Sleeping burns about 0.85–1.05 kcal per kg per hour; an 80 kg person uses roughly 540–670 calories across 8 hours.
Low Rate
Typical Rate
Upper Range
Short Sleep
- 6 hours in bed
- 70 kg → ~430 kcal
- Keep wake-ups minimal
Time: 6h
Typical Night
- 7–8 hours
- 70 kg → ~505–580 kcal
- Consistent schedule helps
Time: 7–8h
Long Sleep
- 9 hours+
- 70 kg → ~650+ kcal
- Focus on quality, not just time
Time: 9h+
Why Sleep Burns Calories At All
Your body never clocks out. While you’re out cold, cells still build and repair tissue, your brain tidies synapses, and your heart and lungs keep tempo. That baseline work takes energy. Most of the overnight burn comes from resting metabolic rate (RMR)—the calories your body uses at rest to run core systems. Researchers estimate sleep intensity close to rest, a touch under quiet sitting, which is why calculators peg the rate around 0.95 kcal per kilogram per hour.
Calories Burned While Asleep — Calculation Steps
The cleanest way to estimate your number is a three-part multiplication: your weight in kilograms × per-hour rate × hours asleep. The per-hour rate comes from MET values—a standard that sets “rest” at ~1.0 MET (≈1 kcal/kg/h) and assigns sleep just under that. If you don’t know your kilograms, divide pounds by 2.2. Then pick a sensible rate within the 0.85–1.05 band based on your night (deep, calm sleep near the low end; restless nights near the high end).
Broad Reference Table: Eight-Hour Sleep Burn By Body Weight
Use this to ballpark an 8-hour night using the typical 0.95 kcal/kg/h rate. Adjust up or down if your sleep runs cooler/calmer or more restless.
| Body Weight | 8-Hour Sleep Burn | Per Hour (kcal) |
|---|---|---|
| 50 kg (110 lb) | ~380 kcal | ~47 |
| 60 kg (132 lb) | ~456 kcal | ~57 |
| 70 kg (154 lb) | ~532 kcal | ~66 |
| 80 kg (176 lb) | ~608 kcal | ~76 |
| 90 kg (198 lb) | ~684 kcal | ~85 |
| 100 kg (220 lb) | ~760 kcal | ~95 |
| 110 kg (243 lb) | ~836 kcal | ~104 |
| 120 kg (265 lb) | ~912 kcal | ~114 |
These numbers reflect a standard MET approach used in exercise science. One MET equals about 1 kcal/kg/h, and sleep sits a notch lower, which lines up with lab methods that measure resting burn from oxygen use. If you want the full background on how METs are defined, see the Compendium MET definition.
Pick The Right Rate For Your Night
Calorie rate during sleep shifts with real-world details. Cooler rooms and deep sleep stages nudge the rate down. Warmer rooms, frequent awakenings, and late meals push it up a bit. Muscle mass matters because it raises resting burn across the day. Illness and fever can lift resting burn as well. Aim for 0.95 as a default, then slide a little lower or higher based on how the night actually felt.
Where Weight, Height, Age, And Sex Fit
If you want a tighter estimate than the quick table, plug your stats into a resting energy equation, then apply a “sleep fraction.” A widely used pick in nutrition research is the Mifflin-St Jeor formula for resting energy. It uses weight, height, age, and sex to estimate daily resting calories. After you have that daily number, divide by 24 to get an hourly baseline and trim a small amount to represent sleep being just under quiet rest. That lands you very close to the 0.85–1.05 range.
Worked Example (Step-By-Step)
- Convert weight: 176 lb ÷ 2.2 = 80 kg.
- Choose rate: typical night → 0.95 kcal/kg/h.
- Multiply: 80 × 0.95 × 8 hours = 608 kcal.
Have a calmer night in a cool room? Use 0.90 and you’d see ~576 kcal. Restless? Use 1.00 and you’d see ~640 kcal.
How Sleep Length Changes The Total
The hourly rate is steady; total burn scales with time. A 70 kg person using 0.95 kcal/kg/h spends about 66 kcal per hour asleep. Six hours comes out near 400 kcal; nine hours lands near 600+ kcal. Quality still matters. Broken sleep can bump rate slightly but leaves you groggy and hungry the next day—no trade-off worth chasing.
Sleep, Health, And A Simple Reality Check
A solid night supports appetite control, glucose handling, and exercise follow-through. Adults should aim for at least 7 hours nightly, per the CDC adult sleep basics. You won’t “lose weight by sleeping,” but better sleep makes weight control easier by taming cravings and stabilizing energy across the day.
When A Calculator Isn’t Enough
Equations estimate. They don’t know your lean mass, hormones, or nighttime awakenings. If your numbers never match progress over weeks, the intake side is usually the culprit—snacks, drinks, portions, and tracking drift. Tighten inputs, then revisit outputs.
How This Ties Into Your Day
Sleep burn is just one slice of a day’s total. The rest comes from daily movement and the cost of digesting food. If you want a sense of your baseline outside of workouts, read up on calories burned while resting. That context helps you keep expectations grounded once the alarm rings.
Fine-Tuning Your Estimate Without Gadgets
Wearables try to infer energy use from heart rate and motion. During sleep, motion is minimal and heart signals drift with stress, meals, caffeine, and room temperature. You can get just as close with the simple rate range—then calibrate against scale trends and waist measurements over 2–4 weeks. If weight holds steady, your intake roughly matches your true burn. Adjust food intake by 200–300 kcal steps to change course.
Conditions That Nudge Nightly Burn
Use the table as a guide. These are modest swings—not license to count sleep as a “fat-burn workout.”
| Factor | Adjustment | Why It Moves |
|---|---|---|
| Cool Room (17–19 °C) | − to slightly − | Deeper sleep; less tossing |
| Warm Room (>23 °C) | + small | More awakenings; thermoregulation |
| Late Heavy Meal | + small | Digestive costs during early night |
| Fever/Illness | + moderate | Immune response lifts resting burn |
| Higher Muscle Mass | + ongoing | More metabolically active tissue |
| Sedatives/Alcohol | − to mixed | Lighter REM, more fragmentation |
FAQ-Style Clarity Without The FAQ Section
Do Taller Or Older People Burn The Same?
Height and age shift resting burn through lean mass and organ size. That’s why equations that include weight, height, age, and sex tend to predict better than a one-size-fits-all chart. If you want clinical-style math, many dietitians still lean on Mifflin-St Jeor as the starting point before activity multipliers are layered in.
Can Cold Rooms “Boost” Sleep Calories?
Chilly air can raise brown-fat activity and shivering costs, but chasing extra calorie burn at night trades comfort and recovery for peanuts. Go for stable sleep first. If the goal is more daily burn, do it while awake with steps and resistance work.
What About Naps?
Same math. A 30-minute nap for a 70 kg person near 0.95 kcal/kg/h costs roughly 33 kcal. Naps help alertness; they don’t move weight by themselves.
Build Your Own Nightly Estimate (Template)
Step 1 — Weigh-In
Convert pounds to kilograms (lb ÷ 2.2). Jot the number.
Step 2 — Pick A Rate
Use 0.95 as your default. Slide to 0.90 for calm, cool nights or to 1.00–1.05 for restless nights.
Step 3 — Multiply
Weight (kg) × rate (kcal/kg/h) × hours asleep. Round to the nearest 10 kcal. Revisit weekly if your routine or room changes.
Smart Links For Deeper Reading
Want a broader picture of passive burn across the day? Try our daily burn at rest walkthrough.
Method notes: The nightly rate range reflects standard MET convention (sleep near 0.95 of 1 kcal/kg/h) and is consistent with research that estimates resting energy using weight-, height-, age-, and sex-based equations such as Mifflin-St Jeor. Sleep duration guidance follows CDC recommendations for adults (7+ hours).