A TDEE calculator for cutting and bulking gives you one number, your estimated maintenance calories, and you build both plans from it: eat below it to cut, above it to bulk. The calculator is the same either way. What changes is how your real TDEE behaves once you start. On a cut it tends to fall, sometimes by more than the weight you've lost would explain. On a bulk it tends to rise. So the calculator's number is a first guess. You check it against two to three weeks of logged food and weight, then re-check it as your weight moves.
Last updated: October 2026
What's actually inside the number
TDEE stands for total daily energy expenditure, the calories you burn in a full day. Calculators present it as one figure, but it's four parts added together:
| Part | What it is | Rough share of TDEE |
|---|---|---|
| Resting burn (BMR) | Keeping you alive at rest: breathing, circulation, organs | About 60 to 70 percent |
| Thermic effect of food | Energy spent digesting what you eat | About 10 percent |
| Exercise | Planned training: lifting, runs, classes | Varies widely |
| NEAT | Non-exercise activity: walking, standing, fidgeting, chores | Varies widely |
Most calculators estimate the resting part with the Mifflin-St Jeor equation, then multiply by an activity factor to cover the other three. That single multiplier is doing a lot of guessing. The Calorie Deficit Calculator for Fat Loss post walks through the formula and why the activity setting swings the answer so much, so I won't repeat it here.
The part worth noticing is that three of those four pieces move when you change how much you eat.
Why the same TDEE behaves differently on a cut and a bulk
Everyone knows a cut means eating less and a bulk means eating more. Fewer people realize their maintenance number won't sit still while they do it.
On a cut, several parts shrink at once. A smaller body needs less energy at rest. Less food means a smaller thermic effect. And NEAT often drops without you noticing: fewer steps, less fidgeting, more sitting. Researchers call the overall slowdown adaptive thermogenesis, and it's why a deficit that worked in week two can look like maintenance by week ten. If a cut has stalled on you before, that wasn't a willpower problem. You probably suspected the number had stopped working, and you were right: the target moved under you.
On a bulk, the same parts grow. More body mass costs more to maintain, more food takes more energy to digest, and some people move more when they're eating more (how much varies a lot from person to person). So a surplus that started at a few hundred calories shrinks in real terms as you gain.
Protein shifts the picture a little. Your body spends roughly 20 to 30 percent of protein's calories digesting it, compared with about 5 to 10 percent for carbs and 0 to 3 percent for fat. It won't make or break a plan, but a high-protein cut burns slightly more through digestion than the same calories from mostly carbs and fat.
The upshot: one TDEE estimate works fine for setting up either phase. It doesn't stay right for the whole phase.
The first week lies, in both directions
Here's the trap that catches people on day eight.
Start a cut and the scale often drops fast in the first week. Much of that is water and stored carbohydrate (glycogen), not fat. Start a bulk and the scale can jump by a few pounds for the same reason in reverse. Neither tells you much about your real TDEE.
So don't judge the calculator's number on week one. Give it two to three weeks, and compare weekly averages rather than single mornings.
How to find your real TDEE from your own log
This is the method I trust more than any calculator, because it uses your body instead of a population average.
- Pick a starting target from a calculator and eat close to it every day.
- Log everything for two to three weeks. Rough estimates are fine. Skipped days aren't.
- Weigh yourself several mornings a week, same conditions each time, and average each week.
- Compare the first and last weekly averages. If your weight held steady, your average daily intake over that stretch is a good estimate of your real maintenance.
- If your weight moved, adjust. A common rough conversion is about 500 calories a day for every pound per week of change. Losing a pound a week at 2,100 calories suggests maintenance near 2,600. Treat that as approximate, since water and the slowdown above both blur it.
Now you have a personal TDEE. Set your cut or bulk from that, not from the original calculator output. For sizing the gap, the Calorie Deficit Calculator for Fat Loss post covers deficits, and Macro Calculator for Muscle Gain covers surpluses and how to split them into protein, carbs and fat.
When to recalculate
My opinion: most people recalculate too often. Changing your target every Monday based on a noisy scale means you never learn what any number actually does.
I'd re-run the process at three points:
- When you switch phases, from cutting to bulking or back.
- When your weekly average has moved by around 5 percent of your body weight.
- When progress has stalled for three honest weeks of consistent logging.
When you switch from a cut to a bulk, keep in mind that your maintenance is probably lower than it was before the cut. Stepping calories up over a couple of weeks while you watch the trend is gentler than jumping straight to an old number.
Where AllStrong fits
AllStrong estimates your TDEE from your stats and activity level using the Mifflin-St Jeor equation with standard activity multipliers (1.2 for sedentary up to 1.9 for extremely active). When you sign up, it sets your starting calorie and macro targets from that estimate, and a progress bar fills in as you log through the day. The TDEE estimate and the targets are on the free plan.
It doesn't pick a cut or a bulk for you. The TDEE screen shows your maintenance next to a mild deficit (250 calories under), a moderate deficit (500 under) and a mild surplus (250 over), and you set the calorie target you want to eat to under Profile, then Nutrition Targets. That decision, and the size of the gap, is yours.
Once you have about two weeks of both weigh-ins and food logs, the TDEE screen also blends the formula with your real intake and weight trend, which is the five-step method above done for you. Weigh-ins synced from Health Connect on Android count. It doesn't change your target on its own, so when that number moves, update your calories yourself.
The logging side is what makes the five-step method above work. You can type or say what you ate, like "two eggs, toast and a banana," and AllStrong estimates calories and macros using USDA FoodData Central data. That's free. Barcode scanning and photo meal logging are Premium features, included free when your gym runs AllStrong. The Meal Tracking Apps That Use AI post covers those logging options in more detail.
Fair warning on all of this: TDEE formulas were built for average, healthy adults. If you're pregnant, under 18, managing a condition or medication that affects weight, or have a history of disordered eating, a doctor or registered dietitian should set your numbers. And the whole method depends on logging most days for a few weeks, which is a habit before it's a calculation. That's where a habit tracking app approach helps.
Frequently asked questions
Can I use the same TDEE calculator for cutting and bulking?
Yes. A TDEE calculator estimates your maintenance calories, and both plans start from that number: eat below it to cut, above it to bulk. The difference is what happens next. Your real TDEE tends to fall during a cut and rise during a bulk, so plan to re-check it against your logged intake and weight trend every few weeks.
How do I find my actual TDEE instead of an estimate?
Eat close to a set target and log your food for two to three weeks while weighing yourself several mornings a week. If your weekly average weight stays flat, your average daily intake is roughly your maintenance. If it moves, adjust by about 500 calories a day per pound per week of change, and treat the result as approximate.
How often should I recalculate my TDEE?
Less often than most people do. Recalculate when you switch between cutting and bulking, when your average weight has changed by around 5 percent, or when progress has stalled for three weeks of consistent logging. Changing targets every week on a noisy scale makes it hard to tell what any number is actually doing.
Why did my weight jump in the first week of a bulk?
Mostly water and stored carbohydrate, called glycogen. Eating more refills glycogen, which holds water, so the scale can rise by a few pounds quickly. The reverse happens at the start of a cut. Neither reflects fat or muscle change, so wait two to three weeks and compare weekly averages before deciding whether your TDEE estimate was right.