Solverly

Miles ↔ Kilometers Converter

The Miles ↔ Kilometers Converter gives you instant, accurate distance changes between U.S. and metric units. It’s useful for travel planning, interpreting car odometers or cycling computers, setting race paces, and aligning maps or route notes that mix measurement systems.

Enter a value in either unit to immediately see the equivalent in the other—no formulas to remember, just clear numbers you can act on. The goal is seamless unit translation so you can compare routes, estimate travel times, and communicate distances with confidence. Adjust the number as needed and keep your itinerary, training plan, or project moving.

Convert miles (mi) to kilometers (km) and back — with race presets, rounding, and instant results.

Convert miles and kilometers instantly. Type a value to get results.

We compute using 1 mile = 1.609344 kilometers for precise conversions.

Enter distance

Type a value in miles to convert to kilometers.

Or type a value in kilometers to convert to miles.

Race distance presets

Enter miles or kilometers to see the conversion and race table.

Miles ↔ Kilometers Results

Miles (mi)
—
Kilometers (km)
0
RaceKilometers (km)Miles (mi)
5K53.11
10K106.21
Half21.113.11
Marathon42.226.22

Results interpretation

We convert distances using the exact factor 1 mile = 1.609344 kilometers. The rounding control adjusts how many decimal places we display; the underlying math is done at full precision before rounding output.

  • Training & racing. Rounding to 1–2 decimals is common (e.g., 10.1 km); race standards use fixed distances like 5.00 km, 10.00 km, 21.0975 km, and 42.195 km.
  • Navigation & travel. Use fewer decimals for readability on road signs and maps.
  • Engineering & surveying. Increase decimals when higher precision is required.

How it works

Formulas, steps, and assumptions

Conversion formulas

mi → km: km = mi × 1.609344
km → mi: mi = km ÷ 1.609344

Steps

  1. Enter a value in miles or kilometers.
  2. Choose the rounding you want (0–6 decimals).
  3. (Optional) Tap a race preset to fill a standard distance.
  4. Review the converted result and the quick race table.
  5. Use “Copy link with inputs” to share or revisit later.

Assumptions & notes

  • We use the international mile definition (exactly 1.609344 km).
  • Rounding only affects display; math uses full precision.
  • Presets use official race distances.

Limitations

  • We don’t account for course measurement tolerances.
  • Decimal rounding is a display feature, not a measurement method.

Use cases & examples

Marathon planning

A marathon is 42.195 km. In miles, that’s 26.22 mi. We can set decimals to 2 for easy reading on training plans.

5K to miles

A 5K is 5.00 km, which equals 3.11 mi (about 3.11 miles).

Road trip conversion

Driving 120 miles? That’s 193 km when rounding to 0 decimals, useful for quick mental math on highway signs.

Miles ↔ Kilometers FAQs

What’s the exact miles to kilometers conversion?

We use 1 mile = 1.609344 kilometers (exact by definition).

What rounding should we use?

For training logs, 1–2 decimals is common. For official race distances, keep the standard exact values. Use more decimals for technical work.

Why do some sources show slightly different numbers?

Older charts sometimes used 1.61 or 1.6 km per mile. We stick to the exact factor 1.609344.

Can we convert negative values?

Yes—this can be useful for elevation deltas or directional offsets.

Do race courses ever vary?

Standards are fixed (5K, 10K, half, marathon), though small measurement tolerances may appear.

Does rounding change the math?

No. We compute in full precision and round only what’s displayed.

How do the presets work?

They fill official race distances so we can convert quickly without typing.

Can we share our inputs?

Yes—use “Copy link with inputs” to create a sharable URL with your values and rounding.

Miles to Kilometers: practical conversion, race standards, and real-world tips

Distance conversion between miles and kilometers shows up everywhere—from training plans and race websites to road trips, engineering specs, and GPS traces. We built our converter around the exact definition 1 mile = 1.609344 kilometers so results are consistent, sharable, and easy to read with a rounding control that fits the task.

Why 1.609344?

The international mile has been standardized to precisely 1.609344 km since the mid-20th century. Using this constant eliminates small discrepancies that appear when people round to 1.61 or 1.6.

Converting both ways: mi → km and km → mi

The two formulas are linear inverses: km = mi × 1.609344 and mi = km ÷ 1.609344. Because the factor is exact, any difference you notice between sources comes down to rounding choices.

Rounding for readability

Choose 0–1 decimals for highway signs or quick travel estimates. Use 1–2 for running logs and bike computers. Go to 3–4+ when you need engineering-level precision.

Race distances and presets

We include presets for the most requested standards: 5K (5.00 km), 10K (10.00 km), half marathon (21.0975 km), and marathon (42.195 km). These values are fixed and used internationally, making them perfect reference points for pace charts and plan conversions.

Training, pacing, and GPS drift

GPS devices can drift due to tree cover, buildings, and sampling frequency. If your watch reports 9.96 km for a 10K, that’s not unusual. Keep rounding consistent across your log so weekly totals stay comparable.

Travel and road signage

Crossing borders often means switching units. A quick conversion keeps expectations realistic—especially for battery, charging, or fuel stops where range estimates rely on distance.

Engineering and compliance

Specs may require quoting both mi and km. Use higher decimals for submission copies while keeping a rounded version for customer-facing docs.

Common pitfalls

  • Mixing approximate factors (1.6 or 1.61) with exact factors causes drift on longer distances.
  • Double rounding—converting, rounding, then reconverting—compounds error. Convert once from the original.
  • Switching rounding settings mid-project makes comparisons harder.

Checklist for consistent conversions

  • Pick the factor (1.609344) and stick to it.
  • Choose a rounding that matches your context and keep it consistent.
  • Use presets for race distances to avoid typos.
  • Share a link with inputs when collaborating.

Extending the workflow

For pace planning, pair conversions here with our running pace and race-time tools. For travel, combine with speed and fuel/EV range calculators so the whole itinerary uses the same unit system end-to-end.

How to convert miles and kilometers

  1. Enter a value in either miles or kilometers.
  2. Select a rounding level that fits your use case.
  3. (Optional) Tap a race preset to fill a standard distance.
  4. Read the converted value and scan the quick race table.
  5. Copy a link with your inputs to save or share.