Practical Reticle Use While Traveling

Paws To Peaks
Jun 20
5 min read

Updated: Jun 27

Compact and sharp - the Solo makes quick field measurements easy

Measuring distance and object size using a reticle-equipped monocular

We often measure distances during our trips. It happens almost automatically while observing a distant object - a person paddling a kayak or a climber on a mountain ridge. We also use these measurements during long-range precision shooting training. In this case, accurate distance calculation is essential to apply the proper correction.

Recon R/T - serious ranging power that still fits in your side pocket

Of course, a small laser rangefinder can be used for that. Even though its size and weight aren’t really a problem, we usually take small monoculars with us instead. A pocket-sized monocular easily fits in a jacket or pants pocket, and it goes with us everywhere: when walking the dog, hiking in the mountains, or during any other trip.

Construction rangefinder on a tripod. Fieldwork begins where theory stops

Checking distance with a rangefinder is a great way to verify your calculations. After years of using a construction model, I bought one from a Chinese marketplace. It was several times cheaper - and several times better. Faster readings, works from the hand, even in bright sunlight or light rain. Definitely worth testing and comparing for yourself. How to measure distance with a monocular?

The key element here is the reticle - a scaled crosshair visible in the eyepiece while observing a target. High-precision scopes used for long-range shooting are equipped with more advanced reticles. But in this article, we’ll focus on compact monoculars that offer plenty of practical features for anyone who enjoys traveling.

Target size in mils? Check. Quick math gives the distance - no electronics needed

What is a mil (milliradian)?

The reticles in these monoculars are usually marked in milliradians, often called simply mils.

Simply put, a milliradian is a way to measure an angle - how wide something appears from where we’re standing.

Imagine standing still and looking far ahead.
If we drew a fan-shaped arc in front of us, a milliradian would define the width of that fan at a certain distance.
1 milliradian means that two objects, separated by 1 mil on the reticle at a distance of 1000 meters, are actually 1 meter apart in reality.

So:

1 mil = 1 meter at 1000 meters.

Or to put it differently: if something shifts by 1 mil in the reticle, it equals 0.5 meters at 500 meters, 2 meters at 2000 meters, and so on.

Use the scale for calculations, or match silhouettes to human figures for instant range approximation

How to calculate distance using a mil-based reticle?

The crucial thing is knowing the size of the object you’re observing - or at least part of it.

For example:

A human head: about 30 cm high,
A standard door: about 200 cm high,
An off-road car tire with a wheel: about 70 cm,
A small car’s height: around 150 cm.

Of course, it’s a great idea to measure your own dog, bicycle, or tent, since you may easily spot them from a distance during your trips.

Once you know the size of the object, stabilize your monocular (resting it on a rock, tree, or backpack) and align the reticle with the object to check how many mils it covers.

Let’s say you’re observing a hiker setting up a tent on the other side of the river. His head fills 3 full marks on the reticle’s vertical scale, meaning 3 mils (you can measure anywhere on the reticle - it doesn’t have to be in the center).

Here’s the simple formula for calculating distance:

Distance (m) = (Object size in cm ÷ Mils) × 10

In our case:

(30 ÷ 3) × 10 = 100 meters

The real fun begins when you and your partner both have monoculars and start comparing observations and calculations.

Below, I’ve prepared a table with several example objects, showing their estimated height and how many mils they would cover when observed from 100 and 1000 meters.

Object	Height (cm)	Mils at 100 m	Mils at 1000 m
Adult human	180	1.8	0.18
Child (approx. 8 years old)	130	1.3	0.13
SUV wheel (including tire)	75	0.75	0.075
Deer (stag, shoulder height)	130	1.3	0.13
2-person tent	110	1.1	0.11
Camping table	70	0.7	0.07
Diving tank 15L	70	0.7	0.07
Off-road vehicle	185	1.85	0.185
ACD dog (shoulder height)	50	0.5	0.05
Standard door (external)	200	2.0	0.20

Note:The same method works for measuring width or length of objects.

A practical example

Once we tried a slightly more advanced version of this game. We wanted to measure the height of a building about 400 meters away. We didn’t know either the distance or the size of the building - but there was a large German Shepherd walking in the yard. We estimated its shoulder height at around 60 cm. Based on that, we calculated the distance.

Once we had the distance, calculating the building's size (in this case - the height of the mountain chalet) was simple.

Formula for calculating object size if distance is known:

Object size (cm) = (Distance in m × Mils) ÷ 10

What equipment do we use for travel measurements?

We use two types of Vortex monoculars:

The smaller SOLO, with 8x magnification and a 36mm objective lens.
The larger (but still very portable) RECON, with 15x magnification and a 50mm lens.

Our go-to scopes - different size, same task: precise field measurements.

The Solo never leaves my pocket - it’s always with me. The Recon usually stays in the backpack but offers one significant advantage: it can easily be mounted on a tripod, which is very useful.

I use the Recon most often as a spotting scope during long-range shooting sessions. If the ground near the targets is sandy, it works perfectly for spotting misses and splashes when calling corrections.

Recon’s reticle is rotated by default - we fixed it the simplest way: rotate the scope

Technical Note - An Odd Design Choice

In the Recon R/T, the reticle is rotated 90° relative to the mounting rail. We asked the manufacturer why - they had no answer. Mounted normally on a tripod, the horizontal scale ends up vertical, making precise spotting awkward.

The fix is simple, though rarely mentioned: rotate the optic 90° in the mount. This aligns the reticle properly with the horizon, restoring normal measurement workflow and your neck.

No grid in the Yukon, but it helps us remember how small we are — especially at night

When we travel with our Land Cruiser, we also take a much larger scope - one that offers up to 100x magnification. Far away from cities, under clear skies, we often spend evenings watching stars and the moon. Even though it’s an amateur device, it allows us to take our private little interstellar journeys.

Conclusion Distance measurement isn’t just for shooting. It’s a simple, useful skill that comes in handy more often than you’d expect - whether you’re out walking the dog, pitching a tent, or trying to figure out how much climbing is still ahead.

You don’t need fancy gear or a military background. Just a reticle, a bit of curiosity, and a few tries. After that, you stop just looking at the landscape - you actually start reading it. And that’s a pretty satisfying way to spend your time outdoors.