Frost Fleece & Floating Row Cover: Cut Width, Area, Rolls, Mass & Pegs for Beds

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 10 inputs are read from the form on every keystroke: Number of Beds, Bed Length, Bed Width, Growth Slack across the Bed, Edge Buried or Weighted, Each Side, End Buried or Gathered, Each End, Fleece Weight, Roll Width, Roll Length and Peg Spacing along Each Edge.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Rolls to Buy together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Cut Width of Cover, Roll Width Left Over (Negative = Too Narrow), Cut Length per Bed, Whole Cuts from One Roll, Fleece on the Beds, Mass of Fleece on the Beds, Fleece Bought in Whole Rolls, Bought Fleece Not on a Bed and Pegs for Both Edges — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

The beds need 1,754 m². Five rolls are 2,500 m², because the spare width and the roll ends do not fit another bed.

How to use it

1. Work through the input groups in order — Beds and Fleece & Fixing. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Rolls to Buy in the dark results panel — that is the headline figure, expressed in rolls.
4. Check the supporting rows underneath (Cut Width of Cover, Roll Width Left Over (Negative = Too Narrow), Cut Length per Bed, Whole Cuts from One Roll, Fleece on the Beds, Mass of Fleece on the Beds, Fleece Bought in Whole Rolls, Bought Fleece Not on a Bed and Pegs for Both Edges) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Rolls to Buy before a trial is booked, so machine time and material in Agrotextiles & Environmental Shielding are committed against a calculated figure rather than an estimate.
• Costing and quotation — Rolls to Buy is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Number of Beds) shows how much of the gap in Rolls to Buy each variable explains.
• Teaching and study — the accepted ranges bracket normal Agrotextiles & Environmental Shielding practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• Every dimension is the grower's or the label's; the tool has no figure of its own for slack, tucks or the fleece weight a crop or a frost needs. Each bed takes one cut of the cut length from a roll at least as wide as the cut width; a negative spare says the roll is too narrow and two widths would have to be joined. Rolls are counted by whole cuts, so the end of each roll that is too short for a bed is counted in the fleece bought but not on a bed. If one cut is longer than a whole roll, the count falls back to total length over roll length. Pegs run along both long edges at the spacing given, with one at each end of each edge. **This is a quantity take-off; it does not say how much frost a given fleece will hold off.**
• Every input is bounded to the range normal practice occupies (Number of Beds 1 to 10000 beds, Bed Length 1 to 2000 m and Bed Width 20 to 1000 cm, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• The supplier's data for the fleece: mass per square metre, light transmission and the UV stabilisation that sets how many seasons it lasts.
• Local horticultural advice on when to cover and uncover a crop, which no take-off can give.

Questions people ask