You've designed that beautiful big 3D part, sliced it expertly, set the printer going, and watched the first few layers. Great now all you have to do is wait for 48Hrs! Then two days later, with the print head nearly winding itself off the top of the printer, and the screen telling you that your masterpiece is at 98% you notice with horror that there is only a foot of filament left on the reel!
This has happened to me.
So now I have an Excel spreadsheet to work out if I have enough left, by weight, to print my part. I've weighed an empty reel complete with it's spindle. I've done this for every brand of filament I use. Incidentally, Surreal, 3DJake, BasicA, and not tried yet YOYI.
Then when I slice the model, in Cura, it tells me how much it should weigh. I've found this number to be quite accurate, unlike it's estimate of print time which is usually 30% light.
I weigh the reel on the printer, with a kitchen scale. I type that number into the spreadsheet and it takes away the weight of the empty reel and spindle, giving me the actual amount of filament left. I've built in a 2% margin of error to be on the safe side.
So if the filament on the reel is more than the estimated weight of the model, I'm good to go.