Free tool
Grow-your-own savings calculator
Add the crops you plan to grow and how many plants of each, and we'll estimate how much you could save against buying the same veg from the shops.
Pick a crop, then set how many plants you'll grow.
Estimated annual saving
£99
£108 of veg, less about £10 in seed
| Crop | Plants | Yield | Shop value | Cost | Saving |
|---|---|---|---|---|---|
| Tomato | 4 | 12.0 kg | £48 | £3 | £46 |
| Runner bean | 6 | 9.0 kg | £32 | £3 | £29 |
| Lettuce | 6 | 1.8 kg | £11 | £2 | £9 |
| Courgette | 2 | 6.0 kg | £18 | £3 | £16 |
| Total | £108 | £10 | £99 |
Figures are conservative UK guidance only. Yields use realistic home-grow averages, shop prices are typical supermarket £/kg, and cost counts roughly one seed packet per crop — it ignores compost, pots, water and your time. A good year (or saving your own seed) can beat these numbers; a bad one will fall short.
How to use it
The calculator starts with a few popular crops already added. For each one, set how many plants you intend to grow this year. Add more crops from the drop-down, or remove any you won't be growing. The table and the headline estimated annual saving update instantly as you type — there is no button to press, and your choices are remembered on this device for next time. Lean towards the number of plants you'll realistically keep alive and harvest, rather than the number of seeds you'll sow.
How the calculation works
For each crop we multiply your plant count by a realistic UK home-grow yield per plant to get an estimated harvest in kilograms. That harvest is valued at a typical UK supermarket price per kilogram, then we subtract roughly one seed packet's cost per crop to give the saving. Adding those up across every crop gives your annual total. The figures are deliberately conservative: they use average yields, not best-case ones, and they ignore compost, pots, water and your time. The point is to show where growing your own pays off most — salad leaves, herbs, tomatoes and beans typically beat the shops by a wide margin, while cheap staples like maincrop potatoes and onions barely break even. Treat every number as guidance, not a guarantee, and use it to plan a patch that's worth your while.
Frequently asked questions
- How much money can you really save growing your own veg?
- It depends entirely on what you grow. High-value, fast-cropping plants like tomatoes, courgettes, salad leaves and runner beans can each save you several pounds a year, while cheap staples like potatoes and onions save very little against supermarket prices. A small bed of well-chosen crops can comfortably save £50–£150 a year once you're past the first season's setup costs.
- What costs does this calculator include?
- To keep it simple and conservative, it counts roughly one seed packet per crop and nothing else. It deliberately ignores compost, pots, water, tools and your time — so treat the headline figure as the value of the harvest minus seed, not a full profit-and-loss. Reusing pots, making your own compost and saving seed all push your real saving higher.
- Why are the yields lower than I expected?
- The yield-per-plant figures are realistic UK home-grow averages, not best-case allotment numbers. British weather, slugs, pests and a learning curve all take their toll, so we keep the estimates cautious on purpose. In a good year, with healthy plants and regular harvesting, you can easily beat them.