reference ETo of 6 mm/day and Kc 1.15, the crop uses about 6.9 mm/day. After 0.5 mm/day of effective rainfall and 88% system efficiency, the system must deliver about 1,454.5 m³ on a peak day — a design flow of about 90.9 m³/h over 16 pumping hours. This is a planning estimate, not an irrigation design or a supplier quote.
Method source
The method is the single crop coefficient approach (ETc = Kc × ETo) in FAO Irrigation and Drainage Paper 56, Crop evapotranspiration (Allen, Pereira, Raes and Smith, FAO, Rome, 1998). The four stage coefficients used here (0.4, 0.75, 1.15, 0.8) are generic planning defaults set by SeedMatch, not crop-specific values: replace them with the crop's values from FAO-56 Table 12 or local research, and take ETo from the nearest weather station.
Turn this estimate into a project brief
Send these figures to the greenhouse RFQ form. Your inputs and results are attached to the brief, a sourcing specialist reviews it, and only then are suitable suppliers or project partners approached.
Buying more than once? Save these project details to your buyer profile so your site, crop, budget and timeline are pre-filled on every future request.
Indicative only. Not financial advice, not agronomic advice, not engineering design. Final numbers require supplier, agronomist, engineer and local regulatory review.
Turn this estimate into a qualified project
SeedMatchGroup is a supplier-neutral, human-led platform. We do not manufacture or resell equipment — we help buyers specify the project, review relevant suppliers privately and compare the written offers received. Supplier participation and timing are not guaranteed.
Send these numbers to the RFQ Builder
The numbers below were calculated with SeedMatchGroup's Crop Water Requirement Calculator. Indicative — the specialist will confirm scope before contacting suppliers.
20 inputs · assumptions · results
Frequently asked questions
ETc = ETo × Kc. Reference evapotranspiration (ETo, mm/day) is multiplied by the crop coefficient for the growth stage, then effective rainfall is deducted and the net demand is divided by system efficiency to give gross irrigation depth.
Well-designed drip systems achieve 85–92%, micro-sprinkler 75–85%, centre pivot 75–85% and surface irrigation 50–65%. Filtration condition, pressure regulation and maintenance move a project several points within these ranges.
Annual volume sizes the water right and storage. Peak day sizes the pump, mainline, filtration and power connection — the equipment cost drivers in an irrigation RFQ.
No. It is a scoping tool. Licensed abstraction volumes, aquifer yield tests and water-quality analysis are required before a bankable design.
Turning this estimate into a request? The irrigation and fertigation request builder lists what changes a quote — system type, filtration, dosing and drain-water scope — and opens a pre-filled request that our team reviews before any supplier is contacted.
Understanding the values
What each choice in this calculator means, and how the options differ in practice.
- Reference evapotranspiration (ET₀)
- The water demand of a reference grass surface in your climate — the starting point before any crop adjustment. Hot, dry, windy sites have high ET₀.
- Crop coefficient (Kc)
- Adjusts ET₀ for your crop and its growth stage. A young crop uses a fraction of full demand; a full-canopy fruiting crop can exceed it.
- Effective rainfall
- The part of rain the crop can actually use. Only the effective portion reduces irrigation demand — heavy storms mostly run off.
- Irrigation efficiency
- Drip systems deliver most water to the root zone; sprinklers and furrow lose more to evaporation and deep percolation. Lower efficiency means pumping more water for the same crop need.
Illustrative project summary
1 ha multi-span tomato house
A new commercial entrant builds a first multi-span block with fertigation, insect screens and a basic climate computer.
1 ha · Multi-span polyhouse · Tomatoes
Indicative full greenhouse project CAPEX
USD 575K – USD 1.56M
Illustration only, not a real project or quotation. This is the structure, equipment and site-works budget for the example greenhouse, not the price of this calculator’s individual system, seeds or inputs, and not a result calculated from your entries. Excludes land, permits, packhouse, financing costs and working capital.
Based on the published commercial greenhouse cost benchmark. Written offers require a private project review; commercial projects start from USD 250K.
What can change the result?
This is a preliminary planning estimate based on the values you entered. The variables below usually move the outcome most, and should be confirmed with an agronomist, engineer and supplier offers before final design.
- Crop and cultivar — water, climate and support requirements differ per crop
- Local climate: temperature, humidity, radiation and wind exposure
- Irrigation design, emitter spacing and application efficiency
- Water quality and treatment needs (EC, pH, iron, hardness, pathogens)
- Growing system (soil, substrate, hydroponic) and plant density
Questions this calculator answers
Typical buyer and investor searches this tool is built for, including the markets where we run the most commercial projects.
- greenhouse water requirement and storage sizing per hectare for a commercial project
- greenhouse water requirement and storage sizing for a 2-hectare project — India
- greenhouse water requirement and storage sizing: indicative planning ranges — Kenya
- greenhouse water requirement and storage sizing benchmarks for investors — Saudi Arabia
- greenhouse water requirement and storage sizing under local market conditions — Mexico
- greenhouse water requirement and storage sizing — what to specify in a supplier RFQ
Method and decision path
How to use this result in a commercial project
Use the result to test scope and compare scenarios. It is not a design, agronomic prescription, financing offer or supplier quotation.
1. Enter site evidence
Replace defaults with measured area, climate, water, energy, crop and commercial assumptions.
2. Test scenarios
Change one assumption at a time and record the effect on capacity, cost, demand or return.
3. Validate the duty
Ask the relevant agronomist, engineer or financial adviser to check the inputs and constraints.
4. Prepare a private RFQ
Carry the confirmed scope into a human-reviewed brief so written offers can be compared on the same basis.
Final specifications, performance, prices, supplier participation and timing depend on the site and written supplier responses; none is guaranteed by this calculator.
Tell us five things and we route your brief
These fields decide which specialist and which suppliers see your request. Nothing is submitted here — your answers are carried into the private RFQ.
The USD 250K project threshold applies to capital projects. Recurring fertilizer programmes are reviewed by shipment size, annual volume and sourcing fit.
A sourcing specialist shortlists reviewed providers for your scope and returns comparable offers. Supplier details stay with us — all communication runs through SeedMatchGroup.
Estimate only: these figures are indicative planning numbers, not a quotation. Final pricing, specifications and lead times come from supplier offers after your brief is reviewed.
Plan the project around the numbers
A calculator output is a starting point. Pair it with the planning guides below to align timeline, irrigation, budget and risk before you launch an RFQ.
One private brief, specialist review, private supplier research and a like-for-like comparison.
Spec gaps, MOQ, delivery, Incoterms and evidence labels for seeds, greenhouses, irrigation, fertilizers and produce.
Month-by-month schedule from concept to first harvest across 9 stages.
Design principles for drip, pivot, fertigation and filtration on commercial projects.
How CAPEX, working capital and operating cost drive the project business case.
The ten most expensive planning and procurement pitfalls — and how to avoid them.
Procurement answers behind these numbers
A model output only holds if the scope, contract route and delivery terms match the assumptions. These reference answers cover the commercial decisions that move the figure.
- Turnkey EPC vs separate equipment packages
- What belongs in a greenhouse equipment specification
- Normal payment milestones in equipment contracts
- Which Incoterms to use for greenhouse and irrigation equipment
- How long a commercial greenhouse takes from order to handover
- What is normally the owner's scope on a greenhouse project
Move irrigation water supply and pumping into a structured RFQ
Editorial · not a sales pitchCalculator outputs are indicative. When your numbers stabilise, a supplier-neutral RFQ turns those estimates into a consistent brief for comparing the written offers that participating suppliers provide.
The facts a complete, supplier-neutral request on this topic includes. Use it as a checklist before submitting.
- Irrigated area, block layout and topography/elevation change
- Crop, spacing and peak daily water requirement (mm/day or m³/day)
- Water source (borehole, canal, reservoir, municipal) with yield and analysis
- System type: drip, sprinkler, pivot, micro-sprinkler, fertigation
- Required flow (m³/h), pressure and number of zones/shifts
- Power availability: grid, generator or solar pumping
- Automation and control level required
- Water analysis report and borehole test results
- Field/plot map with dimensions and elevation
Opens the RFQ Builder scoped as an irrigation package so suppliers quote hydraulics, filtration and dosing consistently. You stay in control — nothing is submitted until you review and confirm.
Free to submit · supplier-neutral · reviewed by a specialist before any supplier is contacted.
Running these numbers for a client project?
Agronomists, greenhouse and irrigation consultants use this calculator for feasibility, then hand the project to us for supplier shortlisting, RFQ preparation and quote comparison. You stay client-facing and we work through you.
Your client relationship stays with you — we work through you and never contact your client unless you ask.
Indicative only
- This tool is indicative only.
- It is not financial advice.
- It is not agronomic advice.
- It is not engineering design.
- Final numbers require supplier, agronomist, engineer and local regulatory review.
SeedMatch Group is an independent agricultural project sourcing and RFQ platform. We are not a farm, seed producer, fertilizer manufacturer, irrigation manufacturer, greenhouse builder, EPC contractor, lender or financial advisor. Supplier and project partner outreach is handled only after a commercial project brief is reviewed.
Supplier and manufacturer content is provided for research, transparency and discovery only. Buyers submit one project or RFQ to SeedMatch Group; our team validates and organises it, manages any suitable supplier or manufacturer outreach, and presents the responses through SeedMatch. There is no public directory of company identities, automatic matching, direct messaging or direct buyer-supplier contact.