Your real margin after GST, expiry write-off and the money tied up in stock — not just MRP minus what you paid. Runs entirely in your browser; nothing you type is sent anywhere.
Almost every published pharmacy margin figure is the trade convention — around 20% on PTR — and almost every one of them stops there. Two costs sit between that number and what actually reaches the till, and neither is optional.
This is the part that surprises people. When a unit expires you do not simply fail to earn its margin — you also lose the purchase price you already paid for it. So each expired unit destroys the profit of several sold ones.
At a 20% margin, every unit sold earns ₹15.87 on a ₹100 MRP pack. Every unit that expires loses ₹79.37. It takes five successful sales to pay for one write-off. That ratio, not the write-off percentage, is what makes expiry the dominant margin leak on slow-moving lines.
Whatever sits on the shelf was paid for out of working capital that could have bought something that moves. Holding it for 45 days at a 12% cost of capital is roughly 1.5% of its value — small per pack, and not small across a shelf.
| Expiry rate | Real margin on PTR | Share of headline margin kept |
|---|---|---|
| 0% | 18.5% | 92% |
| 2% | 15.7% | 79% |
| 5% | 12.5% | 63% |
| 10% | 7.0% | 35% |
| 16.7% | ~0% | 0% — breakeven |
Assumes 20% headline margin, 5% GST, 45 days holding at 12% cost of capital. Change any of those above and the table shifts — the calculator is the accurate version.
Expiry loss concentrates in slow movers, and slow movers are the hardest lines to see. A fast mover that turns weekly barely accumulates risk. A line that sells two packs a month can sit for a year without any single day looking wrong, and then be written off in one entry.
The two practical levers are dispensing the soonest-expiring batch first, and claiming returns inside the distributor's window rather than after it. Both require expiry recorded per batch — an item-wise stock record cannot support either.
The 20% retailer margin is a trade convention, not a statutory rate; DPCO price-controlled products and PCD arrangements differ. GST slabs on medicines were revised in September 2025. This calculator is a planning aid, not tax, pricing or accounting advice — reconcile against your own purchase invoices and books. As of August 2026.
The convention is ~20% on PTR, but that is the headline. After expiry and held capital the realised figure on a slow line is commonly a third lower. DPCO products carry less again.
Start from the ex-GST selling price — MRP is GST-inclusive and PTR is not — then subtract expiry write-off and cost of capital. Most published calculations stop at the first step.
More than the write-off figure: you lose the purchase price and the margin. At 20% margin it takes five sales to pay for one write-off.
About 16.7% at a 20% margin, before capital costs. Lower-margin products break even much sooner.
On PTR, ex-GST. Calculating on MRP mixes conventions and overstates the result. See the PTR / PTS calculator.
Usually GST not removed from MRP, expiry treated as a separate cost rather than a margin reduction, and returns posted as sales.
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Nesayo records the purchase rate and expiry against every batch, so margin and expiry exposure are already there rather than estimated — and expired stock is blocked at the counter instead of discovered at write-off. Billing is free, no invoice limit, no card.
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