What does ppm mean for quartz accuracy?

PPM is parts per million. 1 ppm means 1 part error in 1,000,000. Time error per day = |ppm| × 86,400 / 1,000,000 seconds.

How do temperature swings affect error?

Temperature changes can add drift. A quick estimate uses a parabolic coefficient around 25 °C: Δppm ≈ k × (T − 25)^2. For tuning‑fork crystals k ≈ −0.034 ppm/°C² (magnitude used for estimation). Always consult your device’s datasheet.

Should I add errors or use RSS?

For worst‑case budgeting, sum magnitudes (conservative). For typical expectations, a root‑sum‑square (RSS) of independent contributors is common. This tool shows both.

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PPM to Seconds/Day Calculator | Quartz Accuracy

Release time:

2025-10-08 15:13

PPM → Seconds/Day Converter for Quartz Frequency Accuracy

Turn ppm into human‑readable time drift for the frequency of quartz crystal. Use the simple converter for nominal specs, or the temperature estimator to budget worst‑case drift across your environment.

Scope: electronics only. If you’re new to timing, start with our Quartz Frequency Pillar, What Are Timing Devices? and the 32,768 Hz explainer.

PPM to seconds per day converter with temperature estimator

The One‑Line Formula

seconds/day = |ppm| × 86,400 / 1,000,000

That’s it. If a crystal or oscillator is specified at ±10 ppm, its nominal daily drift is about ±0.864 s/day. You can also verify with the SiTime PPM/Hz calculator.

Simple PPM → Time Drift

Error (ppm)

Result: 10 ppm ≈ 0.864 s/day

≈ 25.920 s/30 d · ≈ 5.256 min/year

Add Temperature Range (Estimator)

Ambient Min (°C) Ambient Max (°C) Temperature Coefficient k (ppm/°C²) Nominal Spec @25°C (ppm)

Estimated Δppm from temperature: — (worst of range)

Worst‑case sum: — ppm → — s/day

RSS estimate: — ppm → — s/day

Model uses |Δppm| ≈ |k| × max[(T_min−25)², (T_max−25)²]. For tuning‑fork quartz, a typical magnitude is |k|≈0.034 ppm/°C². Datasheet values vary; use vendor‑specific curves when available (TI notes −0.04 ppm/°C² typical, Epson shows compensated curves).

Worked Examples

#1 Wearable RTC (32,768 Hz)

Spec: ±10 ppm at 25°C. Environment: 0…40°C, tuning‑fork k≈0.034. Temperature adds ≈ — ppm → worst‑case ≈ — ppm (≈ — s/day). Suggested parts: FCO‑3K, FVT‑2S.

#2 Outdoor Sensor

Spec: ±5 ppm TCXO. Environment: −30…+70°C, vendor‑compensated. Temperature term is small, budget dominated by base ±5 ppm → ≈ 0.432 s/day.

#3 Lab/Network 10 MHz

OCXO at ±0.05 ppm nominal (50 ppb). Daily drift ≈ 0.0043 s/day. Temperature is oven‑controlled; aging dominates long‑term.

Talk to an Engineer Browse by Application (Selection Guide)

References & Further Reading

FAQ

What is ppm in simple terms?

One part in a million. 1 ppm means 1 µs of error per second, ~0.0864 s per day.

Does temperature multiply the ppm number?

Not directly. Temperature introduces additional ppm drift that depends on the crystal cut and compensation. Our estimator uses a parabolic approximation around 25°C.

Should I add worst‑case or use RSS?

For guarantees, sum magnitudes (worst‑case). For typical field behavior, estimate with root‑sum‑square (RSS) if error sources are independent.

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