Allotment vs Supermarket ROI Calculator

Allotments are a tradition with genuine appeal — community, exercise, fresh produce. Whether they save money vs supermarket is more complicated than the romantic version suggests. At typical UK pricing: annual rent £50-£200, setup £200-£600, supplies £50-£150, plus 100+ hours of time. Produce value £200-£800 depending on productivity and what you grow. Numbers differ by country — switch currency in the selector and substitute your own local plot fees and produce prices.

The honest math: time dominates. 100 hours × £15 = £1,500 opportunity cost. Against £400 produce value, the allotment produces net -£1,100/year at that framing. Without time cost, net is often modestly positive — £200-£300/year after rent and supplies.

The reframe most allotment holders use: allotment is recreation that produces food, not a cost-saving strategy. The value calculation then flips — £100 net cost for 100 hours of outdoor exercise and community is £1/hour of recreation, excellent value. The tool supports both framings by letting you set the hourly value.

How to use it

Input annual allotment rent, setup cost (spread over lifespan if first year), annual supplies, honest hours per year, hourly value (set to 0 for pure hobby framing, real value for cost comparison), and estimated produce value. The tool calculates ROI.

What the result means

Positive ROI means allotment saves money accounting for time. Negative means it costs more than equivalent supermarket produce once time is valued. Most allotment holders show negative ROI on strict financial accounting but positive life value — which is a legitimate reason to continue.

Decision tool, not financial advice.

Which inputs matter most

You enter Annual Allotment Rent, Setup Cost (Annualised), Annual Supplies, Hours Per Year, and Hourly Value. Two inputs usually tip the answer one way or the other. Identify which ones matter most by flipping each value past a round threshold and watching whether the option with the lower calculated total changes.

What's happening under the hood

Net value is produce value minus all costs (rent, annualised setup, supplies, time opportunity cost). The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Reading a negative ROI

A negative number on the strict financial view doesn't mean the allotment is a mistake — it means the time cost exceeds the produce savings at the hourly value you set. That's a legitimate outcome for anyone who'd rather be doing paid work in those hours. For anyone who genuinely enjoys the gardening, setting hourly value to 0 gives the straight money comparison: cost of rent + supplies vs value of produce. That number is often positive. Neither framing is wrong; they answer different questions.

What this doesn't capture

Four things the tool leaves out on purpose: the exercise and mental-health value of being outside (well-studied but personal), the quality difference of home-grown produce (fresher, usually organic, varieties the shop doesn't stock), community benefit of a site-based allotment, and the learning curve — plots produce 30-50% less in year one. Factor those qualitatively when weighing the ROI number against whether to keep the plot.