ADR Assumptions: What to Document

An Architecture Decision Record (ADR) should document the assumptions that, if proven wrong, would most likely invalidate the decision. These are the implicit or explicit beliefs about the world, the system, the team, or the business that the chosen architecture depends on. By writing them down, you turn a static decision into a testable hypothesis and give future engineers a clear trigger for when to revisit it.

Formula

The calculator above computes average pace and speed from a finish time and distance. The formulas are:

• Pace = Finish time (minutes) ÷ Distance (km), expressed in minutes per kilometer.
• Speed = Distance (km) ÷ (Finish time (minutes) ÷ 60), expressed in kilometers per hour.

Where:

• t = finish time in minutes
• d = distance in kilometers

Worked Example

Using the default values: finish time = 50 minutes, distance = 10 km.

1. Pace = 50 ÷ 10 = 5.00 min/km
2. Speed = 10 ÷ (50 ÷ 60) = 10 ÷ 0.8333 = 12.00 km/h

The calculator returns an average pace of 5.00 min/km and an average speed of 12.00 km/h.

When to Use This Calculator

Use this tool when you have a target finish time and want to know what pace to hold, or when you have completed a run and want to convert your time and distance into a comparable speed. Runners, cyclists, and walkers all use this basic relationship to plan training sessions or race strategies. For example, if you want to finish a 5 km parkrun in under 30 minutes, you need a pace faster than 6.00 min/km. The calculator works for any distance and time, as long as you keep the units consistent.

How to Read the Result

The pace result tells you how many minutes each kilometer takes. A lower pace number means faster running. The speed result tells you how many kilometers you cover in one hour. These two numbers are reciprocals of each other (with unit conversion), so you only need one for most planning. Coaches often use pace for shorter distances and speed for longer endurance efforts, but both describe the same effort. Remember that this is an average – real runs include hills, stops, and variations in effort, so your instantaneous pace will fluctuate around this number.

Common Mistakes

• Mixing units: If your distance is in miles, convert to kilometers first (1 mile = 1.60934 km) or use a miles-based formula. Entering miles into this calculator will give a pace that is too fast.
• Using seconds instead of minutes: If your finish time is 50 minutes and 30 seconds, convert to 50.5 minutes before entering. Forgetting the seconds can change your pace by several seconds per kilometer.
• Rounding too early: If you round the pace to 5.0 min/km and then compute speed from that rounded number, you get 12.0 km/h, but the exact speed is 12.0 km/h anyway. However, for longer distances, rounding the pace to one decimal can cause a noticeable error in speed.
• Assuming constant pace: The average pace does not tell you how to distribute your effort. A negative split (running the second half faster) is a common strategy, but the average remains the same.

Limitations of the Formula

This is a pure arithmetic relationship, so it has no built-in assumptions about fitness, terrain, weather, or elevation. It only converts time and distance into average pace and speed. It cannot predict your finish time from a given pace unless you also know the distance. It also does not account for stops – if you pause your watch, the time you enter should be moving time, not elapsed time, for an accurate average pace. For race planning, consider that most runners run slightly longer than the official distance due to tangents and turns, so add a small buffer to your target pace.

Frequently Asked Questions

What is a good average pace for a beginner runner?

There is no universal answer, as it depends on age, fitness, and experience. A common benchmark is that a 30-minute 5 km (6:00 min/km) is a reasonable goal for a new runner, while a 25-minute 5 km (5:00 min/km) is quite good. Use the calculator to see what pace you need for a target time, then train consistently.

How do I convert pace to speed on a treadmill?

Most treadmills show speed in km/h or mph. To convert pace (min/km) to speed (km/h), divide 60 by the pace. For example, 5:00 min/km = 60 ÷ 5 = 12.0 km/h. If your treadmill shows mph, first convert your pace to min/mile (multiply min/km by 1.60934) or convert the speed directly.

Does elevation gain affect my average pace?

Yes, uphill sections slow you down and downhill sections speed you up, but the average pace calculation does not account for this. If you are comparing runs on different courses, use a metric like GAP (Grade Adjusted Pace) that normalizes for elevation, but for a simple time-distance conversion, this calculator is sufficient.

Can I use this calculator for walking?

Absolutely. The same formula applies to walking. A typical walking pace is between 12 and 20 minutes per kilometer (3 to 5 km/h). Enter your walking time and distance to see your average speed.

How accurate is this for a marathon?

For a marathon (42.195 km), the calculator gives your required average pace. However, most runners cannot hold a perfectly even pace over 42 km due to fatigue. A common strategy is to aim for a pace slightly faster than your target in the first half, but many coaches recommend a negative split. Use the average as a baseline and adjust for your personal endurance profile.

What if I only know my speed in mph?

Convert mph to km/h by multiplying by 1.60934, then use the calculator with distance in kilometers. Alternatively, convert your distance to miles and use a miles-based pace formula. The key is to keep the units consistent.

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in t | Finish time | min | 50 | 0
in d | Distance | km | 10 | 0 | 100000
out pace | Average pace | min/km | t / d | 2
out speed | Average speed | km/h | d / (t / 60) | 2