GardenCalcs.uk
Crop Yield Calculator — Estimate Vegetable Harvest
Estimate harvest yields for common vegetables based on growing area.
Pick the vegetable to estimate — each uses average UK kg/m² yields and RHS spacing
Total bed or plot area given to this one crop, in square metres (e.g. a 2 × 3 m bed = 6 m²)
Scales the yield: beginner ~60%, average ~85%, experienced 100% of optimal
Fraction of optimal yield for beginners (default 0.6 = 60%)
Fraction of optimal yield for average growers (default 0.85 = 85%)
How We Calculate This
Yield = Area x Yield per m² x Skill Factor. Average yields are based on UK growing conditions with typical varieties.
Skill factors: beginner 60%, average 85%, experienced 100% of optimal yield.
Plant counts use recommended RHS spacings (e.g. potatoes and cordon tomatoes ≈ 0.25 m² each, courgettes ≈ 1 m², carrots and onions ≈ 0.01 m²). Harvest window shows how long the crop typically produces for.
Yield figures are average UK allotment kg/m² ranges (RHS grow-your-own guides, growveg.co.uk and gardenuk.co.uk) — for example tomato 5-10, courgette 5-8, potato 2-5, carrot 3-5 kg/m². Treat results as a planning estimate, not a guarantee.
Frequently Asked Questions
These are average UK yields for well-managed plots. Actual yields depend on soil quality, weather, variety, and how well you tend the crops. Experienced growers can exceed these figures.
Cordon tomatoes (around 6 kg/m²) and courgettes (around 5 kg/m²) are the highest-yielding crops here. Potatoes give good total weight (about 3.5 kg/m²) but need more space per plant. Leafy crops like lettuce yield the least by weight.
Good soil preparation, regular watering, proper spacing, timely feeding, and pest control all improve yields significantly.
Courgettes, runner beans, lettuce, radishes, and potatoes are all forgiving crops ideal for new growers in UK conditions.
Soil quality, consistent watering, sunlight (6+ hours), and feeding are the biggest factors. Protected growing (greenhouse/fleece) and succession planting also boost total harvests.
Related Calculators
Frost Date Planner
Plan your planting calendar based on last and first frost dates for common vegetable crops.
Raised Bed Vegetable Calculator
Plan what to grow in a raised bed with spacing and yield estimates.
Allotment Planner Calculator
Plan crop rotations and plot layouts for allotment gardening.
Runner Bean Calculator
Work out cane quantities, spacing, and expected yields for runner beans.
Courgette Spacing Calculator
Calculate courgette plant spacing and expected yields.
Was this calculator helpful?
One tap. Votes are anonymous and carry the page address, your device type, screen size and country, the numbers in the form and the results on screen, so we can check the answer you saw.
Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.