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Health & Fitness

Weight Loss Percentage Calculator

Percentage of body weight lost, total change and average weekly pace, with the 5% and 10% clinical milestones.

Your inputs

Change any value, everything updates instantly.

Allowed range 20–400 kg.

Allowed range 20–400 kg.

Allowed range 1–104 wk.

Try an example

Body weight lost

12.51 %

This means your body weight lost works out to 12.51 % with the values you entered.

Body weight lost: 12.51 %Total change: 12.2 kgAverage weekly pace: 1.02 kg/wk
Body weight lostTotal changeAverage weekly pace
12.51 %

What you are seeing

Each bar grows to show one result for your everyday situation.

The top bar is the main answer: 12.51 %.

Change starting weight (now 97.5) and every bar updates instantly.

Total change

12.2 kg

Worked out from your inputs using the formula below.

Average weekly pace

1.02 kg/wk

Worked out from your inputs using the formula below.

Result explanation: Body weight lost

12.51 %.

Real-life comparison: With starting weight 10% higher, it would be 20.47 %.

Low, normal or high? Past the 10% milestone.

Graph and details

20115210305400-326-12479Starting weight%

How the answer changes with starting weight

How to read this chart: The line shows the main result across the allowed range. The dot marks your input.

What this calculator does

Percentage of body weight lost, total change and average weekly pace, with the 5% and 10% clinical milestones.

What your result means

This means your body weight lost works out to 12.51 % with the values you entered.

Real-life numbers vary, prices, habits and conditions change, so treat this as a practical guide.

Results are shown rounded; the full value is used internally.

The formulas

The same formula runs every time you change an input.

1. Weight Loss Percentage

lost = start − current; % lost = lost ÷ start × 100; weekly pace = lost ÷ weeks

Symbols

start
Starting weight (kg)
current
Current weight (kg)
weeks
Weeks elapsed (wk)

Why this formula works

This is the standard everyday arithmetic for this situation, using the values you enter.

Unit check

Inputs are converted to consistent units before calculating ✓

Worked example

  1. Substitute your values: Starting weight = 97.5; Current weight = 85.3; Weeks elapsed = 12
  2. Apply the formula: lost = start − current; % lost = lost ÷ start × 100; weekly pace = lost ÷ weeks = 12.51

Common mistakes

  • Entering a value in the wrong unit (for example minutes instead of hours).
  • Using an outdated price or rate.
  • Forgetting extra costs or time that apply in your case.

Working for your numbers

  1. Substitute your values: Starting weight = 97.5; Current weight = 85.3; Weeks elapsed = 12
  2. Apply the formula: lost = start − current; % lost = lost ÷ start × 100; weekly pace = lost ÷ weeks = 12.51

This means your body weight lost works out to 12.51 % with the values you entered.

Frequently asked questions

What does this weight loss percentage calculator calculate?

Percentage of body weight lost, total change and average weekly pace, with the 5% and 10% clinical milestones.

How accurate is the result?

The calculation follows the stated formula exactly. Your result is an estimate and depends on the accuracy of the values you enter.

Can I use different units or currencies?

Yes. Use the controls beside the calculator inputs. Conversions preserve the underlying value used by the formula.

Symbols and assumptions

start
Starting weight (kg)
current
Current weight (kg)
weeks
Weeks elapsed (wk)
  • Values entered are realistic for your situation.
  • Rates and prices stay constant over the period calculated.
  • Displayed values are rounded; internal values are not.

Sources and review

Reviewed 2026-09-25 · Next review 2027-09-25

Time and Frequency DivisionNISTHandbook 44 — specifications for weighing and measuring devicesNIST

Important limitation. Practical estimate for everyday planning. Real outcomes depend on prices, conditions and personal circumstances, check important figures before relying on them.

Quick reference

Weight Loss Percentage Calculator: results for common inputs, worked out with the formula on this page.
ScenarioStarting weight (kg)Current weight (kg)Weeks elapsed (wk)Body weight lost
Worked example97.585.31212.5128 %
Half the amounts48.842.6612.7049 %
Double the amounts195170.62412.5128 %

Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.

Reviewed 2026-10-18 · Next review 2027-04-18

Report a mistake or request an improvement

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