Why a seasonal pattern is not a promise
Onion prices often move with harvest arrivals, stored stock, regional demand and the quality reaching a particular mandi. A large fresh arrival can put pressure on a local price, but a crop problem elsewhere, movement of trucks, restrictions or weather may change the picture quickly. A useful historical chart needs the same commodity, grade, market and measurement unit as your crop. A state-level headline price cannot substitute for the amount a buyer will pay for your specific lot after grading and deductions. The date you choose to sell matters, but so do the place and the quality delivered on that date.
Read daily reports carefully
AGMARKNET publishes market-wise daily reports of arrivals and prices. The modal price is a reported market statistic, not a guaranteed bid for every seller. Look at a run of dates rather than one unusually high or low observation. Compare nearby mandis after accounting for freight, commissions, time and payment terms. A difference of ₹200 per quintal can disappear if moving to another market costs as much after fuel and handling. Also check whether the report lists the same type and quality of onion that you plan to deliver. If a report is missing or delayed, do not fill a gap with a guessed price.
To build a small local notebook, write the report date, mandi, arrivals, minimum, maximum and modal price, and your own offered sale rate. These columns let you compare an official market report with what you could actually realize. Note important changes in your lot's grade over time. The article does not give a national historical price series because no single series represents every buyer and market. For a decision made today, use a current report and obtain a current offer. Historical data can frame a range; it cannot make a forward price certain.
The harvest-arrival connection
Many sellers reach a mandi within a similar harvest window. When arrivals are heavy, buyers have more supply to choose from. Some farmers then consider storage, hoping a later sale will earn more. That choice also removes money from their hands today and exposes the crop to shrinkage and spoilage. A later period with fewer arrivals might support prices, but stored onions from many farms can reach the market together. The total supply at that future date is hard for one farmer to know. Avoid treating “prices rise after harvest” as a rule that automatically makes storage profitable.
Build a break-even range instead of one forecast
Start with a real present offer and add the full cost of holding the crop. The calculator's break-even price is the later per-quintal amount needed to produce the same net value as selling immediately. It divides today's sale value plus rent, capital cost and extra transport by the quantity expected to remain saleable. Shrinkage and spoilage reduce that denominator. A higher expected future price does not guarantee a profit if the crop loses too much quantity or the buyer cuts the grade. Run a low, middle and high later-price scenario rather than relying on a single point estimate.
For example, suppose today's price is ₹2,000 per quintal and your break-even after storage works out to ₹2,600. A later offer of ₹2,500 would still leave storage behind selling now, even though the headline mandi price increased by ₹500. An offer of ₹2,800 could be better on paper, subject to the amount and grade actually sold. Those figures are hypothetical and illustrate the logic, not a prediction about a future month. If your immediate sale also has freight that the calculator does not ask for, compare both sale routes on the same basis by entering only the extra freight caused by storing.
What may disrupt a price expectation?
Weather can affect harvest timing and roads. Pest and disease problems can reduce marketable output. New arrivals from other growing areas can shift supply; changes in storage release can shift it again. Prices quoted online can be old by the time trucks arrive. Government measures and trade conditions can also influence the market, and their details may change. Check a current official notice before relying on any specific rule. Do not use last year's best month as the only basis for this year's decision; a high observed price is not an available contract.
Use the notebook after selling
Record the actual weight sold, deductions, freight and cash received. Compare those figures with your estimate. If you stored the crop, calculate the final return per starting quintal, not only the headline sale price per surviving quintal. A farmer who sold fewer quintals at a higher price might still earn less overall. Repeating this comparison over seasons teaches you which assumptions on rent, loss and buyer grade need correction. It also makes the calculator a decision aid rather than a promise printed on a screen. Talk with local agricultural advisers and market participants when conditions change.
Sources and further reading: NHRDF onion information; NHRDF post-harvest technology for onions; AGMARKNET official market price portal. These sources explain storage considerations and offer market reports. They do not certify this calculator’s default rates or predict future prices.