Stones to KG Converter — Convert Stones to Kilograms (Exact: kg = st × 6.35029318)
Professional stones (st) to kilograms (kg) converter using the exact relation 1 stone = 14 lb = 6.35029318 kg. Great for UK/IE body weight, sports weigh-ins, nutrition tracking, and mixed-unit reporting.
Exact factors: 1 st = 14 lb = 6.35029318 kg ⇒ kg = st × 6.35029318. Explore more mass tools at our free weight conversion calculator.
About Stones to Kilograms Conversion
The stone (st) remains a culturally preferred unit for personal body weight in the UK and Ireland. The kilogram (kg) is the global SI base unit for mass and the standard in medical records, nutrition science, manufacturing, and research. Converting stones to kilograms makes your data portable across systems, publications, and audiences. If your product or report speaks to both UK/IE consumers and international stakeholders, present stones for readability while ensuring an exact kilogram value is preserved internally for analytics and compliance. You can browse all related mass calculators on our free online weight converters page.
Because the conversion constants are exact—1 lb = 0.45359237 kg and 1 st = 14 lb—you can safely standardize kg across your stack and generate stones dynamically for user interfaces, PDFs, and exports. This avoids unit drift and keeps longitudinal trends comparable even as presentation formats change.
Stones to KG Formula
Exact relationship
Use either equivalent form:
kg = st × 6.35029318
// equivalently
kg = st × 14 × 0.45359237Example:
11.75 st × 6.35029318 = 74.61669 kgRelated Weight Converters
What is a Stone?
In modern usage, the international stone is defined exactly as 14 lb. Historically stones varied by commodity and locale, but those values are obsolete for personal weight or sports. This converter adopts the standardized definition so results align with contemporary medical and fitness systems.
What is a Kilogram?
The kilogram is defined via the Planck constant and is the foundation of the SI system. It is the authoritative unit for clinical documentation, dosing, and scientific publication. Even when your UI displays stones and pounds, store kilograms as the canonical value for auditability and exchange.
Step-by-Step: Converting st + lb to kg
- Combine stones and pounds: total_st = st + (lb ÷ 14).
- Multiply by 6.35029318 to get kilograms.
- Round for display according to your policy (e.g., 1 d.p. on consumer screens).
Example walkthrough:
st = 10, lb = 9
total_st = 10 + 9/14 = 10.642857
kg = 10.642857 × 6.35029318 = 67.62 kg (rounded)Common Conversions
Everyday quick checks
| st | kg |
|---|---|
| 7 | 44.45205 |
| 8 | 50.80235 |
| 9 | 57.15264 |
| 10 | 63.50293 |
| 11 | 69.85322 |
| 12 | 76.20352 |
| 13 | 82.55381 |
| 14 | 88.90410 |
| 15 | 95.25440 |
Precision, Rounding & Significant Figures
Operational rounding
For public reporting, round to 0.1 kg or to the nearest 0.5 kg depending on your policy. Internally keep more precision to preserve trend analysis and avoid accumulation of rounding error in repeated computations.
Consistent documentation
Standardize column names (e.g., weight_st, weight_lb, weight_kg), convert once at ingestion or presentation (not both), and annotate constants in tech docs: “1 st = 14 lb = 6.35029318 kg; 1 lb = 0.45359237 kg.” This practice makes audits and data exchange painless across systems.
Where This Converter Is Used
- 🏥 Clinics & EHRs: Intake forms may use stones/pounds; records standardized to kilograms.
- 🏋️ Fitness apps: UK/IE users track weight in stones; analytics and goals computed in kg.
- 🏉 Sports media: Athlete bios and weigh-ins shown in stones with SI equivalents for press kits.
- 🛍️ Retail & e-commerce: Size charts and equipment specs localized for regional audiences.
- 📈 Analytics: BI tools aggregate in kg for comparability across geographies and time.
Quick Reference Table
| kg | st |
|---|---|
| 50 | 7.87365 |
| 60 | 9.44838 |
| 70 | 11.02311 |
| 75 | 11.81100 |
| 80 | 12.59838 |
| 90 | 14.17311 |
| 100 | 15.74730 |
Frequently Asked Questions
What is the exact formula to convert stones to kilograms?
The international stone is fixed at 14 avoirdupois pounds, and each pound is exactly 0.45359237 kg. Multiply stones by 6.35029318: kg = st × 6.35029318. For mental math, 6.35 is a handy approximation, but publish the exact factor in methods or footnotes when precision matters.
How do I convert stones and pounds to kilograms (e.g., 11 st 11 lb)?
First fold pounds into stones: total_st = st + (lb ÷ 14). Then multiply by 6.35029318. Example: 11 st 11 lb → 11 + 11/14 = 11.785714… st → × 6.35029318 = 74.92 kg (rounded). This approach keeps results consistent with weigh-in sheets and EHR systems.
Why do some countries still prefer stones for body weight?
Stones are culturally familiar in the UK and Ireland, appear in sports commentary and media, and many consumers think in stones and pounds for personal weight. Healthcare and science remain SI-first (kg). Using a converter lets you communicate clearly to both audiences without sacrificing accuracy.
What level of precision should I display?
For public UI, one decimal place in kilograms is common (e.g., 74.9 kg). For clinical use, keep the internal canonical value with more precision and round once at the presentation layer. Publish a rounding policy so charts, emails, and PDFs stay consistent.
Is converting via pounds (st → lb → kg) the same as direct st → kg?
Yes. You can multiply stones by 14 to get pounds, then multiply pounds by 0.45359237 to get kilograms. Direct conversion (st × 6.35029318) is simpler and avoids extra rounding steps, but both methods are equivalent because the constants are exact.
Can I rely on historical ‘stone’ values from old documents?
Historically, some regions used different stones for commodities. In modern practice for personal weight and sports in the UK/IE, the ‘international stone’ is standardized at 14 lb. This converter uses that fixed definition, aligned with international pounds.
Do sports and fitness apps need both kg and stones?
Often yes. Store canonical kg for analytics and interoperability; expose stones & pounds for UK/IE-facing screens. This avoids unit drift and supports exporting to medical, academic, or international formats without re-processing historical data.
What’s the best way to show stones + pounds alongside kilograms?
Show kg as the primary SI value and a secondary line like ‘≈ 11 st 11 lb’. For mobile dashboards, you can offer a quick toggle between displays. Internally, keep the raw kg value and compute stones/pounds on the fly for consistent rounding.
Is this converter suitable for weight-class sports?
Yes. Many weight-class sports publish public-facing results in stones & pounds for local audiences while officials track kilograms. Keep official measures in kg and use stones only for display—your audit trail remains reproducible.
Tips for Working with Stones & Kilograms
- Keep kilograms canonical in databases; compute stones/pounds for front-end display to prevent drift.
- When printing or emailing, show both values and your rounding rule (e.g., ‘rounded to 0.1 kg’).
- For UX, allow users to input either stones or stones+lb and convert consistently to kg behind the scenes.
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