Sight adjustment
Scope Elevation Travel Calculator
Quick answer
Only about half a scope total elevation travel sits above mechanical centre, and zeroing eats into that before you dial a single click. A scope with 60 MOA of total travel gives you roughly 30 MOA up, and a 20 MOA canted base adds 20 more by moving zero low in the erector range.
Running out of elevation is the failure that stops a rifle reaching distance, and it is almost always discovered at the range rather than predicted at the bench. The arithmetic is simple enough to do before you buy anything.
A scope publishes a total elevation travel figure, and that total spans the full range from the bottom of the erector to the top. Roughly half of it sits above the mechanical centre, and that half is all you can dial up. A rifle whose bore is not perfectly aligned with the base consumes some of it just to reach zero.
The honest caveat, and the reason this calculator asks you to enter the figure: many manufacturers do not publish total elevation travel at all. Where yours does not, the number is in the manual or in the specification sheet on the maker website, and we would rather ask you than print an estimate.
Elevation travel calculator
Usable up travel
The formula
usable up travel = (total travel / 2) + base cant - travel consumed reaching zero
Canted bases and mounts that buy travel back
Top matches update when you change your numbers.
A canted base is roughly a tenth the price of a scope with more travel, and it solves the same problem on a rifle that genuinely needs the reach.
Weaver Extended Multi-Slot Base, Remington 700 Short Action, 20 MOA
$53.79Twenty MOA of built-in cant on a Remington 700 short action, which converts unused down travel in the erector into usable up travel for distance.
Best for: a Remington 700 short action shot past 600 yards
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EGW Ruger 10/22 Picatinny Rail Scope Mount, 20 MOA
$35.99Twenty MOA of cant on a rimfire, which sounds excessive and is exactly right: .22 LR drops so steeply that a 100 yard zero on a flat base can run a scope out of elevation.
Best for: precision rimfire shot past 100 yards
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Outerimpact Howa 1500 and Weatherby Vanguard Long Action Picatinny Base, 20 MOA
$49.95A canted base for the Howa 1500 and Vanguard pattern, which is one of the most common long range budget builds and is poorly served by generic bases.
Best for: a Howa 1500 or Weatherby Vanguard long range build
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Arken Optics 30mm 20 MOA Rigid Precision Scope Mount
$69.99Twenty MOA of cant built into a one piece mount, so you get the elevation back without also needing a canted base underneath it.
Best for: reaching distance without replacing the rifle base
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Burris Signature Zee 30mm High Rings, Matte
$49.77The synthetic inserts let you deliberately add cant to a mount, which is how you buy back elevation travel without replacing the base.
Best for: adding elevation without a canted base
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Nightforce Standard Duty Aluminium Mounting Scope Base
$59.00Nightforce machining on a one piece base, which is the part that everything else on the rifle is squared off. Getting this part right removes a class of problem permanently.
Best for: a precision rifle where the base must be dead square
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Vortex Viper PST Gen II 5-25x50 First Focal Plane Riflescope, EBR-7C MOA
$999.00 Full specificationsThe reference precision scope in this price band. The turrets return to zero reliably, which sounds like a low bar and is the single thing cheap scopes fail at after a season.
Best for: a precision rifle that will be dialled hard and often
Check price on AmazonWhat each combination of travel and base cant gives you
Assuming 5 MOA consumed reaching zero, which is a realistic figure for an ordinary rifle. A poorly aligned receiver can consume far more.
A scope with 60 MOA of total travel on a flat base gives about 25 MOA of usable come-up after zeroing, and the same scope on a 20 MOA base gives about 45.
Sourced figure
| Total travel | Half of it | Flat base | 10 MOA base | 20 MOA base | 30 MOA base |
|---|---|---|---|---|---|
| 40 MOA | 20 MOA | 15 MOA | 25 MOA | 35 MOA | 45 MOA |
| 50 MOA | 25 MOA | 20 MOA | 30 MOA | 40 MOA | 50 MOA |
| 60 MOA | 30 MOA | 25 MOA | 35 MOA | 45 MOA | 55 MOA |
| 70 MOA | 35 MOA | 30 MOA | 40 MOA | 50 MOA | 60 MOA |
| 80 MOA | 40 MOA | 35 MOA | 45 MOA | 55 MOA | 65 MOA |
| 100 MOA | 50 MOA | 45 MOA | 55 MOA | 65 MOA | 75 MOA |
Arithmetic on the published total. The assumption that half the travel sits above mechanical centre is the convention, and a rifle whose bore is not square to the base will not match it.
Why a canted base works, and when it backfires
A canted base tilts the whole scope down at the front. To reach zero, the erector then has to sit low in its range rather than near the middle, which leaves far more room above it. Unused down travel becomes usable up travel, and 20 MOA of cant is 20 MOA of extra reach for the price of a base.
The failure mode is real and it catches people. On a rifle that will never shoot past 300 yards, a 20 MOA base can make it impossible to zero at all, because the erector runs out of DOWN adjustment before the point of impact reaches the line of sight. You end up shooting permanently high with the turret bottomed out.
The rule: a canted base belongs on a rifle that genuinely needs the reach. On a woods rifle it is worse than useless.
What to do when you are short
In increasing order of cost, which is roughly the opposite of the order most people try.
- Check your rings and base are square first. A large chunk of "not enough elevation" is actually a misaligned mount consuming travel to reach zero. Alignment bars and lapping cost far less than a base.
- Add a canted base. Twenty MOA for the price of a part, on a rifle that will use it.
- Use adjustable inserts. A ring insert system lets you add cant without replacing the base, which suits an action with no canted base available.
- Hold rather than dial. A reticle with holdover marks costs nothing in travel, because you are not moving the erector at all. On a first focal plane scope those holds are valid at any magnification.
- A scope with a larger tube. The expensive answer, and the one that actually buys more travel. Note that a larger tube does not gather more light, which is a separate and persistent myth.
Sources
- Manufacturer published total elevation travel figures, where they are published
- Manufacturer published base cant figures from the product listings in our catalog
Frequently asked questions
How much elevation travel do I need?
Work out the come-up your load needs at the farthest distance you realistically shoot, then compare it to half your scope published total travel minus whatever zeroing consumed. If the margin is not comfortable, add a canted base rather than a bigger scope, because it costs a tenth as much and solves the same problem.
Does a 20 MOA base really add 20 MOA?
Effectively yes. It tilts the scope down at the front so zero sits low in the erector range, converting unused down travel into usable up travel. The gain is close to the rated cant. What it does not do is create adjustment that was never in the scope, so a scope with very little total travel is still limited.
Can a 20 MOA base stop me zeroing?
Yes, and this is the trap. On a rifle shot only inside 300 yards, the erector can run out of down adjustment before the point of impact reaches the line of sight, leaving you permanently high with the turret bottomed out. A canted base belongs only on a rifle that will genuinely use the extra reach.
Why does only half the travel count?
Because total travel spans from one mechanical stop to the other, and zero normally sits somewhere near the middle. Only the portion above where zero ends up is available as come-up. Any misalignment between bore and base shifts zero away from centre and eats into that half before you dial anything.
My scope does not publish its total travel. What now?
Check the manual and the specification page on the maker website, since many publish it there rather than in the listing. Failing that, count the total turns from stop to stop and multiply by the click value and clicks per turn. We will not print an estimate for your model, because a wrong number here is worse than no number.
Is a 34 mm tube worth it for the extra travel?
Only once you have proven that a 30 mm tube plus a canted base runs out at the distance you actually shoot. A larger tube leaves room for the erector to move further, which is a real benefit. It does not gather more light and does not make clicks finer, which are the two things people usually assume they are buying.
Researched, not professional advice. This page is compiled from published manufacturer specifications, published optical and ballistic formulas, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are shooter convention rather than sourced numbers, and they are labelled that way wherever they appear. Ballistic figures come from a point mass model using the ballistic coefficient the maker publishes, so treat them as a starting point and confirm them on paper at a measured distance. Confirm your firearm is unloaded with the action open before you mount, level, torque or bore sight anything. Verify a zero only on a supervised range or a safe, legal backstop, know what lies beyond your target, and follow the law where you hunt and shoot, including rules on land access and permitted cartridges.