What you are given
- Gel percentage (%): 1
- Casting volume: 50 mL
Formula: agarose (g) = % / 100 · V (mL)
Gels
How much agarose do I need for a gel?
mass = (percentage / 100) x casting volume. A 1% gel in 50 mL is 0.5 g of agarose, dissolved in running buffer rather than water.
Worked example
Every number below is computed by the calculator, not typed in
The working
- Weigh-out formula:
mass = (% / 100) · V - Substitute:
mass = (1 / 100) · 50 mL=0.5 g - Buffer:
buffer ≈ V=50 mL
Weigh 0.5 g of agarose into 50 mL of buffer.
What each symbol means
- m: Agarose mass to weigh (g)
- P: Gel percentage (w/v) (%)
- V: Casting volume (mL)
Source: Agarose gel %w/v weigh-out. A printable one-page version is on the formula sheet.
Where this usually goes wrong
- Dissolving agarose in water instead of running buffer, which leaves the gel without ions and it will not run.
- Weighing after boiling. Evaporation during melting changes the percentage.
- Pouring above about 60 C, which warps the tray and kills the comb seal.
Try it yourself
Two problems, with the working revealed
Problem 1 Agarose gel
Work out the agarose mass and the buffer volume.
- Gel percentage (%): 1.5
- Casting volume: 250 mL
Show the answer and the working
Weigh 3.75 g of agarose into 250 mL of buffer.
- Weigh-out formula:
mass = (% / 100) · V - Substitute:
mass = (1.5 / 100) · 250 mL=3.75 g - Buffer:
buffer ≈ V=250 mL
Open this in the calculator to change the numbers.
Problem 2 Agarose gel
Work out the agarose mass and the buffer volume.
- Gel percentage (%): 2
- Casting volume: 75 mL
Show the answer and the working
Weigh 1.5 g of agarose into 75 mL of buffer.
- Weigh-out formula:
mass = (% / 100) · V - Substitute:
mass = (2 / 100) · 75 mL=1.5 g - Buffer:
buffer ≈ V=75 mL
Open this in the calculator to change the numbers.
Do it with your own numbers.
The Agarose gel calculator is free, shows every step, flags the hazards, and works offline once loaded. No account, no signup.
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