A measuring cylinder (graduated cylinder) is the everyday volume tool between a rough beaker and an exact volumetric flask — ideal when you need decent accuracy without full-precision measurement. This guide covers correct reading technique, EX vs TC, accuracy classes, and precautions.
Read at eye level with the bottom of the meniscus, with the cylinder standing on a level surface. A measuring cylinder is a to-deliver (EX) instrument — the volume poured out equals the scale reading, so fill to the mark and pour.
1. Types & Correct Reading
1.1 Stopper Options
- Plain cylinder: the common open-top type, easy to pour and clean.
- Stoppered cylinder: with a glass or plastic stopper, for volatile liquids or mixing by inversion.
1.2 Three Steps to a Correct Reading
Place the cylinder upright on a level surface and wait for the surface to settle (no bubbles, no cling).
Read at eye level with the bottom of the meniscus for transparent liquids (read the top of the convex surface only for non-wetting liquids such as mercury).
Reading above the mark gives a high value, below gives a low value. Estimate to 1/2 or 1/5 of the smallest division (e.g. a 100 mL cylinder with 1 mL divisions reads to ~0.2 mL).
2. EX vs TC
| Marking | Meaning | Basis | Typical Instrument |
|---|---|---|---|
| EX (to deliver) | Volume poured out = scale value (wall cling already deducted) | Pour out to the mark | Cylinder, burette, pipette |
| TC (to contain) | Volume contained = scale value | Fill to the mark | Volumetric flask |
Most measuring cylinders are EX: fill to the mark, pour out — the poured volume is the reading. Do not "shake dry" the last drop; the cling film was already allowed for in calibration.
3. Sizes & Accuracy Classes
- Common sizes: 5, 10, 25, 50, 100, 250, 500, 1000, 2000 mL.
- Classes: Class A (small tolerance, for analysis) and Class B (routine). Class A 100 mL ±0.5 mL, Class B ±1.0 mL.
- Rule of thumb: pick a cylinder close to the volume you need — one pour, small divisions. Don’t measure 30 mL in a 500 mL cylinder.
4. Cylinder vs Volumetric Flask vs Beaker
| Vessel | Accuracy | Best For |
|---|---|---|
| Beaker | ±5% | Rough addition, dissolving, heating |
| Measuring cylinder | ±0.5–1% | Reagent volumes, approximate solutions |
| Volumetric flask | High (100 mL ±0.08 mL) | Making up standard solutions |
| Pipette / burette | High | Exact transfer / titration metering |
5. Precautions
- Never heat a cylinder — thin walls and printed scales deform with heat; no open flame, no oven drying (brief 60°C max).
- Do not prepare solutions in it — dissolving solids or diluting concentrated acids generates heat and is hard to mix safely.
- No strong alkali or HF — alkali frosts the glass and HF dissolves it; use a plastic cylinder instead.
- Pour along the wall or a rod; clean with a soft brush and detergent — never steel wool.