How to use this calculator
- Enter the total prepared buffer batch volume.
- Enter the nominal buffer volume used by each sample.
- Add a per-sample pipetting allowance and fixed reserve.
- Calculate the number of complete samples supported.
#3298 · Science & Engineering Tool
Buffer Preparation Sample Capacity Calculator
Estimate how many samples a prepared buffer batch can support after reserving dead volume and quality-control volume. Enter batch volume, buffer required per sample, fixed reserve, and optional overage per sample. The calculator reports complete-sample capacity, usable volume, total consumption, and leftover buffer.
Calculator
Usable buffer allocationFormula
Adjusted volume per sample = nominal volume × (1 + overage)
Usable volume = batch volume − reserve
Capacity = floor(usable volume ÷ adjusted volume per sample)
Usable volume = batch volume − reserve
Capacity = floor(usable volume ÷ adjusted volume per sample)
What the result means
The main result is the number of complete sample allocations the batch supports without consuming the fixed reserve.
Capacity is volume-based. It does not account for reagent stability, container limits, sterility, or protocol-specific maximum hold time.
Example calculation
From a 500 mL batch with 20 mL reserved, 480 mL is usable. At 2 mL per sample plus 10% overage, each sample consumes 2.2 mL, supporting 218 complete samples with 0.4 mL usable buffer left.
Tips for better results
- Measure actual dead volume for the dispensing setup.
- Separate fixed reserve from percentage overage.
- Round capacity down to complete samples.
- Include control and blank wells as sample equivalents when they consume buffer.
- Prepare within validated stability and storage limits.
Frequently asked questions
Why is capacity rounded down?
A fraction of a sample cannot receive its full required buffer volume.
Should controls count as samples?
Yes. Include every control, blank, standard, or repeat that consumes the same buffer allocation.
What belongs in fixed reserve?
Examples include instrument priming volume, QC testing, container heel, and contingency volume held back.
Can overage be zero?
Yes, but zero assumes no pipetting, transfer, or container loss.
Does leftover include the fixed reserve?
No. The displayed leftover is from usable volume; the fixed reserve remains separate and untouched.
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Variables and units
| Variable | Meaning | Unit |
|---|---|---|
| Vbatch | Total prepared buffer | mL |
| Vreserve | Fixed held-back volume | mL |
| Vs | Adjusted volume per sample | mL/sample |
| floor | Rounds capacity to complete samples | whole samples |