RMR vs. BMR and how to calculate TDEE


55+ Old school lifter
I really need to drop my BF%, so I'm looking at first getting my diet in check. Today I had a BodPod test, BF% is 21%, I want to get into the low teens eventually but I'm 56 so I'll take what I can get!
I also had Resting Metabolic Rate tested at 1950 cal.

However, to calculate TDEE, all the online calculators use BMR not RMR that I was measured for. So ... is TDEE calculated off RMR or BMR and is there a preference?

I strongly suspect that RMR and BMR are interchangeable.

That said, I personally have doubts about the usefulness of the concept - I don't think that TDEE can be established with sufficient accuracy to guide nutrition for weight loss, there are just too many variables. Hormonal milieu exerts a stronger influence than caloric balance.

(I'm a 55 y/o old school lifter too, about to turn 56!)
Well, RMR was tested at 1950cals and the tester said that’s what you burn to exist in a day , don’t go lower. But if I use any online calculator, figure in TDEE and drop it by 20% for a cut, I come in lower?

I’ve been winging it for the past 6 months and gone from 200 to 180, 29% BF to 21% BF so I must be doing something right. No gear, and I do look better I’ll take it!
I'm just a apprentice in diet and the ins and outs but after reading 3Js thread and seeing the system of BMR/TDEE and adjusting it the main point I got was establishing a decent start point based off some measured and mathematically established point and adjusting from there.

If your body weight is steady decrease calories by a couple hundred a day and run it out for a while.

I can build rituals around things. My weight ins are always in the morning after 1 or 2 cups of coffee, morning poo and no food. If I dont poo in time and have drank more coffee or ate for some reason I wont step on the scale. If I feel like I might have to take a leak I try.

My only diet knowledge would come from eating issues with epilepsy medications. Over the last 3 years I dropped from like 157lb down tob135lbs, up tob173lbs starting TRT and lifting, back down to the 150s and I'm now sitting at 168 lbs.

I think a true number iabsimikiar to an equilibrium price in business or economics. It's a thing and a point but the variables male ot impossible to calculate a precise price and calories per person can be the same thing and it fluctuates daily.
To calculate your Total Day Energy Expenditure (TDEE), it’s common to use your Basal Metabolic Rate (BMR) as a starting point. BMR represents the calories your body needs at complete rest. However, Resting Metabolic Rate (RMR) is also a valid measure and provides a similar estimate to BMR. You can use your RMR value to calculate your TDEE by applying an activity multiplier based on your activity level. While there isn’t a strict preference between using RMR or BMR, using RMR in conjunction with an appropriate activity multiplier can give you a good estimate of your TDEE. Good luck with your goal of reducing your body fat percentage.