Resuspension Calculator
Resuspend lab materials fast — choose General (mass + MW + volume) or Oligo (DNA/RNA) (nmol + µM), pick what you want to solve for, and get volume, concentration, or mass with optional step-by-step.
Background
Resuspension means adding solvent (usually water, buffer, or TE) to a dry reagent to reach a target concentration or final volume. In General mode you’re using moles = mass / MW. In Oligo mode, vendors often provide the amount in nmol, and you typically target a convenient stock like 100 µM.
How to use this calculator
- Choose General or Oligo mode.
- Pick what you want to solve for (concentration, volume to add, or mass).
- Enter the inputs shown (units matter).
- Click Calculate to get the result + optional steps.
How this calculator works
- General: moles = mass / MW, then relate moles, volume, and concentration.
- Oligo: uses the standard conversion C(µM) = (nmol/µL) × 1000.
- The calculator converts units safely (mg↔g, µL↔mL↔L, µM↔mM↔M) before computing.
Formula & Equation Used
General concentration: C = m / (MW · V) (with m in g, V in L)
General volume: V = m / (MW · C)
General mass: m = C · V · MW
Oligo volume (µL): V = (nmol · 1000) / C(µM)
Oligo concentration (µM): C(µM) = (nmol / µL) · 1000
Example Problems & Step-by-Step Solutions
Example 1 — Oligo volume
You have 25 nmol of primer and want a 100 µM stock. How much water do you add?
- Use V(µL) = (nmol · 1000) / C(µM).
- V = (25 · 1000) / 100 = 250 µL.
- Answer: Add 250 µL to get ~100 µM.
Example 2 — General concentration
You dissolve 5 mg of a compound (MW = 180.16 g/mol) to a final volume of 10 mL. What is the concentration?
- Convert: 5 mg = 0.005 g, 10 mL = 0.010 L.
- C = m / (MW · V) = 0.005 / (180.16 · 0.010) ≈ 0.00277 M.
- That’s ≈ 2.77 mM.
Example 3 — General volume to add
You have 25 mg of NaCl (MW = 58.44 g/mol) and want a 0.10 M solution. What volume should you make it up to?
- Convert: 25 mg = 0.025 g.
- V = m / (MW · C) = 0.025 / (58.44 · 0.10) ≈ 0.00428 L.
- 0.00428 L = 4.28 mL.
Note: This calculator shows more digits; lab work typically rounds volumes to practical pipetting precision.
Frequently Asked Questions
Q: Is this the same as an “Oligo Resuspension Calculator”?
Yes — Oligo mode is exactly that. General mode is for non-oligo reagents.
Q: Why does the oligo formula use “× 1000”?
Because 1 nmol/µL = 1 mM, and 1 mM = 1000 µM.
Q: What units should I use?
General mode expects mass in mg/g and volume in µL/mL/L (the calculator converts internally). Oligo mode uses nmol and µM.
Q: Does it matter what solvent I use?
The math is the same, but in real lab practice your solvent choice (water/TE/buffer) depends on downstream use.
Q: Can I compute a working dilution (e.g., 10 µM from 100 µM stock)?
This page focuses on resuspension. For dilutions, use your Dilution Factor / Solution Dilution tools.
