Ruler is useless on newer iPhones – Handy Tool Set for Daily Use - 6 in 1 Toolkit with Compass, Flashlight, Ruler, Magnifying Glass ( magnifier ), Mirror and Arc Protractor ! Review

This would be a good tool except it apparently hasn't been updated for the iPhone 6. At least that seems like the best explanation for the ruler reading 20% too low. That's right: 5cm reads as 4cm, 1.25" reads as 1", etc. No idea if it works any better on earlier iPhones with smaller screens, but it's useless to me. The other tools are ok but there are plenty of other apps that have those and accurate rulers.
Review by wjz7 on Handy Tool Set for Daily Use - 6 in 1 Toolkit with Compass, Flashlight, Ruler, Magnifying Glass ( magnifier ), Mirror and Arc Protractor !.