Every time a round closes, two sentences appear in the same chat within minutes of each other: "the snapshot has already been taken", and "I was holding, why am I not eligible?"
Both can be true at once, because what most people picture when they hear "snapshot" is not what the rule actually computes. Fixing that needs no technique — only one fact: there are three ways to measure a snapshot, and they ask you to do opposite things.
This covers the general methods used to measure snapshot eligibility, across both exchange programmes and on-chain projects. Every round sets its own rules, counted scope, caps and regional eligibility, and those change — the round's current official announcement is always the authority (official pages cited here checked 2026-08-30). Nothing on this page is investment advice.
01The word "snapshot" misleads people
Snapshot suggests a shutter closing: whatever is in your account at that instant is what counts.
Some rounds do work that way. More of them measure how your balance behaved across a period — sampling it many times and averaging, or adding up daily balances and dividing by the number of days. The moment a rule moves from "an instant" to "a period", what you need to do inverts: not "fund before the deadline", but "keep it there throughout".
Held, still ineligible is usually not bad luck. It is what happens when you prepare for the first rule and run into the second.
02Three methods, three opposite preparations
| Method | How it computes | What you must do |
|---|---|---|
| Point-in-time | Balance at a stated time or block height | Be funded before it; free to move after |
| Randomised sampling | Many samples across the period (often several per hour), then averaged | Hold throughout; last-minute funding does nothing |
| Time-weighted average | Sum of daily balances ÷ days in the period | Early and long beats large and late |
The bottom two are the coarse and fine versions of one idea: both penalise money that arrives just in time. The difference is stark. Under a point-in-time rule, moving funds in an hour early ranks you alongside someone who held for a year. Once it averages, the share you want is the share you actually have to hold, for those days.
It also explains a familiar puzzle: why someone who held only a bit longer ends up with a visibly larger allocation. Under an averaging rule, time is a multiplier, not a threshold.
03Five ways holders still miss out
- Wrong location. Eligibility is usually tied to a specific product or account, not to "the coin is somewhere in my account". Held, but outside the counted scope, is the same as not held.
- Wrong timing. Funding in the back half of the period lets the empty first half drag the average down, and the final figure comes out far below what you assumed.
- Moved out mid-period. Even a few days away leaves a dent in the average. Also check whether the announcement says average or lowest balance observed during the period — under the latter, emptying the account once is enough to flatten the whole round, so it is worth looking for that sentence specifically.
- A non-balance condition failed. Verification status, region, or an account restriction — any of these can zero you out regardless of balance.
- Hit a cap. Many rounds apply a per-user calculation limit; balance beyond it produces no additional share, so gaps between larger holders get flattened.
The first one causes the most damage because it surfaces last — people usually discover it while hunting for a reward that was never coming. Where airdrops land covers the destination side in detail, and whether sub-accounts qualify handles the main-versus-sub question.
04Two verifiable examples: exchange and on-chain
Different worlds, same thing being penalised.
Exchange side. The official HODLer Airdrops announcement states that snapshots of user balances and total pool balances are taken multiple times at any point within each hour to derive users' hourly average balances in Simple Earn products (Flexible and/or Locked), and that rewards are calculated from historical snapshots taken at random periods after the announcement. It also requires completed account verification and an eligible jurisdiction, applies a per-user BNB calculation limit stated in each round's announcement, and distributes rewards to Spot Wallets within 24 hours of the announcement (checked 2026-08-30). Three properties in one paragraph: random, hourly-averaged, capped. Topping up after the announcement does not work by design.
On-chain side. The ZKsync airdrop documentation states that eligibility used a time-weighted average balance, calculated for each wallet by summing the daily balance and dividing by the total number of days in the snapshot period, which ran from the public mainnet launch on 24 March 2023 to 24 March 2024 — 366 days (checked 2026-08-30). Under that rule, funding in the final week barely registers against a 366-day average.
Two different platforms, two different settings, one shared idea: filter by time. That is simultaneously the barrier of such rules and their compensation to people who were already there.
05Working out which method a round uses
You do not have to guess. The announcement usually gives it away:
- A time stated to the minute, or a block height → leaning point-in-time.
- "Average balance", "hourly" → sampled and averaged.
- "Time-weighted", "snapshot period" → time-weighted average balance.
None of the three appears? Prepare for the strictest interpretation and treat it as a period. The cost of being wrong is asymmetric: mistake a point-in-time rule for an averaging one and you funded a few days early; mistake it the other way and you miss the round entirely.
06Four things to do beforehand
- Confirm the counted scope. Put the assets where the rules say, and do not reason from what seems obvious.
- Be early. Under any averaging rule, arriving early is itself part of qualifying.
- Do not move funds mid-period. If you must, work out how far it drags the average first.
- Check the cap. Balance above the limit earns nothing extra while still carrying its own opportunity cost — what an airdrop actually costs has the full arithmetic.
07A six-point check
- Find the sentence stating the formula, and decide first: instant, or period?
- Confirm which product or account the assets must sit in to count.
- Note the start and end of the period, and the date you first met the condition.
- Check the per-user cap; nothing above it needs funding.
- Verify the non-balance conditions: verification status, region, account limits.
- Wherever the rules are vague, prepare for the reading least favourable to you.
Once you are set up, go back to choosing among the four types for this round. And if what arrives is a message saying "click here to claim your snapshot reward", run it past how to spot a fake airdrop first — real programmes do not DM you snapshot results.
Snapshot rules are set by each programme and can change at any time. This page explains common formulas and how to read a rule; it does not represent any round's current terms and does not guarantee that preparing this way makes you eligible. Assets held to qualify carry price risk, and a reward can be worth less than what it cost to earn. This is not investment advice — whether to join is your call and your risk.
Sources checked 2026-08-30. The two official pages above illustrate the shape of each method; their specific parameters apply to those programmes only and do not transfer to other rounds.