Update: Measured again with a $20 metal manual caliper (never calibrated), wrench was ~13.0 mm, hex keys were ~8.0 mm, ~6.0 mm, and ~4.0 mm.
Tried to measure the sizes of old Allen or hex keys, and a wrench, that should be from Ikea. Used a really cheap manual caliper made of plastic and tried estimating the sizes of the Allen keys between opposing faces. Hex keys should have come with various Ikea furniture pieces over the past few years. Caliper never calibrated after purchase, only checked against an even cheaper plastic ruler. Unsure if the key/wrench measurements were supposed to be imperial or metric sizes. Both mm and converted size in inches shown.
Reminder: Accuracy not guaranteed. These are NOT instructions. Do NOT try this yourself.
Post time: Apr-18-2017