Monthly requirement
How much do you actually need per month?
Most resellers under-order water, and it isn’t carelessness — it’s that nobody does the arithmetic until the shelf is empty. Enter your throughput and draw volume and this gives you a monthly figure.
The arithmetic
One 10 mL vial yields ten 1 mL draws, or five 2 mL draws. At a 2 mL draw, a 10 mL vial covers five units. A reseller shipping 1,000 units a month therefore needs roughly 200 vials of 10 mL solution — before buffer, and before breakage.
Why add a buffer
Multi-dose vials have a working life from first puncture, not from delivery. Some volume is always lost to that clock rather than to draws. {{FILL: buffer %, e.g. 15}} is the figure we’d plan against.
Volume questions
The arithmetic behind the figure above, and what to do with it once you have one.
How many draws does each vial size give?
Divide the fill by the draw. At the two most common draw volumes:
- 3 mL — three draws at 1 mL, one at 2 mL
- 10 mL — ten draws at 1 mL, five at 2 mL
- 30 mL — thirty draws at 1 mL, fifteen at 2 mL
That is arithmetic on the fill volume and nothing more. Which draw volume your process uses is a question for your process — the calculator asks for it, it does not supply it.
How many vials does a reseller shipping 1,000 units a month need?
At a 2 mL draw, roughly 200 vials of 10 mL a month — before buffer and before breakage.
The working: 1,000 units at 2 mL is 2,000 mL, and 2,000 divided by 10 is 200. The same requirement is 67 vials at 30 mL. Both land well past the 100-vial break, so the arithmetic that matters is not whether you qualify for Tier 2 but how often you reorder.
How do I turn the monthly figure into an order?
Multiply by the months of cover you want to hold, add your buffer, then check the total against the 100-vial break.
The break is assessed per order, not per month, so cover length is a pricing decision as well as a stock one: an account needing 60 vials a month is one month of extra cover away from paying 20% less per vial. Two separate sixty-vial orders get no discount at all. The tier table, or set the quantities and send the order.
Which size is cheapest per mL?
The 10 mL and the 30 mL are identical per mL — $0.90 at Tier 1 and $0.72 at Tier 2 — so between those two the choice is handling rather than price.
The 3 mL costs more per mL and exists to buy in at the smallest increment; it suits an account shipping single units rather than stocking a bench. Fewer, larger vials means fewer closures opened per unit volume, which is the real trade-off between the 10 mL and the 30 mL. The full per-mL table.
Why does the calculator ask for mL drawn rather than for units?
Because the draw volume is a number your process already has, and it is not a number we are going to supply.
This is an inventory planning tool. It converts a throughput you know into a purchase quantity, and it does not recommend a draw volume, a ratio or a method. We publish no reconstitution guidance and no dosing guidance of any kind — that is the line between supplying a laboratory reagent and directing its use. Why we hold that line.
Does the figure include freight or tax?
No. It shows vials and vial cost at published prices, nothing else.
Freight is quoted per order on the size of the shipment and its destination, and tax depends on the ship-to state and whether you hold a resale certificate. Both appear on the written quote rather than being estimated here, because an estimate that is wrong is worse than a line that says it is not included. Account terms · taxes and freight.
This is an inventory planning tool. It does not recommend a draw volume — it asks for the one your process already uses. For research use only. Not for human or veterinary use.