How to Measure Lumens with a Lux Meter
Sponsored by JLCPCB ($2 for 10 Boards): https://jlcpcb.com
This is a difficult thing to do and my results weren't very convincing. But if you're interested in the theory, take a look :)
https://www.banggood.com/UNI-T-UT383-Digital-Mini-Lux-Light-Meters-Environmental-Testing-Equipment-Handheld-Type-Luxmeter-p-1080364.html?rmmds=search&cur_warehouse=CN
https://www.sainsburys.co.uk/shop/gb/groceries/light-bulbs/sainsburys-home-bulb-led-filament-standard-60w-bc-132041576-p