Curvature & Refraction Correction Calculator
Earth-curvature and refraction corrections for long level sights.
At 1 km the Earth falls away 78 mm; the atmosphere bends the line back a seventh. Balanced back/foresight distances cancel the whole thing — the oldest trick in levelling.
Formula
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Curvature & Refraction Correction Calculator is a free curvature correction for surveyors, civil engineers and property buyers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Curvature & Refraction Correction Calculator
Earth-curvature and refraction corrections for long level sights. The calculation implements combined = 0.0673·d² (d in km, answer m) (Geodetic levelling corrections). At 1 km the Earth falls away 78 mm; the atmosphere bends the line back a seventh. Balanced back/foresight distances cancel the whole thing — the oldest trick in levelling.
How to use Curvature & Refraction Correction Calculator
- 1Enter Sight distance in m.
- 2Read Curvature correction, Refraction (−1/7th), Combined correction instantly — no submit button needed.
- 3Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Curvature & Refraction Correction Calculator?
- ✓Implements the standard formula — combined = 0.0673·d² (d in km, answer m)
- ✓Reference cited on-page: Geodetic levelling corrections
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Curvature & Refraction Correction Calculator use?+
It computes combined = 0.0673·d² (d in km, answer m), per Geodetic levelling corrections. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
At 1 km the Earth falls away 78 mm; the atmosphere bends the line back a seventh. Balanced back/foresight distances cancel the whole thing — the oldest trick in levelling.
Are regional land units exact?+
Conversion factors follow state revenue-department values noted on the tool. Units like bigha and katha vary by region, so always confirm the local factor named in your land records.
Is the Curvature & Refraction Correction Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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