Bathtub Curve
Calculate Bathtub Curve instantly with the exact formula and a worked example.
Bathtub Curve
Operating ageh
Early-life shape β1 (<1)
Early-life scale η1h
Random failures λper 10⁶ h
Wear-out shape β3 (>1)
Wear-out scale η3h
Hazard rate h(t)
29.8488per 10⁶ h
Phase
Useful life (normal operation)
Early failures
7.071per 10⁶ h
Random failures
20per 10⁶ h
Wear-out failures
2.778per 10⁶ h
Reliability up to t
83.92%
More about: Bathtub Curve
What it calculates
The “Bathtub Curve” calculator computes Hazard rate h(t) in per 10⁶ h from 6 parameters: operating age (h), early-life shape β1 (<1), early-life scale η1 (h), random failures λ (per 10⁶ h), wear-out shape β3 (>1), wear-out scale η3 (h).
A handy everyday calculator for daily tasks.
Example calculation
With parameters Operating age = 5,000 h, Early-life shape β1 (<1) = 0.5, Early-life scale η1 = 1,000,000 h, Random failures λ = 20 per 10⁶ h, Wear-out shape β3 (>1) = 3, Wear-out scale η3 = 30,000 h the result is 29.85 per 10⁶ h (Model: sum of three Weibull hazards).
How to use
- Enter operating age, early-life shape β1 (<1), early-life scale η1, random failures λ, wear-out shape β3 (>1) and wear-out scale η3 — each field above is adjustable with a slider.
- Hazard rate h(t) (per 10⁶ h) is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
Related calculators
FAQ
How is Bathtub Curve calculated?
The Bathtub Curve calculator computes Hazard rate h(t) (in per 10⁶ h) from operating age, early-life shape β1 (<1), early-life scale η1, random failures λ, wear-out shape β3 (>1), wear-out scale η3. Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the Bathtub Curve calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
More calculators in this category
Explore related free tools