Vertical Curve Length Calculator
Crest curve length for sight distance from grades and SSD (K-value method).
K bundles all the sight-distance trigonometry into one tabulated number per speed — multiply by the grade change, done. Sag curves use headlight K-values instead.
Formula
Vertical Curve Length Calculator is a free vertical curve 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 Vertical Curve Length Calculator
Crest curve length for sight distance from grades and SSD (K-value method). The calculation implements L = K × A, A = |G₁ − G₂| (AASHTO/IRC vertical curve tables). K bundles all the sight-distance trigonometry into one tabulated number per speed — multiply by the grade change, done. Sag curves use headlight K-values instead.
How to use Vertical Curve Length Calculator
- 1Enter Approach grade in %.
- 2Enter Departure grade in %.
- 3Enter K-value for design speed in m/% (Crest SSD K: 50 km/h→11 · 80→44 · 100→105 (IRC/AASHTO)).
- 4Read Algebraic grade change A, Curve length required instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Vertical Curve Length Calculator?
- ✓Implements the standard formula — L = K × A, A = |G₁ − G₂|
- ✓Reference cited on-page: AASHTO/IRC vertical curve tables
- ✓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 Vertical Curve Length Calculator use?+
It computes L = K × A, A = |G₁ − G₂|, per AASHTO/IRC vertical curve tables. 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?+
K bundles all the sight-distance trigonometry into one tabulated number per speed — multiply by the grade change, done. Sag curves use headlight K-values instead.
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 Vertical Curve Length 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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