Have a FTP test coming up in the next few days.
I was wondering what everyone on here (or TR) recommend using as your weight to work out your w/kg.
By this is mean, do you use your …
• weight that day?
• avg of week?
• avg of last 4 weeks?
• avg of last 6 weeks?
My weight tends not to fluctuate too much but it does a little and i would be interested to hear what everyone else does …
thanks! 
I do my Ramp Test in the morning as I do my workouts in the mornings as well, so on Ramp Test Day I get up, go the bathroom, then weigh myself. I then get dressed, drink some water, hop on the bike and do the test.
I will use that Ramp Test FTP and that KG to calculate my w/kg
If it were me I would weigh myself on the morning of the test and then calculate w/kg from that. But ultimately a lb here or there is going to make little difference to your w/kg from an FTP test. You’d need to be looking at more significant swings in weight to see a significant fluctuation in w/kg.
For example, at my weight of 142lb if I add 3lb to my weight it’s roughly a .1 decrease in w/kg. And if you are taller/larger then the difference will be less as the change in weight will be proportionally smaller.
The more important data will be the trend in w/kg over time rather than on a given day.
As others say just go with your weight that day. Small fluctuations are unlikely to make a huge difference. It’s good for monitoring trends but in the grand scheme of things a standalone ratio doesn’t have a major impact on anything.
My personal method is to use a round kg. I only change my kg in TR if its been closer to a different kg for a few days. So for example I float around 69kg, some days I’ll measure as low as 68.1kg but I wont drop the kg in TR unless its consistently closer to 68kg.
I just use my most recent weigh in weight. It’s only indicative. Weight does fluctuate (hydrating/ food etc), and then what you are (or aren’t) wearing for weighing in. As soon as you eat or drink, your weight will change. The trend is your friend…
I update my weight every Monday morning but weigh myself daily. In general you should be using a much longer term average when tracking weight. You want to see a monthly average not a daily average.
Amazing to me that people don’t see large fluctuations in weight - in the past 7 days I have weighed the following: 165, 167.8, 168.2, 166, 164, 164, 165
4.2 pounds +/- within a week feels huge to me! My weekly average is always like this based primarily on salt intake but also digestive weight. The better target is the month over month average which (hopefully) shows an overall downward trend
I also see big fluctuations daily. This week the range has been 3 lbs and thats regular.
Whatever my weight actually is minus about 10kg so I can say I have a big time w/kg. 
This is why I love trendweight
Makes the daily variation much easier to see past when you’re trying to lose weight!
I try to do something similar with the app that connects to my scale - I look at the daily numbers but really only care about the month over month trend.
Have everything I intend wearing, trainers and all, just before I jump on the bike I weigh myself… to me that gives an accurate w/kg because if I was riding outdoors, that is what it would really be.
I do it this way as that is what you should be doing for Zwift races/events, amazes me how many people manage to stay the same weight for months at a time;)
good to hear this - as i fluctuate up to 2kg sometimes as well.
after a rest day my gain is huge… even this week i have gone from 60.3kg - 58.6kg.
i do the same - take a weekly / 4 week and 6 week snapshot … which is what i think i will use to inform my FTP .
thanks for your input.