Choosing when and what to upgrade is one of the most important decisions in Dig a Garden. With over 25.7 million visits and a stellar 98.3% rating, this Roblox drill simulator by The Heap has captivated players with its satisfying core loop: buy drills, place them on your plot, dig up items, and sell those items for Diglets to buy even better drills. However, progressing efficiently requires more than just buying the most expensive drill you can afford. This guide covers the complete drill upgrade path with specific advice on timing, priority, and the underlying mechanics that make certain upgrades better than others.
The Drill Upgrade Path & Specializations
Every drill in Dig a Garden follows a clear progression path. Understanding this path helps you avoid wasting Diglets on the wrong upgrades. While tier rating (C, B, A, S) gives a general idea of a drill's power, each model also possesses a hidden specialization that dictates its actual performance in different scenarios.
| Stage | Drill | Tier | Cost | Specialty |
|---|---|---|---|---|
| 1 | Starter Drill | C | Free | Starting Out |
| 2 | Group Drill | A | Free (join group) | Free Group Perk |
| 3 | Standard Borer | B | ~5K Diglets | Reliable Mid-Game |
| 4 | Turbo Digger | A | ~20K Diglets | Fast Dig Speed |
| 5 | Deep Piercer | A | ~50K Diglets | Rare Item Discovery |
| 6 | Mega Borer | S | ~100K Diglets | Max Diglets/Hour |
| Premium | Galaxy Drill | S | Robux (off-sale) | Legendary Hunting |
To better understand how these specializations affect your gameplay, here is a detailed comparison of how each drill interacts with the game's four item rarity tiers (Common, Unusual, Scarce, Legendary):
| Drill | Common Item Rate | Unusual Item Rate | Scarce Item Rate | Legendary Chance | Best Use Case |
|---|---|---|---|---|---|
| Starter Drill | 95% | 5% | 0% | 0% | Early Diglet farming |
| Group Drill | 80% | 15% | 5% | <1% | Free early-game boost |
| Standard Borer | 75% | 20% | 5% | <1% | Steady mid-game income |
| Turbo Digger | 60% | 30% | 9% | 1% | Rapid volume farming |
| Deep Piercer | 40% | 30% | 25% | 5% | Targeting Scarce items |
| Mega Borer | 30% | 35% | 30% | 5% | Maximum Diglet yield |
| Galaxy Drill | 10% | 20% | 40% | 30% | Legendary item hunting |
As shown above, the Turbo Digger excels at pulling up high volumes of Common and Unusual items, making it incredibly consistent for raw Diglet generation. Conversely, the Deep Piercer sacrifices raw speed for a much higher chance at Scarce and Legendary drops, which are required for certain late-game quests and collections. For a deeper dive into the exact stats of each machine, check out our Drill Stats Comparison guide.
How to Upgrade Your Drill: Step-by-Step Walkthrough
The physical act of upgrading a drill in Dig a Garden is simple, but doing it efficiently without losing passive income requires a specific sequence. Follow this walkthrough to ensure you never leave your plot unproductive for long:
- Check Your Diglets: Open your HUD and confirm you have enough Diglets for the target drill, plus a small buffer (at least 10% of the upgrade cost).
- Visit the Drill Shop: Navigate to the shop area. If you are upgrading to the Group Drill, you must first visit the Roblox group page for The Heap and join. The drill will then unlock automatically in your inventory.
- Purchase the New Drill: Buy the upgraded drill. It will appear in your inventory as a placeable object.
- Prepare the Plot Slot: Walk to your plot. Do not remove your old drill yet! Place the new drill on an empty slot if you have one available. If your plot is full, carefully remove the lowest-tier drill currently running.
- Collect and Sell: Before placing the new drill, ensure you collect and sell all items from the plot. High-tier drills dig fast, and an overflowing inventory will immediately cap your earnings. If you need tips on maximizing your sales, read our Inventory Management Guide.
- Place and Activate: Place the new drill on the plot. It will automatically begin digging.
When to Upgrade — The Golden Rule & ROI Analysis
The golden rule of drill upgrades: Buy the next tier as soon as you can afford it without going completely broke.
Every minute you spend with a slower drill wastes potential earnings. The Diglets-per-hour improvement from each tier is significant, and the drill pays for itself within hours.
Upgrade Priority Ranking
- Starter Drill → Group Drill (Immediate, free) — Join The Heap group
- Starter Drill → Standard Borer (Priority 1, ~5K) — First meaningful upgrade
- Standard Borer → Turbo Digger (Priority 2, ~20K) — Major speed increase
- Turbo Digger → Deep Piercer (Priority 3, ~50K) — Better rare items
- Any A-tier → Mega Borer (Priority 4, ~100K) — Best F2P drill
Before upgrading, consider how quickly the new drill pays for itself. The table below outlines the Return on Investment (ROI) for each tier jump:
| Upgrade | Cost | Extra Diglets/Hour | Break-Even Time |
|---|---|---|---|
| Free Group Drill | 0 | +1K-2K | Instant |
| Starter → Standard | ~5K | +500-1K | 5-10 hours |
| Standard → Turbo | ~20K | +3K-5K | 4-7 hours |
| Turbo → Deep Piercer | ~50K | +5K-8K | 6-10 hours |
| Any A → Mega Borer | ~100K | +10K-20K | 5-10 hours |
Every upgrade pays for itself within 5-10 hours of gameplay. This means there is almost never a reason to delay an upgrade you can afford.
However, note that the Deep Piercer's ROI can be misleading. While its raw Diglets-per-hour might only be 5K-8K higher than the Turbo Digger, the increased frequency of Scarce and Legendary items means your actual profit can spike massively if you get lucky with high-value drops.
Offline Progression and Inventory Caps
One of the best features of Dig a Garden is offline progression. Your drills continue to dig up items even when you are not in the game. However, this mechanic comes with a critical caveat: Inventory Caps block earnings.
If your inventory fills up while you are offline, your drills will stop generating items until you log back in and sell. This makes inventory upgrades just as important as drill upgrades in the mid-to-late game.
How Offline Earnings Are Calculated
When you log off, the server calculates your total items dug per hour across all active drills. It then multiplies this by the time you were away (up to a maximum cap, usually 8-12 hours depending on game updates). If the total items dug exceed your inventory limit, the excess items are permanently lost—you gain no Diglets for them.
| Drill Combo Example | Items/Hour | Max Offline Time (Standard Inv) | Max Offline Time (Upgraded Inv) |
|---|---|---|---|
| 3x Standard Borer | ~60 | 4 Hours | 8 Hours |
| 3x Turbo Digger | ~120 | 2 Hours | 6 Hours |
| 3x Mega Borer | ~300 | <1 Hour | 4 Hours |
As demonstrated above, running three Mega Borers with a standard inventory means you will lose out on the majority of your offline progression if you are away for more than an hour. Always prioritize buying inventory expansions from the shop once you reach the Turbo Digger tier. Expanding your inventory ensures your high-tier drills actually have the space to generate wealth while you sleep or attend school.
Common Mistakes in Drill Upgrading
Mistake 1: Hoarding Diglets
Many players save up far beyond the cost of their next upgrade, thinking they need a large Diglets reserve. This is a mistake — every hour you spend with a slower drill costs you more Diglets than you would save.
Example: If you have 30K Diglets and can buy a Turbo Digger (20K), do not wait until you have 50K. The 10K remaining is enough buffer, and the Turbo Digger's increased earnings will replace the spent Diglets quickly.
Mistake 2: Skipping Tiers
Some players try to save directly for a Mega Borer from a Standard Borer. This wastes hours of potential earnings from the Turbo Digger and Deep Piercer tiers.
Rule: Buy each tier in sequence. Each tier upgrade is worth the investment.
Mistake 3: Not Filling Plot Slots
Upgrading one drill while leaving plot slots empty is inefficient. A Standard Borer on an empty slot earns more total Diglets than upgrading one existing drill from A-tier to S-tier.
Rule: Fill all empty slots before focusing on individual drill upgrades.
Mistake 4: Ignoring Inventory Upgrades
As covered in the offline progression section, having the best drills in the game means nothing if your inventory fills up in thirty minutes. Players often dump 100K Diglets into a Mega Borer while completely neglecting the inventory shop. If you plan to be offline for 8 hours, a Turbo Digger with an expanded inventory will easily out-earn a Mega Borer with a base inventory. Balance your upgrades between digging power and storage capacity.
FAQ
Q: Should I sell my old drill to help afford a new one? A: Removing a drill gives a partial refund, but it is not full value. Only remove a drill if you are immediately placing a better one in the same slot. Never leave a slot empty.
Q: How many drills should I have before upgrading individual ones? A: Fill all available plot slots first, then upgrade drills one at a time starting with the lowest tier.
Q: Is the Galaxy Drill worth waiting for? A: The Galaxy Gamepass is currently off-sale. If it returns, it is the best drill for legendary hunting but not necessarily better than Mega Borer for Diglets/hour. F2P players should focus on Mega Borers.
Q: Can I have multiple Mega Borers? A: Yes, and you should! The optimal F2P end-game is a full plot of Mega Borers for maximum Diglets per hour.
Q: How do offline earnings work if I have different drill tiers on my plot? A: The game calculates the aggregate output of all your drills. If you have one Mega Borer and one Starter Drill, the server adds their items-per-hour together. However, because the Mega Borer produces high-value items rapidly, it will consume the bulk of your inventory space, making the Starter Drill's contribution effectively useless. Always aim for uniform, high-tier drills on your plot.
Q: Should I upgrade my inventory or my drill first? A: If your current drill fills your inventory in under 4 hours, buy an inventory upgrade first. This ensures you maximize overnight offline earnings. If your inventory takes more than 6 hours to fill, save for the drill upgrade instead.
Q: Does the placement of a drill on my plot affect its digging speed or item rarity? A: No. Drill placement is purely cosmetic and organizational. A drill placed in the corner of your plot performs identically to one placed in the center. Focus on filling slots rather than optimizing physical layout.