Polytunnel Cover Calculator

How big a sheet do I need?


Entering the information into our calculator will work out the size of sheet you will need in order to cover your structure. Watch the video to show how to measure for your replacement cover.

Should you know the size of sheet you need, or you simply wish to order polythene/net by the metre, please see our range of 'Polytunnel Covers'.

If you are still unsure as to what size of cover you require, please ring us on 01282 601253.

How Does Our Calculator Work?

Our calculator selects a width of polythene that spans the distance over polytunnel hoop (C) adding excess to accommodate enough material for burying in a trench (additional 2m) or fitting to base rails (additional 1m). We have fixed widths of covers, please note that certain covers have limited widths available and selecting one of these may result in excess material, ie our Super Therm has four widths to choose from, whereas our Green/White has only one.

In order to determine the length of material required, we multiply the height x 2, and add to this value to the length of the polytunnel. We round up to the nearest metre.

Useful Info....To convert metres to feet, multiply by 3.281. To convert feet to metres multiply by 0.305.

Trench/Base Rail

A - Length of Polytunnel
B - Height of Polytunnel
C - Distance over the Polytunnel Hoop

Is the polythene to be buried in a trench?

Enter your measurements below in either Feet or Metres...


Based on the values entered and allowing enough for the trench/base rails you require:

m x m

* We have fixed widths of covers available. Please find below options which accomodate your requirements. Please note certain covers have limited widths available and may result in excess material.

You may wish to change the length or width required, if so please enter a new value in the text box(es) above and click 'Calculate'. Would you like to know more about our polythene? View our polythene range.

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About First Tunnels

We’re a close-knit bunch of skilled professionals who take an enormous pride in the quality and versatility of our products, But we’re enthusiasts too - we use our own products, and that means we’ve introduced lots of improvements and innovations over the years…based on first-hand everyday practical experience. We work hand-in hand with top growing experts. We even have our own allotment for some seriously hands-on gardening, often accompanied by communal summer and winter barbecues because all work and no play would be very dull!

Polytunnel Community

Reviewed by you, Followed by you, Liked by you and listened to by us. We have a strong online polytunnel community, 35k Facebook Fans, 10k Twitter Followers and over 3m YouTube Views. Our community of dedicated, passionate Polytunnel gardening friends, love to share their sowing tips, growing hints and harvesting secrets with each other. But more importantly for you, as a customer or a potential customer, you can post your comments in all their glory or gory details. Come and join the Polytunnel family.

Construction Help & Advice

Our six man construction team has a wealth of polytunnel construction knowledge and are more than happy to share tips and advice with any of our customers. Many of the team have been quite literally 'hands on' developing the First Tunnels vast array of construction videos and in depth instruction guides. Our construction team are available to answer your questions and help in whatever way they can. Simply call 01282 601253 on week days between 9am-5pm...PLUS weekend cover on 07801 601253, between 9am-5pm.

Frequently Asked Questions

We are proud of our products and the time that we have put in to making sure that all our products are first class. We understand that purchasing a polytunnel is a considerable investment, and whilst we have lots of help and advice on this site, Facebook, YouTube, Twitter and blog pages many people like to compare and contrast before they commit their hard earned cash to buying. To this end we have compiled a list of the most common questions and provide 10 top reasons why First Tunnels Polytunnels is the top choice.

Getting Growing

Part of the fun of owning a polytunnel is picking the brains of people who really know how to make the most of the real growing potential. So we're making it easy for you...with some of the best brains in the business! This site now includes features, produced exclusively for First Tunnels by Andy McKee and Mark Gatter - best-selling authors of 'How to grow food in your Polytunnel' and 'The Polytunnel Handbook'. We also have videos from BBC’s Gardeners’ Question Time presenter, Paul Peacock. We also have a host of growing guides from Sam Youd, presenter & judge for the Royal Horticultural Society & Tatton Park Head Gardener.

Other Useful Stuff

What better way to learn about company dependability, product quality and customer service than to hear it straight from other consumers? By giving customers the opportunity to share their First Tunnels shopping experience, we believe this is the best reflection of our companies’ product and service. To help reinforce credibility, popularity and reputation, we have subscribed to not one, not two...but THREE independent review companies. We value all feedback, good, bad or ugly and hope to build a long lasting relationship with our customer, through our high quality products and friendly service, to ensure they do not hesitate to order again and again with First Tunnels in the future.