Weight Loss Calculator

Daily Calorie Target

{{ format(dailyCalories) }} kcal

BMR {{ format(bmr) }} TDEE {{ format(tdee) }} {{ format(deficit) }} kcal/day deficit {{ format(Math.abs(deficit)) }} kcal/day surplus

{{ warnings.length }} warning{{ warnings.length>1?'s':'' }}

{{ w }}

Age:

Sex:

Height (cm):

Current Weight:

Goal Weight:

Timeframe:

Activity Level:

Energy per kg:

kcal/kg

Calorie floor policy:

Custom floor:

kcal/day

Metric	Value	Copy
BMR (kcal/day)	{{ format(bmr) }}
TDEE (kcal/day)	{{ format(tdee) }}
{{ deficit>=0 ? 'Deficit' : 'Surplus' }} (kcal/day)	{{ format(Math.abs(deficit)) }}
Daily Calorie Target	{{ format(dailyCalories) }} kcal
Timeframe (weeks)	{{ formatDec(weeksValue) }}
Weekly {{ weeklyLoss>=0 ? 'Loss' : 'Gain' }} ({{ weightUnit }})	{{ formatDec(Math.abs(weeklyLoss)) }}
Total {{ totalLoss>=0 ? 'Loss' : 'Gain' }} ({{ weightUnit }})	{{ formatDec(Math.abs(totalLoss)) }}
Applied Calorie Floor	{{ format(calorieFloorApplied) }} kcal/day

Week	Weight ({{ weightUnit }})	Change-to-date	TDEE	Cal Target	Copy
{{ r.week }}	{{ formatDec(r.weight) }}	{{ formatDec(r.change) }}	{{ format(r.tdee) }}	{{ format(r.cal) }}
No schedule generated.

Tags: Body Metrics , Nutrition

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Calorie targets are a practical way to plan weight change while keeping pace reasonable and consistent. A daily calorie calculator for weight loss helps you choose an intake that matches your size, age, and weekly activity so progress feels steady.

Results show an estimated resting need, a daily use based on activity, and a daily target that creates the requested pace. You provide age, sex, height, current and goal weight, a timeframe in weeks or months, and an activity pattern, then review the weekly plan.

For example, moving from 80 kg to 70 kg in 12 weeks with moderate activity yields about 1 800 kcal per day, along with a week by week weight path and a comparison to daily use. The numbers help you check effort and timing before you start.

Short timelines can imply fast weekly change, so consider comfort and sustainability. Enter consistent units and revisit the plan as your weight shifts to keep expectations aligned. This tool provides informational estimates and does not substitute professional advice.

Technical Details:

The quantities considered are resting energy use and daily energy use from routine activity. The first is an estimate of Basal Metabolic Rate (BMR). The second, Total Daily Energy Expenditure (TDEE), scales that estimate by an activity factor to approximate typical days.

The daily calorie target is computed by subtracting a planned energy gap from TDEE. The planned gap corresponds to a weekly weight change multiplied by an energy per kilogram constant, spread across seven days. A minimum calorie floor may limit the target for safety.

Results are interpreted as follows: BMR describes baseline needs at rest, TDEE reflects average use on active days, and the daily target is a practical intake for the requested pace. When weekly change is large, comfort and adherence usually drop, so a longer timeframe often helps.

Comparability depends on using the same units and activity description between checks. Months are converted to weeks using 4.345, and weights in pounds are converted to kilograms using 0.45359237 to maintain consistent computation.

\begin{array}{lll} BMR & = & 10 \times W + 6.25 \times H - 5 \times A + S \\ TDEE & = & BMR \times AF \\ Δ w & = & \frac{w_{0} - w_{g}}{weeks} \\ d & = & \frac{| Δ w | \times k_{e}}{7} \\ C & = & TDEE - d \\ C^{'} & = & \max (C, floor) \end{array}

Symbols and units used in the computation
Symbol	Meaning	Unit/Datatype	Source
W	Body mass	kg	Input (kg or converted from lb)
H	Height	cm	Input
A	Age	years	Input
S	Sex offset	+5 male, −161 female	Constant from formula
AF	Activity factor	1.2 to 1.9	Input (discrete options)
$∆ w$	Weekly weight change	kg wk⁻¹ or lb wk⁻¹	Derived
$k_{e}$	Energy per kg	kcal kg⁻¹	Input (default 7700)
d	Daily energy gap	kcal day⁻¹	Derived
C	Daily calorie target	kcal day⁻¹	Derived
floor	Minimum allowed target	kcal day⁻¹	Policy (none, safe, custom)

Worked Example

Inputs: age 30, male, height 175 cm, weight 80 kg, goal 70 kg, timeframe 12 weeks, activity moderate (AF = 1.55), energy per kg 7700.

\begin{array}{l} BMR & = & 10 \times 80 + 6.25 \times 175 - 5 \times 30 + 5 = 1748.75 \\ TDEE & = & 1748.75 \times 1.55 = 2710.56 \\ ∆ w & = & \frac{10}{12} = 0.8333 \\ d & = & \frac{0.8333 \times 7700}{7} = 916.67 \\ C & = & 2710.56 - 916.67 = 1793.89 \end{array}

Displayed values round to whole numbers for BMR, TDEE, and daily calories, and one decimal for weekly change. Interpretation: a target near 1 800 kcal/day fits the chosen pace.

Typical weekly change thresholds
Threshold Band	Lower Bound	Upper Bound	Interpretation	Action Cue
Within guidance (kg)	0.0	1.0	Common steady range	Proceed and monitor comfort
Above guidance (kg)	1.0	∞	Often aggressive	Consider a longer timeframe
Within guidance (lb)	0.0	2.0	Common steady range	Proceed and monitor comfort
Above guidance (lb)	2.0	∞	Often aggressive	Consider a longer timeframe

Units, Precision & Rounding

Numbers display with the current locale’s decimal separator.
BMR, TDEE, and daily calories round to the nearest whole kcal.
Weekly weight values display to one decimal place.
Months convert to weeks using 4.345; schedule length rounds to the nearest whole week.

Validation & Bounds

Input validation and bounds
Field	Type	Min	Max	Step/Pattern	Error/Warning Text
Age	number	0	—	—	—
Sex	select	—	—	male, female	—
Height (cm)	number	0	—	—	Enter a positive height.
Weight	number	0	—	—	Enter a positive current weight.
Goal Weight	number	0	—	—	Goal above current shows a surplus plan.
Weight Unit	select	—	—	kg, lb	—
Timeframe	number	1	—	weeks or months	Timeframe must be at least 1.
Activity	select	—	—	sedentary, light, moderate, active, extra	—
Energy per kg	number	1000	—	step 10	—
Calorie Floor Policy	select	—	—	none, safe, custom	Calorie floor applied.
Custom Floor	number	0	—	step 10	—

I/O Formats

Inputs and outputs overview
Input	Accepted Families	Output	Encoding/Precision	Rounding
Age, sex, height, weights, timeframe, activity	Numeric and categorical	BMR, TDEE, deficit/surplus, daily target	kcal, kg/lb, weeks	Integers or 1 decimal
Advanced policies	Energy per kg, calorie floor	Weekly schedule	Table and charts	Integers for kcal, 1 decimal for weight
Export	—	Metrics CSV, schedule CSV, plan JSON	Text files	As displayed

Networking & Storage

All calculations run in the browser; no remote data requests are made.
Downloads and copy actions create local text blobs and clipboard entries only.
Charts are rendered by a lightweight charting layer if available.

Performance & Complexity

Computation is O(n) in the number of weeks for schedule generation.
Chart rendering scales linearly with data points.

Diagnostics & Determinism

Identical inputs yield identical outputs.
Warnings summarize boundary conditions and aggressive pacing.

Security & Privacy

Inputs are handled locally, outputs are generated locally, and no secrets or keys are used. No data is transmitted or stored server‑side.

Assumptions & Limitations

Resting needs follow the Mifflin–St Jeor form with sex offsets.
Activity is represented by fixed multipliers and does not vary day to day.
Energy per kilogram is constant; body composition shifts are not modeled.
Months convert to weeks using 4.345 for scheduling.
Schedule length rounds to the nearest whole week; daily target remains constant across weeks.
Warnings are advisory and do not block calculation.
Weight unit selection is shared by current and goal entries.
Charts require a charting layer; absence affects visuals only.

Edge Cases & Error Sources

Zero or negative height or weight produces warnings and unrealistic results.
Timeframe below four weeks triggers aggressive‑pace warnings.
Goal above current weight flips to a surplus plan.
Very high energy per kg inflates the daily gap and may clamp at the floor.
Rounding may cause small differences between displayed and internal values.
Locale formatting can change thousands and decimal separators.
Clipboard permissions may block copy actions in some contexts.
Charts may not draw if the charting layer is unavailable.
Schedule length rounding can differ slightly from the exact weeks entered.
Using pounds changes the weekly guidance threshold to 2.0 lb per week.

Scientific Backing

BMR is computed with the Mifflin–St Jeor equation. TDEE uses activity multipliers applied to BMR. Weight change pacing converts mass change targets to energy using a per‑kilogram constant.

Privacy & Compliance

No protected health information is collected. All processing is browser‑based; downloads and copies remain on the device.

Step‑by‑Step Guide:

Calorie targets for planned weight change are computed from your measurements and desired pace.

Enter age, sex, and height.
Enter current and goal weight and pick the unit.
Choose a timeframe in weeks or months.
Select your activity level to scale daily use.
Open Advanced to set energy per kg or a calorie floor if needed.
Review the daily target, weekly schedule, and any warnings.

Example: 80 kg to 70 kg in 12 weeks at moderate activity gives a target near 1 800 kcal/day and a weekly drop near 0.8 kg.

If the plan feels aggressive, extend the timeframe.

You now have a clear daily target and a week by week path.

FAQ:

Is my data stored?

No. Calculations, copies, and downloads happen on your device. Nothing is sent to a server.

Local processing only.

How accurate is the estimate?

It uses a standard resting estimate and fixed activity multipliers. Individual needs vary, so treat results as planning targets, not measurements.

Refine with periodic check‑ins.

Which units can I use?

Height is in centimetres. Weight entries can be kilograms or pounds and must share the same unit.

Unit consistency matters.

What is the calorie floor?

It is a minimum daily target. Safe‑by‑sex sets 1200 for female and 1500 for male, and a custom option lets you choose another minimum.

A floor may reduce the planned pace.

How is TDEE calculated?

TDEE is BMR multiplied by the selected activity factor. The schedule updates TDEE weekly as projected weight changes.

Activity factor is constant between weeks.

Can I use it without a connection?

Yes. Once loaded, calculations work without a connection. Charts may require the page’s visual layer to be available.

No remote requests are made.

What do warnings mean?

They flag short timeframes, fast weekly change, non‑positive inputs, surplus plans, or when a calorie floor clamps the target.

Use them to reassess pace and inputs.

Is there any cost or license?

No payment is required for calculation and planning. Use is intended for personal planning and education.

Not financial or medical advice.

Troubleshooting:

No results showing: ensure height, weight, and timeframe are positive.
Target seems very low: a calorie floor may be applied by policy.
Fast weekly change warning: lengthen the timeframe or reduce the gap.
Charts missing: the page’s charting layer may not be available.
Copy fails: allow clipboard access or use the download options.
Numbers look odd: check unit selection and locale separators.

If daily calories display as zero, one or more inputs are invalid or the computed value is non‑positive; correct inputs to proceed.

Advanced Tips:

Tip Recalculate weekly as your weight changes to keep targets aligned.
Tip Use the same activity level each time to compare plans fairly.
Tip Adjust energy per kg if advised by a professional to match context.
Tip Extend timelines to reduce the risk of overly aggressive pacing.
Tip Keep height and age updated annually for small accuracy gains.
Tip Compare the schedule’s TDEE line to the target to visualize the gap.

Glossary:

BMR: Basal Metabolic Rate, resting energy use estimate.
TDEE: Total Daily Energy Expenditure, activity‑scaled use.
Activity factor (AF): Multiplier from 1.2 to 1.9 describing weekly activity.
Energy per kg: Constant in kcal per kilogram of weight change.
Calorie floor: Minimum allowed daily target for safety.
Weekly change: Planned mass change per week.