Weight Converter Calculator

Powerful, accurate weight converter with mass↔force toggle, kg↔lb quick box, lb+oz mixed parsing, niche units for jewelry and international trade, ingredient density conversions, DIM weight for shipping, batch processing with CSV/JSON export, precision and rounding presets, locale-aware inputs, accessible design, and shareable permalinks. PWA offline-ready, embeddable widget, developer-friendly API, themes.

Mass Force

Mass uses SI kilograms/grams. Force uses Newtons, lbf, kgf (with standard gravity g₀ = 9.80665 m/s²).

Quick Convert

Rounding:

Decimals: 4

Significant figures

Scientific notation

Input

Mixed input supported: 2 lb 3 oz, 1 st 8 lb, 2lbs3oz. Locale digits (e.g., ١٢٣٤) accepted.

From unit

Output

To unit

More units (editable grid)

Type into any box below; everything updates instantly.

Ingredient

Assumed at ~20 °C; densities are approximate. Override below.

Density

g/mL

Amount

From

Result

Amount

From

Karat purity

24K is 99.99% pure; 18K ≈ 75%.

Result

Also shows pure metal mass based on karat.

Length

Width

Height

Units

DIM factor

DIM weight

Compare to actual weight; carriers bill on the higher of the two.

System

Bar weight

45 lb or 20 kg typical.

Target total

Related: BMI · 1RM

Paste lines (value + unit). Examples:

Parser accepts mixed inputs and locale digits.

Output columns

Prefill via query string:

?value=2.5&from=kg&to=lb
?value=2+lb+3+oz&from=mixed&to=kg
?mode=force&value=10&from=N&to=lbf
?format=json&value=5&from=kg&to=lb

When format=json is present, the page renders a JSON payload below (no headers change).

Embed widget (iframe):

How it works (factor–label method)

We convert all mass units to the SI base (kilograms) internally, or to Newtons for force. Mixed inputs like 1 st 8 lb are parsed and normalized.

Mass base: 1 lb = 0.45359237 kg, 1 oz (av) = 28.349523125 g, 1 ozt = 31.1034768 g.
Force base: g₀ = 9.80665 m/s²; 1 lbf = 4.4482216152605 N; 1 kgf = 9.80665 N.
Regional units: catty (jin) shown as 500 g; picul (HK) as 60.478982 kg; tael (HK) as 37.799365 g.

Accuracy note: unit factors follow SI/NIST-style definitions; last reviewed . Report issues via your site’s contact form.

How this calculator works

This tool converts between mass and force units using the factor–label method. Every value normalizes to a base unit, then translates to the requested target, preserving precision and your chosen rounding behavior. For mass we normalize to kilograms; for force we normalize to newtons, using standard gravity g₀ = 9.80665 m/s².

Mass conversions at a glance

Pair	Formula	Exact factor
lb → kg	kg = lb × 0.45359237	0.45359237
kg → lb	lb = kg ÷ 0.45359237	1 ÷ 0.45359237
oz (av) → g	g = oz × 28.349523125	28.349523125
stone → kg	kg = st × 6.35029318	6.35029318
ozt → g	g = ozt × 31.1034768	31.1034768

Pair

Formula

Exact factor

lb → kg

kg = lb × 0.45359237

0.45359237

kg → lb

lb = kg ÷ 0.45359237

1 ÷ 0.45359237

oz (av) → g

g = oz × 28.349523125

28.349523125

stone → kg

kg = st × 6.35029318

6.35029318

ozt → g

g = ozt × 31.1034768

31.1034768

Mixed inputs like “2 lb 3 oz” or “1 st 8 lb” are parsed by splitting the components and converting each piece to kilograms before summing. Locale digits and decimal comma are supported; the parser also ignores thousands separators gracefully, so “1,200 g” just works.

Force conversions and mass–force toggle

When you switch to force, values convert through newtons. Pound‑force and kilogram‑force reflect the force exerted by a pound or kilogram of mass at standard gravity. The relationship among units is consistent and reversible, which makes comparisons straightforward for engineering, lifting, and equipment specifications.

Pair	Formula	Exact factor
N → lbf	lbf = N ÷ 4.4482216152605	4.4482216152605
N → kgf	kgf = N ÷ 9.80665	9.80665
lbf → N	N = lbf × 4.4482216152605	4.4482216152605
kgf → N	N = kgf × 9.80665	9.80665

Pair

Formula

Exact factor

N → lbf

lbf = N ÷ 4.4482216152605

4.4482216152605

N → kgf

kgf = N ÷ 9.80665

9.80665

lbf → N

N = lbf × 4.4482216152605

4.4482216152605

kgf → N

N = kgf × 9.80665

9.80665

Precision, rounding, and significant figures

The decimals slider controls display precision, while the significant‑figures option rounds values to a chosen number of meaningful digits. Rounding presets apply sensible increments to specific targets: cooking snaps ounces to eighths, shipping snaps kilograms to tenths, and jewelry snaps grams or carats to hundredths. These presets never change internal math, only the presented output.

Preset	Target	Increment
Cooking	oz	⅛ oz
Shipping	kg	0.1 kg
Jewelry	g, ct	0.01

Preset

Target

Increment

Cooking

⅛ oz

Shipping

0.1 kg

Jewelry

g, ct

0.01

Ingredient, jewelry, DIM, and batch tools

Ingredient mode converts weight ↔ volume using density in g/mL, with presets for common items. Jewelry mode supports troy ounces, pennyweight, grains, and karat purity; it also reports pure metal mass. DIM weight computes billable weight from box dimensions and carrier factors in inches or centimeters. Batch mode processes pasted lines or CSV, builds totals, and exports CSV or JSON.

For reliability and transparency, the calculator includes copy buttons, shareable permalinks, and accessibility tags. All constants align with international definitions. If your workflow requires custom units or additional densities, use the batch converter or send suggestions; the internal model is easily extended while keeping performance fast and the interface familiar.

The advanced grid lets you edit any unit directly; typing in grains updates grams, kilograms, stones, and tons in real time. Mobile users get large tap targets and numeric keypads; desktop users can tab swiftly through fields. Developers can prefill inputs via query parameters or embed the widget inside documentation, dashboards, learning portals, or storefront product pages.

Print styles ensure clean, branded, exportable summaries.