How this calculator works
This tool applies Hubble's Law, v = H0 x d, where v is a galaxy's recession velocity, d is its distance, and H0 is the Hubble constant — the current expansion rate of the universe. Enter a distance and a value for H0, then click Calculate to see the recession velocity, its size relative to the speed of light, an approximate redshift, and the Hubble time. Click Clear to reset to the defaults.
Understanding the inputs
Distance can be entered in megaparsecs (Mpc, the standard astronomical unit used with H0), million light-years, or billion light-years — the calculator converts internally to Mpc before applying the formula. The Hubble constant is typically quoted between about 67 and 74 km/s/Mpc; the exact value is an active area of research (the "Hubble tension" between early-universe and local measurements), so the field defaults to 70 km/s/Mpc as a common round-number estimate.
Interpreting the results
Recession velocity and its percent of light speed show how fast the object is receding due to cosmic expansion (not through motion in space, but because space itself is stretching). The redshift estimate uses the simple non-relativistic relation z ≈ v/c, which is accurate only when v is much smaller than c; the status panel flags when that assumption is getting strained. The Hubble time is independent of distance — it only depends on H0 — and represents how old the universe would be if it had always expanded at today's rate.
Frequently Asked Questions
What is Hubble's Law?
What is the Hubble constant?
How is redshift related to recession velocity?
What is the Hubble time?
Common Tip Percentages
| Service | Typical Tip Range | Notes |
|---|---|---|
| Restaurant (sit-down) | 15–20% | 20%+ for exceptional service |
| Food delivery | 10–20% | Consider extra for long distances |
| Taxi / rideshare | 10–20% | More for assistance with luggage |
| Hotel housekeeping | $2–5/night | Leave daily, not just at checkout |
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General Household Budget Ratios (50/30/20 Rule)
| Category | % of Net Income | Examples |
|---|---|---|
| Needs | 50% | Rent, groceries, utilities, insurance |
| Wants | 30% | Dining out, entertainment, hobbies |
| Savings / Debt | 20% | Emergency fund, retirement, extra payments |
Common Measurement Conversions for Everyday Use
| Quantity | US / Imperial | Metric Equivalent |
|---|---|---|
| 1 cup | 8 fl oz | 237 mL |
| 1 pint | 16 fl oz | 473 mL |
| 1 quart | 32 fl oz | 946 mL |
| 1 gallon | 128 fl oz | 3.785 L |
| 1 lb | 16 oz | 453.6 g |
| 1 ft | 12 in | 30.48 cm |